- - - - - - DEVICES - - - - - -..........................................................................43
LAPTOPS...............................................................................................43
Battery............................................................................................... 43
Keyboard........................................................................................... 44
Memory..............................................................................................44
SO-DIMM...................................................................................... 44
Integrated......................................................................................44
Storage.............................................................................................. 44
Hard Drive.....................................................................................44
SSD...............................................................................................44
Drive Replacement....................................................................... 45
Data Migration...............................................................................45
Wireless and Bluetooth......................................................................45
Biometrics..........................................................................................46
NFC................................................................................................... 46
Displays............................................................................................. 46
LCD...............................................................................................46
TN.............................................................................................47
IPS............................................................................................47
VA.............................................................................................47
OLED (organic LED)..................................................................... 47
Microwave Antenna...................................................................... 47
Webcam........................................................................................48
Backlights.......................................................................................... 48
CCFL.............................................................................................48
LED............................................................................................... 48
Replacement.................................................................................48
Digitizer..............................................................................................49
Stylus only.....................................................................................49
Touch-screen................................................................................ 49
MOBILE DEVICES.................................................................................49
Connectivity....................................................................................... 49
Wired.............................................................................................49
USB.......................................................................................... 49
DB-9 serial (pre-USB).............................................................. 50
Wireless........................................................................................ 50
NFC.......................................................................................... 50
BT.............................................................................................50
Wifi Hotspot.............................................................................. 50
Input / Output.....................................................................................50
Touch pen / Touchscreen stylus / Capacitive stylus......................51
Active stylus (digital stylus)........................................................... 51
External drawing pad.................................................................... 51
Trackpad....................................................................................... 51
External trackpad.......................................................................... 51
2-way Headsets............................................................................ 51
Speakers.......................................................................................52
Docking station............................................................................. 52
Port replicator................................................................................52
Cellular Networks.............................................................................. 52
2G (original).................................................................................. 52
3G (1998)......................................................................................53
4G / LTE........................................................................................53
5G (2020)......................................................................................53
PRL............................................................................................... 53
Wifi Hotspot...................................................................................54
Bluetooth........................................................................................... 54
GPS................................................................................................... 54
MDM.................................................................................................. 55
Mobile Device Configuration..............................................................55
- - - - - NETWORKING - - - - -..................................................................... 56
NETWORK PROTOCOLS..................................................................... 56
IP....................................................................................................... 56
Transport Layer................................................................................. 57
TCP................................................................................................... 58
UDP................................................................................................... 58
Connectionless protocols.................................................................. 59
DHCP............................................................................................59
TFTP............................................................................................. 59
Connection-oriented protocols...........................................................59
HTTPS.......................................................................................... 59
SSH...............................................................................................60
IP Addresses, Ports, Sockets............................................................ 60
IP...................................................................................................60
Port number.................................................................................. 60
IPv4 Sockets................................................................................. 60
Non-ephemeral ports................................................................61
Ephemeral ports....................................................................... 61
32-bitCommon Port Numbers............................................................62
tcp/20............................................................................................ 62
tcp/21............................................................................................ 62
tcp/22............................................................................................ 62
tcp/23............................................................................................ 63
tcp/25............................................................................................ 63
udp/53........................................................................................... 63
udp/67........................................................................................... 63
udp/68........................................................................................... 63
tcp/80............................................................................................ 64
tcp/443.......................................................................................... 64
tcp/110.......................................................................................... 64
tcp/143.......................................................................................... 64
udp/137......................................................................................... 65
tcp/139.......................................................................................... 65
tcp/445.......................................................................................... 65
udp/161......................................................................................... 65
udp/162......................................................................................... 66
tcp/389.......................................................................................... 66
tcp/3389........................................................................................ 66
NETWORK DEVICES............................................................................ 67
Router (Layer 3 Device).................................................................... 67
Switch (Layer 2 device?)................................................................... 67
Multilayer Switch...................................................................... 68
Unmanaged Switch (Fixed Configuration).................................... 68
Managed Switch (Multi-functioning)..............................................68
Access point...................................................................................... 69
Cable infra......................................................................................... 69
Physical cables............................................................................. 69
Patch Panel...................................................................................69
RJ45..............................................................................................70
Firewall (Layer 4 device)................................................................... 70
Power over Ethernet (PoE)................................................................70
Endspan........................................................................................71
Midspan........................................................................................ 71
Different types of power - IEEE 802.3 Standards......................... 71
af.............................................................................................. 71
at.............................................................................................. 71
bt.............................................................................................. 71
Hub.................................................................................................... 72
Cable Modem................................................................................72
DOCSIS....................................................................................72
ADSL.............................................................................................73
Optical network terminal............................................................... 73
NIC................................................................................................73
Software Defined Networking............................................................ 74
Infrastructure Layer.......................................................................74
Forwarding............................................................................... 75
Trunking................................................................................... 75
Encrypting................................................................................ 75
Ntwk Address Translation (NAT).............................................. 75
Control Layer................................................................................ 75
Dynamic Routing protocols...................................................... 75
Forwarding tables (switch)....................................................... 75
Routing tables, NAT table,Session tables (router)................... 75
Application Layer.......................................................................... 75
aka ‘Management plane’.......................................................... 75
SDN Description of Physical Device............................................. 76
Modularity of Layers.......................................................................... 76
Create new devices from combined functionality..................... 76
WIRELESS STANDARDS......................................................................76
802.11a (original)............................................................................... 77
802.11b (original)............................................................................... 77
802.11g (upgrade to ‘b’).....................................................................78
802.11n (Wi-Fi 4)............................................................................... 78
MIMO............................................................................................ 78
802.11ac (Wi-Fi 5)............................................................................. 78
802.11ax (current, Wi-Fi 6)................................................................ 79
OFDMA......................................................................................... 80
Antennae / Long-range fixed wireless solutions................................ 80
Stock WAP antenna...................................................................... 80
Fixed antenna............................................................................... 80
Directional antenna....................................................................... 80
RFID.................................................................................................. 81
NFC................................................................................................... 82
Physical retail payment systems...................................................82
Bootstrap for other Wireless / Bluetooth....................................... 82
Access token – identity “card”.......................................................82
WIRELESS BROADCAST SPECIFICATIONS.......................................82
802.11 Technical Specifications.........................................................83
Band Selection and Bandwidth..........................................................83
2.4G Spectrum for N. America......................................................83
5 G Spectrum................................................................................83
Bluetooth........................................................................................... 84
NETWORK SERVICES IN THE DATA CENTER................................... 85
DNS Server....................................................................................... 85
DHCP Server.....................................................................................85
File Server......................................................................................... 86
SMB – Server Message Block...................................................... 86
AFP – Apple Filing Protocol......................................................... 86
Print Server........................................................................................86
SMB.............................................................................................. 87
IPP................................................................................................ 87
LPD............................................................................................... 87
Mail Server........................................................................................ 87
Syslog................................................................................................87
SIEM.........................................................................................88
Web Server................................................................................... 88
Authentication Server....................................................................88
Always available.......................................................................89
Redundancy............................................................................. 89
Spam................................................................................................. 89
Mail / Spam Gateway....................................................................89
All-In-One Security appliance............................................................ 90
Next generation firewall................................................................ 90
UTM.............................................................................................. 90
Load Balancers..................................................................................90
Web Server Farms........................................................................91
Database Farms........................................................................... 91
TCP offload................................................................................... 91
SSL offload................................................................................... 91
Caching.........................................................................................91
Prioritization.................................................................................. 91
Content switching..........................................................................92
Proxy Server......................................................................................92
SCADA / ICS..................................................................................... 92
Issues with Legacy and Embedded Systems.................................... 93
Legacy.......................................................................................... 93
Embedded.....................................................................................93
IoT Devices................................................................................... 93
INTERNET PROTOCOL & ADDRESSING............................................ 94
IPv4 Addresses................................................................................. 94
IPv6 Addresses................................................................................. 95
DNS Usage................................................................................... 96
Subnet Mask................................................................................. 96
Manual Configuration........................................................................ 96
Assignment of IP Addresses............................................................. 97
BOOTP......................................................................................... 98
DHCP............................................................................................98
DORA - Discover - Offer - Request - Acknowledge................. 98
IP Address Pool......................................................................100
Dynamic................................................................................. 100
Static...................................................................................... 100
IP Reservation........................................................................100
APIPA..........................................................................................100
Functional blocks....................................................................101
ARP........................................................................................ 101
DNS Configuration...........................................................................101
gTLD.......................................................................................102
ccTLD..................................................................................... 102
DNS Lookup................................................................................103
dig...........................................................................................103
nslookup................................................................................. 104
Resource Records...................................................................... 104
DNS Configuration File...........................................................105
DNS Service Front End (Web-based).................................... 105
Address Record (A) / (AAAA)..................................................... 105
TTL......................................................................................... 106
Mail Exchanger Record (MX)......................................................107
Text Records (TXT).....................................................................107
Verification purposes.............................................................. 107
Email security......................................................................... 107
Sender Policy Framework (SPF)................................................ 108
Domain Keys Identified Mail (DKIM)........................................... 109
DMARC.................................................................................. 110
Compliance Report................................................................. 111
DHCP Configuration.........................................................................111
DHCP Pools................................................................................ 112
DHCP address allocation systems..............................................114
Dynamic..................................................................................114
Automatic................................................................................114
Reservation (Admin)...............................................................114
Media Access Control (MAC)................................................. 114
Static DHCP........................................................................... 114
Leasing........................................................................................114
Reallocation processes.......................................................... 115
DHCP renewal............................................................................ 115
T1 timer.................................................................................. 115
T2 timer.................................................................................. 116
Redundant DHCP Server....................................................... 116
VLAN & VPN........................................................................................ 117
Local Area Networks (LAN).........................................................117
Virtual Local Area Networks (VLAN)................................................117
Virtual Private Networks (VPN)........................................................118
Concentrator............................................................................... 118
Standalone............................................................................. 118
Integration...............................................................................118
Encrypted Tunnel....................................................................119
INTERNET CONNECTIONS................................................................ 119
Satellite Networking.........................................................................120
Fiber................................................................................................ 120
Cable Broadband.............................................................................121
DOCSIS..................................................................................121
DSL..................................................................................................121
Asymmetric Digital Subscriber Line (ADSL)............................... 121
Cellular Networks............................................................................ 122
Tethering..................................................................................... 122
Hotspot........................................................................................122
Wireless Internet Service Provider (WISP)................................. 122
Outdoor Antennas.................................................................. 122
Mesh Networks.......................................................................123
NETWORK TYPES.............................................................................. 123
Local Area Network (LAN)...............................................................123
Ethernet...................................................................................... 123
802.11 Wireless.......................................................................... 123
Wide Area Network (WAN).............................................................. 123
Personal Area Network (PAN)......................................................... 124
Bluetooth.....................................................................................124
Infrared (IR).................................................................................124
NFC.............................................................................................124
Metropolitan Area Network (MAN)...................................................124
Metro Ethernet............................................................................ 124
Storage Area Network (SAN).......................................................... 125
Block-level Access................................................................. 125
Wireless LAN (WLAN)..................................................................... 125
NETWORK TOOLS..............................................................................125
Cable Crimpers................................................................................125
Twisted Pair Crimpers.................................................................126
Best Practices............................................................................. 126
Wi-Fi Analyzer................................................................................. 126
Tone Generator................................................................................126
Generator............................................................................... 127
Inductive probe.......................................................................127
Modular Jack.......................................................................... 127
Alligator clips.......................................................................... 127
Punch down connectors......................................................... 127
Punch Down Tool.............................................................................127
Wiring Blocks.............................................................................. 127
Best Practices............................................................................. 128
Cable Tester.................................................................................... 128
Missed Cables........................................................................128
Punched Down Incorrectly..................................................... 128
Cross-Wires............................................................................128
Time Domain Reflectometer...................................................129
Loopback Plugs............................................................................... 129
Serial / RS-232....................................................................... 129
Ethernet..................................................................................129
T1 WAN.................................................................................. 129
Fiber....................................................................................... 129
Taps and Port Mirrors...................................................................... 129
Physical Taps.............................................................................. 129
Passive...................................................................................130
Active......................................................................................130
Example Routing Schematic in a Tap.....................................131
Port Mirror................................................................................... 131
SPAN......................................................................................131
NETWORK CABLES............................................................................132
Twisted Pair Copper Cabling........................................................... 132
Balanced Pair operation..............................................................132
Twist............................................................................................132
Different levels of Twist Rate..................................................132
Ethernet Standard.................................................................. 133
Maximum Distance.................................................................133
Category 5.................................................................................. 133
Category 5e (enhanced)............................................................. 133
Category 6.................................................................................. 133
Category 6A (augmented)...........................................................133
Coaxial Copper Cabling...................................................................133
RG-6.......................................................................................134
Plenum-Rated Cable....................................................................... 134
PVC jacket..............................................................................134
FEP / Low-smoke PVC...........................................................134
Shielded Cable................................................................................ 135
UTP.............................................................................................135
STP............................................................................................. 135
Nomenclature..............................................................................135
U.............................................................................................135
S............................................................................................. 135
F............................................................................................. 135
Direct Burial STP............................................................................. 136
Waterproof jacket................................................................... 136
Repellent gel filling................................................................. 136
Shielded Twisted Pair.............................................................136
Optical Fiber.................................................................................... 137
Light Source........................................................................... 138
Light........................................................................................138
Core........................................................................................138
Cladding................................................................................. 138
Buffer......................................................................................138
Ferrule.................................................................................... 138
Multimode Fiber.......................................................................... 139
Single-mode Fiber.......................................................................140
Cabling Standard Structures........................................................... 140
ISO/IEC 11801............................................................................ 140
Telecoms Industry Association - TIA...........................................140
ANSI/TIA-568......................................................................... 140
The Color Standards...................................................................141
T568A.....................................................................................141
T568B.....................................................................................141
Horizontal Cabling.................................................................. 141
Organizational End Users...................................................... 141
- - - - - - HARDWARE - - - - - -.................................................................. 142
PERIPHERAL CABLES....................................................................... 142
Universal Serial Bus – USB.............................................................142
USB 1.1.......................................................................................142
USB 2.0.......................................................................................143
USB 3.0.......................................................................................143
Connectors for Early USB...........................................................143
A plug..................................................................................... 143
B plug..................................................................................... 143
Mini-B..................................................................................... 143
Micro-B................................................................................... 143
Higher Speed Connectors...........................................................143
3.0 A plug............................................................................... 143
3.0 B plug............................................................................... 143
3.0 Micro-B............................................................................. 143
USB-C Connectors..................................................................... 144
3.1.......................................................................................... 144
3.2.......................................................................................... 145
Thunderbolt..................................................................................... 145
V1........................................................................................... 145
V2........................................................................................... 146
V3........................................................................................... 146
Serial Console cables......................................................................146
DB-9....................................................................................... 146
DB-25..................................................................................... 146
RS-232........................................................................................146
VIDEO CABLES...................................................................................146
VGA................................................................................................. 146
DisplayPort...................................................................................... 147
MiniDisplayPort...................................................................... 147
DisplayPort............................................................................. 147
DVI...................................................................................................148
Single Link..............................................................................148
Dual Link................................................................................ 148
DVI-A......................................................................................148
DVI-D......................................................................................148
DVI-I....................................................................................... 148
SATA.................................................................................................... 149
eSATA..............................................................................................150
SCSI.....................................................................................................150
PATA.......................................................................................151
IDE.....................................................................................151
SATA...................................................................................... 151
Narrow Bus.............................................................................151
Wide Bus................................................................................ 151
SCSI ID....................................................................................... 152
Logical Unit - LUN.......................................................................153
SCSI Terminator..................................................................... 153
Serial Attached SCSI - SAS........................................................153
PATA / IDE............................................................................................153
40 Wire................................................................................... 154
80 Wire................................................................................... 154
ADAPTERS & CONVERTERS.............................................................154
COPPER CONNECTORS....................................................................156
RJ11 Connector............................................................................... 156
RJ45 Connector...............................................................................156
F-connector..................................................................................... 157
Punchdown Block............................................................................ 157
USB 1.1 / 2.0 Connectors................................................................158
USB 3.0 connectors.........................................................................158
USB-C............................................................................................. 159
Molex connector.............................................................................. 159
Lightning connector......................................................................... 159
DB-9................................................................................................ 160
FIBER CONNECTORS........................................................................ 160
LC - Local Connector.......................................................................160
ST - Straight Tip...............................................................................160
SC - Subscriber Connector aka ‘Square’.........................................161
MEMORY............................................................................................. 161
Random Access Memory (RAM)..................................................... 161
Slots............................................................................................ 161
DIMM......................................................................................161
SO-DIMM............................................................................... 161
DRAM......................................................................................... 161
Dynamic................................................................................. 162
Random..................................................................................162
SDRAM....................................................................................... 162
Synchronous.......................................................................... 162
DDR............................................................................................ 162
DDR3......................................................................................162
DDR4......................................................................................162
DDR5......................................................................................163
MEMORY TECHNOLOGIES................................................................163
Virtual Memory................................................................................ 163
Multi-Channel Memory.................................................................... 163
Color-coded Slots...................................................................164
Error Checking.................................................................................164
Parity Memory........................................................................ 164
Error Correcting Code (ECC)................................................. 164
Parity...........................................................................................164
‘Even’ Parity........................................................................... 164
STORAGE DEVICES........................................................................... 165
Hard Disk Drives - HDD...................................................................165
Non-Volatile............................................................................ 165
Random-access..................................................................... 165
Moving parts...........................................................................165
Sizes........................................................................................... 166
Solid-State Drivers - SSD................................................................ 166
Non-volatile............................................................................ 166
Durability................................................................................ 167
Performance...........................................................................167
Interface...................................................................................... 167
Portability................................................................................167
mSATA................................................................................... 167
m.2......................................................................................... 167
Controllers...................................................................................168
AHCI (SATA).......................................................................... 168
NVMe (M.2)............................................................................ 168
Installation...................................................................................168
Flash Drives.....................................................................................169
Electrically Erasable Programmable Read-Only Memory...... 169
Non-volatile............................................................................ 169
Write Limits.............................................................................169
Unlimited Reads..................................................................... 169
Example Formats........................................................................169
USB Flash Drive.....................................................................170
Secure Digital - SD.................................................................170
MiniSD....................................................................................170
MicroSD..................................................................................170
CompactFlash - CF................................................................ 170
xD Picture Card...................................................................... 171
Optical Drive.................................................................................... 171
Formats.......................................................................................172
CD-ROM.................................................................................172
DVD-ROM.............................................................................. 172
Blu-Ray...................................................................................172
RAID.....................................................................................................172
Redundant Array of Independent Disks...........................................172
RAID Levels.....................................................................................172
Raid 0 (Striping).......................................................................... 173
RAID 1 (Mirroring).......................................................................173
RAID 5 (Striping w/ Parity).......................................................... 174
RAID 10 (Stripe of Mirrors)......................................................... 175
MOTHERBOARDS.............................................................................. 176
CPU........................................................................................176
Memory Slots......................................................................... 176
Power Connectivity.................................................................176
Expansion Slots......................................................................176
Desktop.................................................................................. 177
Form Factor Devices.............................................................. 177
Choosing the Right Form Factor..................................................... 177
ATX vs. ITX Families...................................................................177
Standard-ATX.........................................................................177
Mini-ITX.................................................................................. 177
Expansion Slots...............................................................................178
Computer Buses.....................................................................178
Conventional PCI........................................................................ 178
32-bit...................................................................................... 178
64-bit...................................................................................... 178
Parallel Communication......................................................... 178
I/O Controller Hub.................................................................. 178
3.3V key................................................................................. 180
5V key.................................................................................... 180
PCI Express................................................................................ 181
Serial Lanes........................................................................... 182
X1........................................................................................... 183
x2............................................................................................183
X4........................................................................................... 183
X8........................................................................................... 183
X16......................................................................................... 183
x32..........................................................................................183
24-Pin Motherboard Power......................................................... 183
4-Pin ATX Power.........................................................................184
ATX12V / P4 / CPU................................................................ 184
Storage Drive Interfaces............................................................. 184
SATA connectors.................................................................... 184
eSATA connector....................................................................184
Headers...................................................................................... 185
AAFP...................................................................................... 185
Other Audio functions.............................................................185
USB........................................................................................ 185
USB 3.0.................................................................................. 185
TPM........................................................................................185
FAN........................................................................................ 186
RESET Switch........................................................................186
Hard Drive Light..................................................................... 186
Power Light............................................................................ 186
M.2 Connector............................................................................ 186
Motherboard Compatibility...............................................................186
CPU Socket............................................................................186
Server Mobos..............................................................................186
Larger ATX............................................................................. 187
Rack-mount System............................................................... 187
Desktop Mobos........................................................................... 187
Mobile Mobos..............................................................................187
BIOS.....................................................................................................189
Power On............................................................................... 189
POST......................................................................................189
Boot Loader............................................................................190
Legacy BIOS...............................................................................190
UEFI BIOS.................................................................................. 191
BIOS Settings.................................................................................. 192
Accessing....................................................................................192
Secret Buttons........................................................................192
Hyper-V (Windows)................................................................ 192
VMWare Workstation Player.................................................. 192
Virtual BIOS Simulators (online).............................................192
Fast Startup (Windows 8/10/11)..................................................192
Secret Hard Button Press.......................................................193
Forced Restart........................................................................193
System Configuration............................................................. 193
Boot Load Interruption............................................................193
Backups...................................................................................... 193
Downloadable Copy............................................................... 194
Written Notes..........................................................................194
Snap a Pic.............................................................................. 194
Modifications............................................................................... 194
Boot Options............................................................................... 194
Enable/Disable HW Devices.................................................. 194
Boot Order..............................................................................194
USB Interface / Permissions....................................................... 195
USB Setup..............................................................................195
Fans............................................................................................ 195
Integrated Fan Controller....................................................... 196
Configuration.......................................................................... 196
Secure Boot................................................................................ 196
Malicious Software................................................................. 196
Digital Signatures................................................................... 196
UEFI Secure Boot....................................................................... 197
OS Public Key........................................................................ 197
Bootloader Trusted Certificate................................................197
Boot PW Management................................................................197
BIOS / User PW..................................................................... 197
Supervisor PW....................................................................... 197
‘CMOS’ / BIOS config.............................................................197
Flash Memory.........................................................................197
Jumper Reset......................................................................... 198
CMOS Battery Reset..............................................................198
Trusted Platform Module (TPM)..................................................198
Cryptographic Processor........................................................198
Persistent Memory................................................................. 198
Versatile Memory....................................................................198
PW Protected......................................................................... 199
Hardware Security Module (HSM).............................................. 199
Standalone, Purpose-Built Appliance.....................................199
Plug-In Adapter Card..............................................................199
Cryptographic Accelerator......................................................199
CPU......................................................................................................199
Architectures....................................................................................200
32-bit........................................................................................... 200
64-bit........................................................................................... 200
ARM............................................................................................ 200
Software / Driver Compatibility....................................................200
Processor Cores..............................................................................201
Dual Core............................................................................... 201
Quad Core..............................................................................201
Multi-Core...............................................................................201
Caches........................................................................................201
Dedicated Caches.................................................................. 202
Shared Caches.......................................................................202
Multithreading............................................................................. 202
Hyper-Threading Technology (HTT).......................................202
Virtualization Support...................................................................... 203
Intel Virtualization Technology (VT)........................................203
AMD Virtualization (AMD-V)...................................................203
EXPANSION CARDS........................................................................... 203
Sound Card..................................................................................... 203
Output......................................................................................... 203
Multiple inputs............................................................................. 204
Interfaces.................................................................................... 204
3.5mm Headphone stereo......................................................204
RCA L/R................................................................................. 204
Line In stereo..........................................................................204
SPDIF.....................................................................................204
Video Card.......................................................................................204
Discrete Graphics Card.......................................................... 204
Interfaces.................................................................................... 205
VGA........................................................................................205
DVI......................................................................................... 205
DisplayPort............................................................................. 205
HDMI...................................................................................... 205
Capture Card................................................................................... 205
Interfaces.................................................................................... 205
HDMI...................................................................................... 205
SDI......................................................................................... 206
Network Interface Card (NIC).......................................................... 206
Multi-port Ethernet...................................................................... 206
Documentation................................................................................ 206
Minimum Reqs....................................................................... 206
Knowledge Base.................................................................... 206
Support Forums......................................................................206
Driver Installation........................................................................ 207
Plug-n-Play.............................................................................207
COOLING.............................................................................................207
Case Fans....................................................................................... 207
Critical factors............................................................................. 207
Mobo Layout...........................................................................208
Component Location.............................................................. 208
Devices...................................................................................208
Wiring..................................................................................... 208
Power..................................................................................... 208
Fan Size & Style.....................................................................208
On-Board Fans................................................................................ 208
Fan Specifications........................................................................... 208
Standard Sizes............................................................................208
Different Speeds......................................................................... 208
Noise Levels............................................................................... 208
Passive / Fanless............................................................................ 209
Common Applications:................................................................ 209
Video Servers.........................................................................209
TV head unit........................................................................... 209
Satellite receiver.....................................................................209
Media Server.......................................................................... 209
Heat Sink......................................................................................... 209
Thermal Paste........................................................................ 209
Thermal Pad...........................................................................209
Liquid Cooling..................................................................................210
Liquid Heat Exchanger / CPU Block.......................................210
Coolant Radiator & Fan..........................................................210
POWER SUPPLY................................................................................. 211
3.3 V DC................................................................................. 211
5 V DC.................................................................................... 211
12 V DC.................................................................................. 211
Amperage (A)..............................................................................211
Voltage (V).................................................................................. 211
Wattage (W)................................................................................ 211
Volts * Amps = Watts..............................................................212
Current.............................................................................................212
Alternating Current - AC..............................................................212
Long Distance........................................................................ 212
Frequency.............................................................................. 212
Direct Current - DC.................................................................... 212
Dual-Voltage Inputs......................................................................... 212
Auto-Switching Power Supply................................................ 213
Power Supply Outlets...................................................................... 213
Positive vs. Negative...................................................................213
+12 V.......................................................................................... 213
PCIe adapters........................................................................ 214
Hard drive motors...................................................................214
Cooling Fans.......................................................................... 214
Other modern components.....................................................214
+5V............................................................................................. 214
Legacy MOBO components................................................... 214
+3.3V.......................................................................................... 214
M.2 slots................................................................................. 214
RAM slots............................................................................... 214
MoBO Logic Circuits...............................................................214
+5 VSB (Stand-By)..................................................................... 214
-12V............................................................................................ 214
Integrated LAN....................................................................... 214
Serial Ports (older)................................................................. 214
PCI cards (some)................................................................... 214
-5V.............................................................................................. 214
ISA adapter cards...................................................................215
24-Pin Mobo Power Connector....................................................... 215
Redundancy.................................................................................... 217
Hot-Swappable.......................................................................217
Connectors...................................................................................... 218
Fixed Connectors........................................................................218
Modular....................................................................................... 218
Size..................................................................................................219
Sizing a PSU...............................................................................220
Video Cards............................................................................220
50% Rule-of-Thumb............................................................... 220
- - - - - - PRINTERS - - - - - -.................................................................... 220
MULTIFUNCTION DEVICE (MFD).......................................................220
Printer.....................................................................................221
Scanner.................................................................................. 221
Fax......................................................................................... 221
Network connection................................................................221
Phone line connection............................................................ 221
Print from Web....................................................................... 221
Spatial & Location requirements......................................................221
Power..................................................................................... 221
Network.................................................................................. 221
Accessibility............................................................................221
Printer Drivers..................................................................................221
OS version..............................................................................221
Architecture version................................................................221
Printer Command Language (PCL)............................................ 222
PostScript....................................................................................222
Wired Device Sharing......................................................................222
USB Type B............................................................................222
Ethernet..................................................................................222
Bluetooth................................................................................ 222
802.11 Infrastructure mode.................................................... 223
802.11 Ad hoc mode.............................................................. 223
Sharing the Printer...........................................................................223
Create a Printer Share (e.g. in Windows)................................... 223
Create a Print Server.................................................................. 223
Configuration Settings..................................................................... 224
Duplex.........................................................................................224
Orientation.................................................................................. 224
Portrait....................................................................................224
Landscape..............................................................................224
Tray Settings............................................................................... 224
Quality.........................................................................................224
Resolution.............................................................................. 225
No Color - Greyscale..............................................................225
Color-Saving...........................................................................225
Printer Security................................................................................ 225
User Authentication.....................................................................225
Badging.......................................................................................225
Audit Logs................................................................................... 225
Cost management.................................................................. 226
Security monitoring.................................................................226
Secured Prints............................................................................ 226
Flatbed Scanner.............................................................................. 226
All-in-1 Multifunction Device................................................... 226
Standalone Flatbed................................................................ 226
Automated Document Feeder - ADF......................................226
Network Scan Services................................................................... 226
Scan to Email..............................................................................226
Scan to Folder.............................................................................227
Server Message Block - SMB................................................ 227
Microsoft Share...................................................................... 227
Scan to Cloud............................................................................. 227
LASER PRINTERS.............................................................................. 227
Imaging Drum.................................................................................. 227
Photosensitive drum...............................................................228
Replacement...............................................................................228
Separate component.............................................................. 228
Combined w/ Toner Cartridge.................................................228
Fuser Assembly...............................................................................228
Transfer Belt and Roller...................................................................229
Pickup Rollers..................................................................................229
Possible Malfunctions:............................................................230
Separation Pad................................................................................231
Duplexing Assembly........................................................................ 232
Included mechanism.............................................................. 232
Add-on....................................................................................232
Printing Process.............................................................................. 233
1. Processing..........................................................................233
2. Charging.............................................................................234
3. Exposing.............................................................................235
5. Transferring........................................................................ 237
6. Fusing.................................................................................237
7. Cleaning............................................................................. 237
LASER PRINTER MAINTENANCE..................................................... 238
Organic PhotoConductor drum...............................................239
Variations.................................................................................... 239
Maintenance Kit for Laser Printers.................................................. 239
Global Page Counter..............................................................240
Laser Printer Calibration..................................................................240
Cleaning.......................................................................................... 240
Best Practices............................................................................. 240
LaserPrinter vacuum.............................................................. 241
INKJET PRINTERS..............................................................................241
Ink Cartridges.................................................................................. 241
Integrated Print Heads........................................................... 242
Feed Rollers.................................................................................... 242
Duplexing.................................................................................... 242
Carriage and Belt.............................................................................242
Printer Calibration............................................................................243
INKJET PRINTER MAINTENANCE.....................................................244
Malfunction Signs........................................................................244
Manual Remedy..........................................................................244
Replacing Inkjet Cartridges............................................................. 244
Inkjet Printer Calibration.................................................................. 244
Clearing Paper Jams....................................................................... 245
THERMAL PRINTERS.........................................................................245
Use Cases....................................................................................... 245
Feed Assembly................................................................................246
Heating Element.............................................................................. 246
Thermal Paper.................................................................................246
Thermochromic Paper / Thermal paper................................. 246
THERMAL PRINTER MAINTENANCE................................................ 246
Replacing Paper.............................................................................. 246
Cleaning Heating Element...............................................................247
Cleaning Cards.......................................................................247
Removing Debris............................................................................. 247
Avoiding Hot Areas.......................................................................... 248
IMPACT PRINTERS.............................................................................248
Dot-Matrix Printer................................................................... 248
Heat Sink................................................................................249
Printer Ribbon..................................................................................250
Proprietary Sizes.........................................................................250
Tractor Feed.................................................................................... 251
Perforated Edged Paper.........................................................251
Greenbar paper...................................................................... 251
Feeding Process......................................................................... 251
3D PRINTERS..................................................................................... 251
Additive Manufacturing...........................................................251
Filament printing......................................................................... 252
Fused Deposition Modeling (FDM).........................................252
Resin Printing..............................................................................254
Stereolithography (SLA)......................................................... 254
Print Bed..........................................................................................255
Clean...................................................................................... 255
Level.......................................................................................255
Stable..................................................................................... 255
- - - CLOUD / VIRTUAL - - -..................................................................... 256
CLOUD MODELS................................................................................ 256
Cloud Computing.............................................................................256
Performance...........................................................................256
Distributed.............................................................................. 256
Service-based........................................................................ 256
Deployment Models.........................................................................256
Private.........................................................................................256
Public.......................................................................................... 256
Hybrid..........................................................................................257
Community..................................................................................257
Comparison of Cloud Models.......................................................... 257
Cloud Characteristics...................................................................... 257
Shared Resources...................................................................... 258
Internal Cloud......................................................................... 258
External Cloud........................................................................258
Metered Cloud services..........................................................258
Non-Metered.......................................................................... 258
Rapid Elasticity........................................................................... 258
Instant Resource Provisioning................................................258
High Avalability.......................................................................258
File Synchronization............................................................... 259
Infrastructure as a Service (IaaS)....................................................259
Software-as-a-Service (SaaS).........................................................259
Platform-as-a-Service (PaaS)..........................................................260
Deskstop-As-a-Service - DaaS........................................................260
Virtual Desktop Infrastructure (VDI)....................................... 260
High Network Connectivity (dependency).............................. 260
CLIENT-SIDE VIRTUALIZATION......................................................... 261
Host-based virtualization........................................................ 261
Standalone server.................................................................. 261
Legacy Software on Newer OS....................................................... 261
OS-Specific Application/Release............................................261
Cross-Platform Virtualization........................................................... 261
Hypervisor...................................................................................262
Virtual Machine Manager....................................................... 262
Hardware Virtualization (built-in)............................................ 262
Hardware Mgmt......................................................................262
Processor Support...................................................................... 262
Intel Virtualization Technology (VT)........................................262
AMD-V....................................................................................262
Memory....................................................................................... 262
Disk Space..................................................................................262
Network.......................................................................................262
Standalone............................................................................. 263
NAT........................................................................................ 263
Bridged................................................................................... 263
Virtual Switch.............................................................................. 263
Sandboxing......................................................................................263
Rollback features....................................................................263
Building the App..........................................................................263
Develop Environment............................................................. 263
Test Environment....................................................................263
Hypervisor Security......................................................................... 264
VM escaping...........................................................................264
Guest OS Security...........................................................................264
Host based Firewall................................................................264
ANti-Virus Spyware................................................................ 264
Rogue VMs.............................................................................264
Network Requirements.................................................................... 264
Shared Network Address............................................................ 265
Network Address Translation (NAT)....................................... 265
Bridged Network Address........................................................... 265
Private Address...........................................................................265
Network of VMs (Internal only)............................................... 265
- - - TROUBLESHOOTING - - -................................................................ 265
TROUBLESHOOTING PROCESS...................................................... 265
Change Control...................................................................... 265
Identify the Problem.........................................................................267
Information gathering.................................................................. 267
Identify symptoms....................................................................... 267
Question the users......................................................................267
Compare Records.......................................................................268
Approach multiple problems separately......................................268
Backup Everything...................................................................... 268
Rollback Plan......................................................................... 268
What else has Changed?............................................................268
Sources of Clues.........................................................................268
Establish a Theory...........................................................................268
Start with Obvious Causes first...................................................269
Consider Everything....................................................................269
List All Possible Causes..............................................................269
Root Cause Analysis.............................................................. 269
Research the symptoms............................................................. 269
Test the Theory................................................................................269
Confirm each Theory.................................................................. 269
Theories didnt Work?..................................................................270
Escalate..................................................................................270
Create a Plan of Action....................................................................270
Build the Plan..............................................................................270
Refer to vendor instructions........................................................ 270
Identify Potential Effects............................................................. 270
Implement the Solution....................................................................270
Fix the Issue................................................................................270
Change Control Window........................................................ 271
Verify Full System Functionality.......................................................271
Acceptance Criteria................................................................ 271
Implement preventative measures..............................................271
Document Findings..........................................................................271
Documentation....................................................................... 271
Helpdesk / Knowledgebase Software.....................................272
TROUBLESHOOTING COMMON HARDWARE PROBLEMS............ 272
Power On Self Test - POST.............................................................272
Consult Motherboard Documentation.....................................272
Blank Screen...............................................................................272
BIOS time and date setting......................................................... 273
Prompt: Incorrect or Reset time & date.................................. 273
Solution: Replace the Battery.................................................273
Attempt to Boot from incorrect Device........................................ 273
Start BIOS config and fix Boot order...................................... 273
Confirm startup device has valid OS...................................... 273
USB drive may also be superceding other drives.................. 273
Windows Stop Error – Bluescreen of Death (BSOD)...................... 273
Stop Code.............................................................................. 274
Windows Event Viewer...........................................................274
Third Party Support................................................................ 274
Reasons for Startup/Shutdown BSOD............................................ 275
Last Known Good Configuration............................................ 275
System Restore......................................................................275
Rollback Driver....................................................................... 275
Safe Mode.............................................................................. 275
Hardware Diagnostics Utility.................................................. 275
UEFI Bios diagnostics (built-in).............................................. 275
Spinning Ball of Death (Mac OS especially)....................................275
Possible Reasons are Many....................................................... 275
Application Bug...................................................................... 276
Bad hardware......................................................................... 276
Slow paging to/from disk – virtual memory.............................276
Solution: consult Console logs to determine cause................276
Black Screen................................................................................... 276
Monitor plugs..........................................................................276
Input Selection........................................................................276
Case: Image is also Dim............................................................. 276
Brightness controls.................................................................276
Swap Out Monitors..................................................................... 277
Goes Black once Windows loads................................................277
VGA Mode (F8)...................................................................... 277
No Power.........................................................................................277
Multimeter - AC...................................................................... 277
Multimeter - DC...................................................................... 277
Motherboard or Case fans?....................................................277
Fans spinning......................................................................... 278
Sluggish Performance..................................................................... 278
Task Manager.........................................................................278
Performance (tab).................................................................. 278
Disk Space..................................................................................278
Defragmentation.....................................................................278
Power-Saving Mode (unplugged Laptop)................................... 278
CPU Throttling........................................................................278
Temperature Rises................................................................. 278
Anti-virus / Malware................................................................... 279
Overheating..................................................................................... 279
Cooling Systems......................................................................... 279
Fans & Airflow........................................................................ 279
Heatsinks................................................................................279
Temp Sensors........................................................................ 279
Temp Monitoring Software.......................................................... 279
Dust covering vents, expansion slots..........................................279
Smoke and Burning Smell............................................................... 280
Visual inspection.................................................................... 280
Intermittent Shutdown......................................................................280
Check Windows Event Viewer............................................... 280
Excessive Heat........................................................................... 280
Failing Hardware.........................................................................280
Device Manager..................................................................... 280
Trial-and-Error........................................................................ 281
Application Crashes.........................................................................281
Event Log............................................................................... 281
Reliability Monitor (Windows)................................................. 281
Solution: Uninstall Program and Reinstall Latest Version...... 282
Grinding Noises............................................................................... 282
Loose Components................................................................ 282
Hard drive failing.................................................................... 283
Fan blockages........................................................................ 283
Blown Capacitor..................................................................... 283
Solution: Replacement of the capacitors................................283
Freezing / Lockups.......................................................................... 285
Check for other indicators / activity........................................ 286
Recent system changes - Drivers? Patches?........................ 286
Low Resources.......................................................................286
Hardware Diagnostics............................................................ 286
Continuous Reboots........................................................................ 286
Observe Extent of the Boot Process...........................................286
BIOS only............................................................................... 286
OS Splash screen.................................................................. 286
Previous Boot Configurations..................................................... 286
Boot from last known working config (F8).............................. 286
Safe Mode (F8)...................................................................... 286
System Properties (Config).................................................... 287
Detail and Document everything on Freeze Screen...............287
Bad Hardware............................................................................. 287
Inaccurate System Date/Time......................................................... 287
Bad motherboard battery............................................................ 287
Replace CMOS battery.......................................................... 287
Manually Resetting Date/Time continuously.......................... 287
Bios Reset...................................................................................287
Jumper the Mobo and Restart................................................287
TROUBLESHOOTING STORAGE DEVICES......................................288
Storage Failure Symptoms.............................................................. 288
Read/Write failure message........................................................288
Slow Performance - Still Working............................................... 288
Loud Clicking Noise.................................................................... 288
Responding to Disk Failures............................................................288
Get a Backup immediately.......................................................... 288
Check for loose / damaged cables..............................................288
Check for overheating.................................................................288
Check PSU................................................................................. 289
Run hard drive diagnostics......................................................... 289
Boot Failure Symptoms................................................................... 289
“Drive not recognized” “Boot device not found”.......................... 289
Operating System not Found...................................................... 289
Responding to Boot Failures........................................................... 289
Check cables.............................................................................. 289
Check boot sequence in BIOS....................................................289
New Installation? Check hardware physical config.....................290
Try the drive in a different computer........................................... 290
Data Loss/Corruption.......................................................................290
Hard drives = mechanical devices.............................................. 290
3rd party data recovery company...........................................290
SSD stops working......................................................................290
Data Loss Solution = Backups.........................................................290
RAID Not Found.............................................................................. 290
Missing or Faulty RAID Controller...............................................291
RAID Disk Stops Working........................................................... 291
RAID Manager........................................................................291
RAID Recovery................................................................................291
S.M.A.R.T........................................................................................ 292
Self-Monitoring Analysis & Reporting Technology..................292
Avoiding Failures in the first Place..............................................292
Tie to Automatic Data Monitoring / Alerts from System..........292
Schedule Disk checks.................................................................292
Warning signs............................................................................. 292
Extended Read/Write times............................................................. 293
Complex System interactions..................................................... 293
Memory access...................................................................... 293
Cross bus communication...................................................... 293
Spinning drive access............................................................ 293
Writing / reading data to different types of storage devices... 293
Standard Measure of Storage Device Access / Performance.....293
Input/Output Operations per Second (IOPS)..........................293
Missing drives in OS........................................................................293
OS boots normally...................................................................... 293
Internal drive solutions................................................................ 294
Loose or missing cables.........................................................294
Reseat the m.2 drive on Mobo............................................... 294
Replace drive because it has failed........................................294
External drive solutions...............................................................294
No power to the drive or bad connection................................294
CHeck proper USB interface is being used............................294
Network shares........................................................................... 294
Missed connection at Startup?............................................... 294
TROUBLESHOOTING VIDEO AND DISPLAY ISSUES...................... 294
No Video Image / No signal............................................................. 294
Check both Power & Signal cable...............................................294
Switch through different Input interfaces.....................................295
Image is Dim....................................................................................295
Check Brightness / Contrast controls first...................................295
Swap the Monitor out to another System........................................ 295
Failed Monitor............................................................................. 295
No Video after Windows loads........................................................ 295
Start in VGA mode (F8).............................................................. 295
Image Quality problems...................................................................295
Flickering color patterns incorrect etc......................................... 295
Check the cable itself + Pins on connector (VGA)................. 295
Missing Colors are an extra clue to that................................. 295
Distorted image and geometry....................................................296
Refresh rate & Resolution compatible?..................................296
Disable hardware acceleration............................................... 296
Native Resolution............................................................................ 296
Blocky letters / bleeding in output............................................... 296
Best picture = matching Native Res....................................... 296
Aspect Ratio must at last match.............................................296
Burn-In.............................................................................................296
Pixel-Shift............................................................................... 297
Image Sticking............................................................................ 297
Remove by displaying white screen for extended period of time.
297
Dead Pixels..................................................................................... 297
Not a cable issue, or power........................................................ 297
Clean the monitor screen to eliminate dust as a possibility........ 297
Damp cloth that wont scratch screen..................................... 297
Replace entire display.................................................................297
Flashing screen............................................................................... 297
CHeck the video cable connnections..........................................297
Proble could be the monitor........................................................ 298
Confirm OS display settings first to rule this out.....................298
Incorrect Display Color.................................................................... 298
Check Tint in Monitor settings.....................................................298
Perform factory reset of monitor config.......................................298
Driver on OS - any tint or color mode settings there...................298
Check OS in case it has red-eye / night mode coloring.............. 298
Audio Issues w/ Monitors – no sound / low volume.........................298
Controls for audio on Monitor? Check volume / Mute.................299
Confirm audio feed Input to the Monitor......................................299
HDMI...................................................................................... 299
Thunderbolt............................................................................ 299
DisplayPort............................................................................. 299
Check for Audio Jacks................................................................ 299
Analog.................................................................................... 299
Digital..................................................................................... 299
INtegrated...............................................................................299
Dim Image....................................................................................... 299
Check monitor brightnes/ contrast settings.................................299
Check the OS – Modify in Driver settings................................... 299
Auto-dimming / time of day.....................................................299
Dim on Battery Power............................................................ 299
Display seems black but almost visible behind it........................ 300
Backlight failure...................................................................... 300
Even only a section of screen could be out............................300
LCD Projector Troubleshooting....................................................... 300
Metal-Halide lamp.................................................................. 300
Always leave the fan running when you turn off......................... 300
Intermittently Shuts Down........................................................... 300
COoling Problem?.................................................................. 301
Check cooling vents, is Fan Running?................................... 301
Temperature Sensors inside blocked?................................... 301
Air filters need replacing?.......................................................301
TROUBLESHOOTING MOBILE DEVICES..........................................301
Poor Battery Health......................................................................... 301
Replace aging batteries.............................................................. 301
Bad Reception............................................................................ 301
Use Airplane mode on the ground..........................................301
Disable unnecessary features.....................................................301
Additional services disabled - 802.11, BT, GPS radios.......... 301
Check Application usage............................................................ 301
Check Application Battery Usage...........................................302
Swollen Battery................................................................................302
DO NOT open the battery packet / container......................... 302
Faulty Battery..............................................................................302
Dispose of properly - HAZ WASTE facility............................. 302
Broken Screen.................................................................................303
Perform Backup......................................................................303
Replacing the Screen..................................................................303
Use tape to hold broken bits in place – prolong use temporarily..
303
Improper Charging...........................................................................303
Check Cable Interface................................................................ 303
Remove any obstructions from port....................................... 303
Check the Cable......................................................................... 303
Try a known-good cable......................................................... 303
Verify the Power Adapter specs..................................................304
Are voltages from AC source and output voltage correct?.....304
Poor or Zero Connectivity................................................................304
Hint: Location is everything.................................................... 304
Cellular........................................................................................304
Signal Strength meter.............................................................304
Is Outdoor connectivity better?...............................................304
Wi-Fi............................................................................................304
Distance................................................................................. 304
Config a different Channel/Freq – unimpeded bandwidth...... 304
Liquid Damage................................................................................ 304
Liquid Contact Indicator - LCI.................................................304
Power down and strip device immediately..................................305
Remove all components possible...........................................305
Rice doesn’t really work – Use Silica gel instead........................305
Desiccants..............................................................................305
Don’t disturb or do anything with it while water inside................ 305
Wait at least 1 day minimum in a very dry area.......................... 305
Once you’re sure Power On again..............................................305
Overheating..................................................................................... 305
Temperature Sensors............................................................. 305
Common heat causes................................................................. 306
Check the Apps usage................................................................306
Application Resource Usage utility.........................................306
Avoid Direct Sunlight...................................................................306
Digitizer Issues................................................................................ 306
Need to do a Reset..................................................................... 306
iOS reset – Press power button, slide to power off, press power
button..................................................................................... 306
… Hard reset – Hold down power + Home + Vol for 10 seconds.
306
Android reset – Remove battery, put back in, power on.........307
… Hard reset – Hold down power and vol until restart...........307
Physically Damaged Ports...............................................................307
Accidents? Tripping cable, bent connecter, rough handling....... 307
Not charging? Do a visual inspection..........................................307
Replacement is troublesome – integrated onto system board....307
Malware........................................................................................... 307
Look for Symptoms a new malignant app is running.................. 307
Strange apps we never isnatlled............................................ 307
Large Data transfers...............................................................307
Pop up messages...................................................................307
High CPU usage / overheating abnormally............................ 307
Battery continually depleted sooner....................................... 307
Try a security App or scanner..................................................... 308
3rd-Party Virus Scanner......................................................... 308
Cursor drift.......................................................................................308
Common on Older screens.................................................... 308
Use a Touch calibration app........................................................308
Should solve cursor drift.........................................................308
TROUBLESHOOTING PRINTERS......................................................308
Testing the Printer............................................................................308
Printer Settings or Properties tab................................................308
Determines Windows config is correct................................... 308
Connection between Device and Printer is working............... 308
Printer itself is functioning fully............................................... 308
Diagnostics in Printer.................................................................. 309
Test functions built into printer................................................309
Web-based utilities................................................................. 309
Vendor specific....................................................................... 309
Generic utilities.......................................................................309
Issues with Test Page Output.......................................................... 310
Inkjet + Vertical line showing down page.................................... 310
Time to clean Print Heads / Replace Print Heads.................. 310
Laser + Vertical line down page.................................................. 310
Scratch on Photosensitive Drum - Needs replacing this (w/
Cart?)..................................................................................... 310
Faded printing, blank entirely......................................................310
Fill toner (laser)...................................................................... 310
Fill ink (inkjet)......................................................................... 310
Doubling / Echo images or speckling..........................................310
Laser - Optical drum not self-cleaning properly......................310
Garbled print............................................................................... 310
Wrong printer Driver / Wrong model?.....................................310
Test print from printer itself (internal)...................................... 311
Troubleshoot the application after – correct printer model..... 311
Toner not sticking to paper – smudging on touch........................311
Fuser may not be heating it up or working properly............... 311
Unhook and slide Fuser Assembly out of printer, and replace.....
311
Incorrect Size Paper........................................................................ 311
Printer Stops – Paper Tray notification........................................311
Replace the paper in that tray................................................ 311
Modify configuration on device to match the printers’............ 311
Paper Jam....................................................................................... 311
Remove Paper while carefully not leaving any behind............... 312
Picking up incorrectly.................................................................. 312
Pick up multiple...........................................................................312
Check Paper Tray for proper function, no damage................ 312
Check out Pickup Rollers, observe a single page passing.....312
Replace rollers individually or as part of Maintenance Kit......312
Papers are creased upon exist................................................... 312
Some defect along rolling path...............................................312
Wrong weight of Paper...........................................................312
Check Documentation for Printer to get optimal suggestion.. 312
Multiple Prints Stopped in Queue.................................................... 312
Print Spooler crashing.................................................................312
IF it fails the 1st and 2nd time.. This is automatic.................. 313
IF it fails beyond that, Service will take no action / no restart.313
Continued Spooler Crashing Issues........................................... 313
Windows Event Viewer...........................................................313
Look for Windows Print Service tagged events......................313
Single Print Job Can be repeatedly Crashing all prints...............313
Delete this print job.................................................................313
Monitor to verify it was the one causing the issue..................313
Incorrect Color Settings................................................................... 313
Calibration of Screen first – accurate model............................... 313
3rd-Party Calibration = more certain though – accurate and
professional............................................................................ 313
Check the Paper – bright white...................................................313
Calibrate the Print Color..............................................................313
Tool for Balancing proper amounts of ink / toner....................314
Grinding Noises............................................................................... 314
Paper jammed inside Printer Path?............................................ 314
Carriage (Inkjet) stuck on rail / blocked from moving across Page...
314
Different process for Removal of Jams or Mechanical Solutions314
Check Documentation for Printer to find the correct process.314
May require additional Maintenance / Repair order from Outside....
314
Order replacement parts........................................................ 314
Replace entire printer............................................................. 314
Relatively Simpler fixes too.........................................................314
Someone just replaced Ink cartridges incorrectly – Reseat them
314
Finishing Issues...............................................................................314
Collate, Bind, Staple, etc.............................................................314
Staple Jams................................................................................ 314
Each Manuf. Has different removal process for Stapler /
Cleaning................................................................................. 315
Hole-punching location............................................................... 315
Check print driver that correct settings were inputed............. 315
Check that they match configuration of the printer.................315
Page Orientation..............................................................................315
Wrong Selection given to Print Driver......................................... 315
Print Driver is defective............................................................... 315
Update....................................................................................315
Printer has a Default preference................................................. 315
Check the settings on the printer console.............................. 315
TROUBLESHOOTING NETWORKS................................................... 315
No Network Connectivity................................................................. 315
Link Light (Traffic indicator LED).................................................316
Check Light from the Switch...................................................316
Connected? Test How far comms can get along Network.......... 316
Ping the loopback IP address (device’s internal IP) - 127.0.0.1...
316
Basic Sucess = Protocol stack working..................................316
Variation = Availability and Intermittency of Connectivity?..... 316
Ping local IP address of NIC....................................................... 316
Physical adapter is working? Config is working? Connected to
Network?................................................................................ 316
Ping Default Gateway – Network’s External Interface................ 316
Def Gateway responds?.........................................................316
Connected to Internet? Ping a major server on the internet....... 317
Ping devices on Router’s other side – 8.8.8.8 / 1.1.1.1 / 9.9.9.9..
317
Intermittent Wireless Connectivity................................................... 317
Band Interference causing Packet loss or Ping dropouts........... 317
Check Signal Strength on Device – close enough Distance? 317
Transmitting Antenna good?.................................................. 317
Transmitting Signal good?......................................................317
Receiving Antenna good?...................................................... 317
Best Channels for communication in WAP................................. 317
Check Freqs config’d in WAP – Manual tuning or Automatic?.....
318
Manually config different channels – performance improves?.....
318
Signal Bounce and Latency - physical barriers / materials......... 318
Check for multipath interference / Flat surfaces.....................318
Move to better point................................................................318
Incorrect Access Point placement...............................................318
Need closer location toward Users?.......................................318
Move Users towards it?..........................................................318
Wireless Interference Analysis........................................................ 318
Predictable Sources of Interference............................................318
FLueorescent lights................................................................ 318
Microwave ovens....................................................................318
Cordless phons...................................................................... 318
High-power sources............................................................... 318
Unpredictable Sources / Uncontrollable / Public Areas.............. 318
Use simple Utility measuring using SNR (signal-to-noise ratio)...
319
Use Performance Monitor (Windows) to break that out in more
detail.......................................................................................319
Signal to Noise............................................................................319
Ratio is the critical factor........................................................ 319
Limited or No Connectivity (per Windows system data).................. 319
System Tray (Windows)......................................................... 319
Check Local IP Address..............................................................320
Check if it has been assigned by DHCP and/or Manually
preconfig’d..............................................................................320
APIPA address? DHCP process failed – local connectivity only..
320
DHCP addy obtained? Perform the Regular Ping Tests............. 320
Check local gateway, Remote IP address (i.e. DNS)............. 320
Jitter – Delay-based Loss or Distortion of Real-Time comms..........320
Missed packets are gone – no retransmission............................320
Are subsequent packets getting through okay now?..............320
Jitter - useful Statistic to observe the quality...............................320
Time between frames............................................................. 320
Improving Poor VoIP quality........................................................320
Configure for High Speed & Low Latency for best results......321
Check if anyone else using Bandwidth on our shared
connection.............................................................................. 321
Verify Local Networking equipment – age, condition? Replace?.
321
Packet Capture – View the network Performance..................321
Latency............................................................................................ 321
Examine the Response Times at every step along the way....... 321
Measuring each Network along the way – what Latency is
normal?.................................................................................. 321
Packet Captures – detailed and granular analysis of both-way
traffic.......................................................................................321
How much time is occurring from 1 frame to another?...........321
Port Flapping................................................................................... 321
NIC / Link light turning on & off repeatedly................................. 322
Port Flapping – some physical issue in between 2 devices... 322
Check the physical Media themselves........................................322
Cable tester – can it support the used Speeds / Standards?. 322
Replace the Cable if that was it..............................................322
Check the Hardware................................................................... 322
CHeck after moving to different interface on device (Switch).322
Issue is NOT the Switch if the problem follows on other
Interfaces................................................................................322
Change out your computer or Network Interface Card...........322
Change out Cable here too if necessary for certainty............ 322
- - - - - - DEVICES - - - - - LAPTOPS
Defining characteristics - Hardware + Parts
Precise specifications… designed for unique form factor
Tendency to develop repair expertise with particular brand
(similar to automobiles)
Battery
Modular (replaceable)
Fixed (inside)
Lithium-ion // Li Po (polymer)
Diminishing capacity after each charge
Form is model-specific,
Tech advances regularly, so not backwards compatible
Can have backup, swappable batteries
Keyboard
Single piece w/ Ribbon cable connector
+ External USB keyboard in case onboard doesn’t work
Space economized (Fn / combo 2ndary functions)
Keycaps may be replaceable but force and weight varies
So follow manufacturers instructions carefully
Memory
SO-DIMM
small outline dual in-line (common form)
Usually accessible from door on bottom of laptop
Integrated
For non-changeable it is usually Soldered onto MB
Requires full system board replacement
Storage
Hard Drive
magnetic disk (common 2.5” form)
Spinning physical drives
SSD
solid state (same 2.5” form and SATA connectivity)
No moving parts inside
Greatly increased R/W speed
M.2 interface (smaller form)
Takes up less space
Modular, additive storage
Plug into slot and screw in
Drive Replacement
Entire back cover removal // Back window access
Regular – Screw removal – cable removal – slide out
M.2 – single screw – slides out directly
Data Migration
Move OS from HDD to SSD
Install on SSD and move data over after
Time consuming.. Requires nd OS install
Manual app installs, data transfer
Clone image of HDD onto SSD
No new install required
Moving everything, data, apps, at once
Requires SW to do the image clone
Manuf. (bundled) and Open Source
Requires 2 systems // 2 drives in 1 system
Wireless and Bluetooth
802.11 and BT built into system board
(older laptops) PCI / PCIe interfaces to add cards
WWAN (cellular), LAN, PAN (personal/BT)
Access via a back cover
Biometrics
Unlock using fingerprint or facial recognition
More secure and hard to forge
Requires 1) SW/OS auth tools 2) HW to read input
Additional config in OS to improve security
“Windows Hello Face”
“Window Hello Fingerprint”
NFC
Short distance networking
Transfer without physically touching device
Useful for authenticating to a laptop also (credential)
Displays
LCD
crystal filters that are backlit
Lightweight, use less power, cheap to manuf.
BUT constant light src makes “true black” impossible
Difficult to repair or replace backlight layer
3 types of LCD
TN
(twisted nematic)
+Response times, fast moving graphics
–Limited viewing angles
IPS
(in plane switching)
+Color representation
–expensive to make
VA
(vertical alignment)
Okay color rep
—response times are slower
OLED (organic LED)
Org compound emits light when current applied
Thinner *lighter, flexible (no glass required)
No backlight
+color representation, light
- higher cost
Very popular on Phones/Tabs/Smart devices
Microwave Antenna
Basis for Multiple antennae?
Wifi main and Aux
BT
Radios are challenge when replacing a display
Must ensure same wire path and connection
(additional wires for Camera, mic)
Webcam
Usually integrated into laptop
Meetings/Calls, video capture
Backlights
…Fluorescent vs. LED
CCFL
(cold cathode)
Higher voltage – Use more power
(Older laptops)
Inverters behind screen (AC powered)
LED
(newer, used on LCD too) around edge or matrix
Thinner
Matrix behind the LCD looks like strips
Replacement
Detect failure by illuminating screen from front (flashlight)
If information shows throw then only backlight is bad
Replace backlight
Digitizer
…(hybrid devices – keyboard+tablet)
Hi-res input using stylus directly onto screen
Pressure creates digital signals on the display
Two types:
Stylus only
Touch-screen
MOBILE DEVICES
Connectivity
…Comms, Syncing, backup, Identification
Wired
USB
– high speed
Charging + data transfers
Mini B (older devices – squarish)
Micro B (more common)
USB-C (current)
Replaces Type A on computers too
Display port signals, HDMI A/V, thunderbolt.. etc.
Reversible
Lightning 8-pin (Apple – iPhone iPad)
Charges faster
Reversible
Simpler design
DB-9 serial (pre-USB)
Common for RS-232 signals (since 1969)
Modems especially
(Now) View consoles for Router, Switch, Firewall
Wireless
NFC
(small transfers, close distance, trusted)
Payment/transaction details
Access device or ID card
BT
(home distance, automobile)
Wifi Hotspot
(personal wireless router)
Input / Output
Touch pen / Touchscreen stylus / Capacitive stylus
Activate interface w/o actually touching it
View screen still while writing on it
Basic Handwriting
Signing documents, taking notches
Active stylus (digital stylus)
– common w Artists
More functionality, usability
Communicates independently with device
Pressure sensitive
Additional functions from Button on pen
Corresponds to specific device usually
e.g. Apple Pencil w/ iPad
External drawing pad
+ active stylus for computer
Trackpad
(common on laptops)
Replaces the mouse, move things around on screen)
External trackpad
(computers)
Customizable for different finger moves/presses
**disabling inadvertent keypresses on trackpad**
2-way Headsets
– Mic input + earphone
USB wired
3.5mm TRRS (tip ring ring sleeve)
Lightning port
BT headset
Speakers
– external
Battery powered (Wireless / BT)
+fuller Stereo sound vs. onboard in a small package
Docking station
Use external keyboard / mouse / display
Extend interfaces.. Usb, etc
Added functionality
Adaptor card extension
Avoid cables
Port replicator
– normally USB, LAN, A/V
Simpler than dock connecting
-No expansion card options
+smaller, fast and mobile
Cellular Networks
Land geography subdivided into “Cells” by antennas
Generations:
2G (original)
2 global standards:
GSM (global system for mob comms) ~ 90% of market
Standard in Europe/ATT/TMo
Allows SIM (subscriber identity module)
Used multiplexing to allow high/mixed traffic
CDMA (code division multiple access)
Call data separated by code/filter
Verizon/Sprint, unpopular elsewhere
Good voice quality but limited data support
Circuit switch networks needing MUCH upgrade
3G (1998)
Incremental speed improvement (1-2 MB/s)
Bandwidth improvement
Allowed new functionality.. On-Demand, Streaming, GPS
4G / LTE
“Long Term Evolution” 1 standard introduced to converge
GSM/CDMA
combined with EDGE (Enhanced Data rates for GSM Evolution)
Increased throughput to 150 Mb/s
LTE-A (advanced) doubled speeds to 300 Mb
5G (2020)
Using higher frequencies radio waves
Improved speeds up to 10 Gb/s ~ 100-900 Mb initially
IoT (Internet of Things) enabling extension of device functionality
Larger file transfers, increase app capability, more cloud
reliance
PRL
(Preferred Roaming List)
Allow phone to understand where are appropriate towers to use
OTA (Over The Air) updates occur in OS when List needs changing
Wifi Hotspot
Merge mobile data network with a 802.11 network
Phone becomes a data router allowing nearby devices to use internet
Providers often limit/condition functionality of this feature
Bluetooth
1)
2)
3)
4)
5)
Pairing process for mobile phones, tablets + other devices
only required to perform once, to authenticate
automatically network with each other afterward
Allows you to control what devices can talk to your device
View or verify a passphrase or PIN
Ensures you have physical control of both devices
Sequence and discoverability varies with manufacturer
General process:
Make sure both devices are enabled to use Bluetooth
Can sometimes be disabled by default
Make both devices discoverable
Menu option… hard button press… etc.
Select from list of discoverable devices in area
(optional) Confirm or enter PIN
Test connectivity
GPS
Global Positioning System
30+ satellite network by DoD
Signal from 4+ satellites needed to get accurate location
Phone calculates based on time difference in signals
Longitude, Latitude, Altitude
managed by Mobile device Location services & Geotracking
Used in apps like Maps, directions,..
More accurate with other Location data like Wifi, Cell towers
MDM
Mobile Device Management
Large orgs use to administer company device network
Includes BYOD (Bring your own Device) users’ phones
Access config + control all devices from central console
especially important if company Data stored locally
manage security, update config settings collectively
install needed apps, manage capabilities (e.g. camera)
Partition company data and protect separate from private data
delete or remove with affecting personal apps / data
require added security features.. e.g. lock screen, PIN
User doesn’t have to manually configure any company apps
Email, filesharing, other configs can all be Pushed via MDM
Changes can be pushed from the console as well
Boost security of devices
Require 2FA, biometrics
Push supporting apps for these features like keygens, etc.
Control available apps on phone
automatically install required apps for company use
prevent unauthorized apps that could compromise device
Mobile Device Configuration
Basic factory services: Phone calls, Text
Others need config: Email, Cloud storage, Sync
Microsoft 365 (aka Exchange / Outlook / Hotmail )
Used to communicate inside orgs
Requires authentication to access services
Email + other items you can sync
Contacts.. Calendar.. Notes.. Tasks
Sync across desktop, mobile devices, etc
Google Workspace (fka G Suite) ~ same process
iCloud ~ similar
within Apple devices, included in iOS / iPadOS
sync most app data between devices + macOS
constantly backing up data in cloud
restore lost data to new device
Allow more extensive configuration of Sync
Data types, Data Transfer caps & networks
- - - - - NETWORKING - - - - NETWORK PROTOCOLS
IP
Internet Protocol
(model) moving around large amounts of information in “boxes”
Network topology is the “road” it moves along
IP is the “truck” that roads were designed for
moving efficiently from point-to-point
UDP and TCP are the types of “boxes”
Doesn’t know what’s in boxes, just getting it onto truck
Packs up your data inside them, unloads on arrival
Information inside specific to certain “room” at destination
graphically… Client is sending, Server receiving:
[eth header |||| → eth Payload ← | eth trailer]
… contains:
[ IP head |||| → IP payload ]
…. contains:
[ TCP head |||| → TCP payload ]
….contains:
HTTP data
Transport Layer
breaking down an IP packet into TCP/UDP…
TCP vs. UDP depends on application feature
aka “Transport” / OSI Layer 4
they are “encapsulated” within IP
way to transport data from one part of net to another
technically IP would be sufficient to do this
BUT these add capabilities it can’t provide:
Multiplexing.. many apps simultaneously
Client sending multiple app info
Server determines which apps are in use
TCP
Transmission Control Protocol
it is “Connection-oriented”
formal process setting up flow from A → B
+ … tearing that flow down when done
“Reliable” delivery
(not better or faster)
Verification that Sent data was Received is built in
Can Reorder messages received out of order
possible error when multiple links to same location
Can manage a Retransmission process
Any data not received can be resent from source
Flow control
Device can slow down process if receiving too quickly
UDP
User Datagram Protocol
“Connectionless”
no formal process to open or close flow of data
simply starts sending from A → B
“Unreliable” b/c there’s no acknowledgement or receipt
No Flow control
Receiver cannot regulate, it is a one-way conversation
…still important for sending info quickly over network
+Real-Time Communication
best in cases where you can’t stop, retransmit, or catch up
(similar to a phone call, you can’t rewind the tape)
Simply send data and it’s received or dropped
Conversation keeps going regardless
Connectionless protocols
DHCP
(Dynamic Host Config Protocol)
automatically assign IPs to devices
TFTP
(Trivial File Transfer Protocol)
Application is responsible for keeping track of receipt
e.g. DHCP would do this by tracking sends/response
.. resend if unsuccessful
Connection-oriented protocols
..taking advantage of “return receipt” function of TCP
HTTPS
(Hypertext Transfer Protocol Secure)
commonly used in web browser
SSH
(Secure Shell)
encrypted terminal to terminal communication
Application doesn’t worry about lost data / out of order frames
e.g. HTTPS data lost, TCP recognizes, requests retransmit
.. SSH/HTTPS don’t have to manage that process
IP Addresses, Ports, Sockets
IP
delivery truck delivers from one address (house address) to another
IP addresses are unique to each device
Boxes received at next house
Next step is reading label further to see which “Room” info goes to
Port number
i.e. “what Service on device will be receiving that data”
written on outside of box so it can be directed at entry to house
e.g. services send data from same address on 25, 80, 123, 443
Allows Multiplexing
Front door is receiving and directing a lot of boxes at once
Makes sure it gets to the right app
IPv4 Sockets
Needed info to complete traffic flow between A → B
Server IP Address
Protocol (e.g. TCP)
Server application Port Number
Client IP Address
Protocol (e.g. TCP)
Client Port Number
Important that servers using well-known ports
e.g.
Client browser communicating with server via 80, 443 (HTTPS)
Non-ephemeral ports
… Permanent port numbers that are same across all comms
common on servers / services
usually in 0–1023 … common usage is what matters most
Ephemeral ports
… Temporary port numbers
association created by client device for a particular traffic flow
no longer used once traffic flow is over
OS configs these
assigned in real-time while using Apps
usually in 1024–65,535
TCP/UDP can use anything in 0-65535
Not all major apps use known ports
Some use Dynamic ports, change from device to device
Ports are necessary for communication, not security
Using a less common port number doesn’t “hide” anything
Designed simply to allow access of services on a given device
Port scanners can easily find all open ports on a computer
Then start probing services on those ports
Known ports on Server side applications ARE important
All internet websites are using the same port
Otherwise we’d need to scan ports for each web address
TCP has its own set of port numbers, different than UDP
i.e. TCP 80 and UDP 80 can each have a service running
32-bitCommon Port Numbers
Services use specific ports to allow incoming connections
Client + Server have same expectation of send/receiving ports
Firewall’s forwarding rules to allow incoming/outgoing traffic
Must know port number + Protocol (TCP/UDP) for the application
FTP
tcp/20
data
tcp/21
transfer control
Requires some type of auth (e.g. U/P, can be anonymous though)
Additional File management functions (terminal/db commands)
Add, delete, list, rename, etc.
SSH
tcp/22
Secure Shell works similar to telnet
Access remote device from text based CLI
Actual commands sent between devices are encrypted
Telnet
tcp/23
Telecomm Network Protocol
Connect to remote console of another device
Unencrypted messages, can be seen by packet sniffers
(Never use on production network!!)
SMTP
tcp/25
Simple Mail Transfer Protocol
Sending mail to server by Client
Moving mail server to server
(Receiving is done on separate protocols IMAP, POP3)
DNS
udp/53
Domain Name System
Resolve an IP address from text-based Web address
how to reach out to an actual server for website requests
DHCP
udp/67
udp/68
Dynamic Host Configuration Protocol
Server (router/WAP) assigns IP addresses to network devices
Occurs in real time, dynamically
IPs leased from a pool of possible IPs, renewed regularly
Reservation - admin can assign static IP to some devices
Based on known MAC address
HTTP
tcp/80
Hypertext Transfer Protocol
tcp/443
Hypertext Transfer Protocol Secure
encrypted
tcp/110
Post Office Protocol v3
Designed to retrieve email into a fixed mailbox (non-mirrored)
POP3 & IMAP4
Authenticate and transfering functions from mail server
Clients receiving mail only
tcp/143
Internet Message Access Protocol v4
Sync and manage email inbox across multiple clients
SMB – (OS-specific)
Server Message Block (aka CIFS Common Internet File System)
File + Printer sharing between computers
Uses various protocols to communicate:
NetBIOS (older Windows)
udp/137
nbname
Name service; Find networked computers by name
tcp/139
nbsession
Create session + transfer data
NetBIOS-less (modern Windows)
tcp/445
Direct SMB, device to device using only TCP/IP
SNMP
Simple Network Management Protocol
check status of Infra devices per performance metrics
config devices to monitor for certain metrics
udp/161
SNMP Queries
send request to infra device(s)
udp/162
SNMP Traps
receive alerts from device when metrics exceeded
Version 1 (original)
Structured info sent over network – unencrypted
Version 2
Allowed Bulk transfers – unencrypted
Version 3 (current standard)
Secure
Message integrity, authentication – encrypted data
LDAP
tcp/389
Lightweight Directory Access Protocol
Query and add information on a network directory
Directory stored on server
Microsoft Active Directory (popular implementation
RDP
tcp/3389
Remote Desktop/GUI access to external device
Connect / Receive an RDP session
Take over entire system
Control a single application on server
Installed for most Windows OS by default
Servers are essentially only Window boxes
Clients for accessing exist across platforms
Mac, Linux, UIInix, Android, etc.
NETWORK DEVICES
Single-use vs Combined function
e.g. Switch (single), Wifi Modem-Router (multiple)
Router (Layer 3 Device)
Forwards traffic between different IP Subnets
uses IP address inside packet to determine next hop
“Layer 3” also applies if router configured inside a Switch
Can connect different types of networks together
e.g. LAN, WAN, copper, fiber... simultaneously
Switch (Layer 2 device?)
Forwards traffic based on MAC address
Using data link address inside that frame
Faster because decision is made in hardware
Application-specific integrated circuit (ASIC)
Allows very fast throughput
Enterprise networks:
Core switches may contain 10-100s of interfaces
May also be power-boosted
POE – Power over Ethernet
Multilayer Switch
Layer 3 functionality – can turn on addt’l Routing function
Unmanaged Switch (Fixed Configuration)
Simple device connectivity
Few config options (plug n play)
Not appropriate for Enterprise
No VLANs (Virtual)
Not much Integration with Devices / Protocols
No management protocols
e.g. SNMP
Can connect network
Cannot monitor network, query devices
Low price point
Managed Switch (Multi-functioning)
Allows interconnection w/ other switches via 802.1Q
Ideal when constant performance monitoring needed
Interfaces can be individually config’d
i.e. put on different IP subnets – VLANs
Prioritize traffic
.e.g. VoIP > FTP
Redundancy support
Connect multiple switches in network
STP prevent loops from occurring
Spanning Tree Protocol
Port Mirroring
Copy traffic from one port on switch to another
Plug in Protocol Analyzer on 2nd port
Allows packet analysis
Commonly uses in troubleshooting
External Management via SNMP
Access point
“Bridge” – linking wireless devices to the wired network
Analogous to a Switch – forwards based on MAC address
NOT a Layer 3 device
Not routing between different subnets
Not translating network addresses
Wireless router is combination access point + router
Cable infra
Physical cables
= huge management problem for large orgs
Patch Panel
Spatially-Organized by Blocks
permanently run cables from desk unit to panel
Tied to the workspace, not the person in it
Reroute on panel backend if new occupant
Limits problems that could occur from changes
RJ45
Ethernet cables out from Patch panel
Extend to interfaces on e.g. Switch, other device in closet
Connect desk back to main network infra
Firewall (Layer 4 device)
Allow/disallows network traffic by IP and Port Number
TCP/UDP port recognition makes this an OSI - L4 device
Now common to understand Application traffic too - L7 device
Encrypted tunnel Endpoints
Connect 2 sites together across internet (public network)
Proxy
Intermediate internet browsing activity
Stop direct comms – perform actions, receive response
Checking malicious/dangerous contents inside traffic
Anonymize + Safeguard results back to user
Routing (L3 functionality)
Forwarding based on destination IP
Common on small network /home router combos
Ingress / Egress – sits directly on connection to Internet
convenient place for additional forwarding functionality
Power over Ethernet (PoE)
Connected devices receiving phantom power over network cable
Single wire contains signal + power source
e.g. access points, cameras, etc. where convenience
Endspan
– Built-in power, coming directly from switch
Midspan
– In-line power, PoE “Injector” run in between
Switches typically indicate where PoE cables are accepted
Different types of power - IEEE 802.3 Standards
(the first 2 are included in current 802.3 standard)
802.3…
af
(2003)
“POE”
15.4 W (DC)
350 mA
at
“POE+”
25.5 W (DC)
600mA
bt
“POE++”
Type 3:
51 W
600 mA
Type 4:
71.3 W
960 mA
**Designed to power devices on 10GBASE-T**
Hub
predecessor to the Switch for connecting network devices
not intelligent
aka “multi-port Repeater”
simply copies any incoming data from one interface to all
very inefficient
only capable of half-duplex communication
slows down exponentially as traffic increases
outdated for modern networks
only available in 10/100 varieties
Cable Modem
Broadband - copper cable
transmission across multiple frequencies
Single wire, different types of traffic
e.g. internet, phone, tv
DOCSIS
standard for sending data over Broadband
“Data Over Cable Service Interface Specification”
High speed flows
up to 1 GB/s
Multiple services outputted
Data link on Modem
Analog phone connecters
ADSL
Asymmetric Digital Subscriber Line
uses existing telephone lines
Distance limited (signal dropoff)
~10,000 ft from Central Office (CO)
Higher download than upload speed
52 Mb Down / 16 Mb Up
possibly faster if near to CO
Optical network terminal
ONT device connected outside the home
Fiber run up to the property
ISP’s network delineated from Internal network
“Demarc” point
where fiber meets copper
Terminal box on outside of building (home)
Inside data center itself (office)
Dictates responsibilities for both parties
Wiring inside is your responsibility
Outputs for Data (ethernet port), phone, cable tv
NIC
the fundamental network device
“Network Interface Card”
Every wired device on the network contains one of these boards
All types of connectivity have these on receiving device
Different styles:
Single or multiple ports
Other topologies
Wide Area (WLAN) serial
Wireless
Adaptors or integrated on main board
Software Defined Networking
aka SDN
Cloud-based, virtualized
classic networking devices change to be software-based platform
Useable in the cloud, distributed
e.g. Switch functionality broken into individual pieces of logic
These devices’ functionality are separated into 3 layers in SDN:
Infrastructure Layer
aka ‘Data plane’
Processing of network frames ~ “packets”
Forwarding
Trunking
Encrypting
Ntwk Address Translation (NAT)
i.e. something else that needs to occur at that packet level
(To forward on) must have reference to traffic’s destination….
Control Layer
aka ‘Control plane’
Contains the destination references of packet
i.e. Manages the actions of the Data plane
Dynamic Routing protocols
Forwarding tables (switch)
Routing tables, NAT table,Session tables (router)
Application Layer
aka ‘Management plane’
Human control of the device, Interface
Log in portal, API access, etc.
SSH, browser GUI, etc.
SDN Description of Physical Device
Extrapolating the physical architecture…
Ex 1: Switch
IFS / Data functions: connect, forward traffic between ports
CTRL functions: tables, forwarding structure
APP / Mgmt functions: console port / mgmt interface, indicators
Modularity of Layers
allows us to extend, share layers between devices
Create new devices from combined functionality
E.g.
Model comms between devices solely on DATA
Swap Routing/Forwarding tables on CTRL
Use SSH, SNMP, API to access MGMT
Allows software-based versions of these devices
Deploy and use in the cloud
WIRELESS STANDARDS
Wireless Networking
aka 802.11 (IEEE’s LAN/MAN standards committee)
~ continuous updates over time
Wi-Fi trademark (WiFi Alliance) ~ tests 802.11a device interoperability
802.11a (original)
Released Oct 1999
5 Ghz exclusively
Able to operate outside that w/ special licensing
Less range than other frequencies
Higher absorption into obstructing materials
54 Mb/s max speed
802.11b (original)
Released Oct 1999
2.4 Ghz
Better range, less absorption
Depending on environment type
e.g. open warehouse may benefit from 802.11a / 5Ghz
11 Mb/s max speed
BUT more conflicts on this bandwidth - other non-Wifi devices
Monitors, microwaves, baby monitors, cordless phones
Bluetooth
Uncommonly used today
802.11g (upgrade to ‘b’)
Released June 2003
Still 2.4 Ghz
conflicting traffic problem remains
Speed boost to 54 Mb/s
Backwards compatible with ‘b’ standard / devices
802.11n (Wi-Fi 4)
Released Oct 2009
Replaced all three former standards
Renamed to ‘WiFi standard’ instead of just numbers
Retroactively changed a, b, g → 1, 2, 3
5 Ghz / 2.4 Ghz
Simultaneous operation (if WAP supports)
+40 Mhz channel widths on each band
Higher data transfer rates
600 Mb/s max throughput (given 40Mh support + 4 antennae)
MIMO
Multiple-Input Multiple-Output (4 total, 1 per channel)
New form of communication for Wireless Networks
Transmitting and receiving on multiple antennas at same time
802.11ac (Wi-Fi 5)
Released Jan 2014
Improved on Wifi 4
5 Ghz only
Less crowded, more freqs
+160 Mhz channel width
More channel bonding
Larger bandwidth usage
More dense Signaling Modulation
Different way of transferring data
Also increased data transfer rates
8 x MU-MIMO downlink streams
MU adds “multi-user” to MIMO
7 Gb/s max throughput
*Some WAPs advertised ‘Wifi 5 / -ac’ still have ‘n’ operation on 2.4 Ghz
802.11ax (current, Wi-Fi 6)
Released Feb 2021
Upgrade to ‘ac’
back to 2.4 + 5 Ghz (simultaneous on some WAPs)
Multiple channel widths
20, 40, 80, 160 Mhz
~10 Gb/s max throughput
marginal improvement over ‘ac’ on speed
1.2 Mb/s per channel x 8 MU-MIMO (bi-directional)
OFDMA
Orthogonal Frequency Division Multiple Access
Different type of comms for high density areas
Imported from Cellular Network design
Maintains efficiency on networks with high number of users
e.g. conventions, stadiums, malls, etc
Antennae / Long-range fixed wireless solutions
Household:
Stock WAP antenna
40 - 50 m range
Corporate Environment (multi-building):
Fixed antenna
increase signal strength
Outdoors:
Directional antenna
Minimal signal absorption or bounce
Point to point, focused on each building’s antenna
Antenna Regulations
usually Complex - refer to country’s reg agency
Frequency use
Seek out Unlicensed (unused) freqs on native 2.4 or 5 Ghz
Additional freqs available?
More licensing may be required
Signal strength
Indoor vs. Outdoor power is normally reg’d
Outdoor antenna installation
Not simple, preferably an expert w/ proper safety
Away from a power source
Protected from lightning strikes
RFID
Radio Frequency Identification
Access badges
Inventory/ assembly line tracking
Pet / Animal ID
anything that needs to be tracked
Cylindrical capsule vs. Flat “chip” design
Cyl - linear, stacked
Flat - chip in center, surrounded by antenna
Powered externally - Radar reflection
No battery inside (normally)
Radio energy transmitted through air to the tag
RF powers the tag, ID is transmitted back
Bi-directional communication
*some formats can have active/powered RFID
NFC
Near Field Communication
common in Mobile phones, Smartwatches, etc.
Builds on RFID –
Two-way wireless communication
Applications:
Physical retail payment systems
Major credit cards
Online wallets
Bootstrap for other Wireless / Bluetooth
Helps with pairing / authentication
Access token – identity “card”
Short range applications w/ encryption support
WIRELESS BROADCAST SPECIFICATIONS
802.11 Technical Specifications
Frequency - 2.4, 5, both, other
Channels - groups of freqs, assigned #’s by IEEE
Non-overlapping is ideal if using Multiple WAPs in 1 area
Regulations - countries dictating spectrum avail/use, signal power
also Interference level allowed on other devices
Band Selection and Bandwidth
Comparing actual traffic on Frequency Bands
2.4G Spectrum for N. America
IEE channel #: 1, 6, 11
20 Mhz bands between 2412 and 2482 Mhz
only 3 available for 802.11, very crowded
5 G Spectrum
IEE channel #: 36-64, 100-165 (available)
68-96, 169-177 (restricted)
(40) Mhz increments
20 Mhz bands on each channel
> 20 Mhz bandwidths possible for higher throughput
40 Mhz / 80 Mhz / 160 Mhz
*only 2 distinct contiguous bands wide enough on 160
Some of the IEEE bands were always available
April 2014
36-48 were opened from indoor-only use to outdoors
New channels added too… 120-128, 144
Bluetooth
Effectively removes wires from home media, I/O devices
e.g. Headsets, Speakers, Keyboard & mouse
Unlicensed ISM portion of 2.4 Ghz band
Industrial, Scientific and Medical
Same as 802.11, doesn’t require any special licensing
Generally communicate in only close personal area - “PAN”
Personal Area Network
~ 10 m
Industrial Bluetooth
additional standards available
> 100 m
NETWORK SERVICES IN THE DATA CENTER
every Data Center has running…
DNS Server
Domain Name System
changes between IP Addresses and Names
Client/browsers interact with webserver this way
a Distributed naming system
Load is balanced across multiple instances on internal servers
Communicating with multiple other servers outside as well
Critical for entire communications process
Managed by local IT dept / ISP
Multiple DNS servers to make sure there’s 100% uptime
DHCP Server
Dynamic Host Configuration Protocol
configures network device IP Addresses automatically
Allows interconnection to anyone’s network, automatic provision of..
IP, DNS settings, everything needed for network comms
Most Home Routers/Cable modems have it too
Server running inside of it
Enterprise IT Dept will need more
Redundancy.. Multiple servers
E.g. Configuration on a home network
“Enable LAN DCHP : true”
“Lease Time : 1 week”
“DHCP Start IP : 10.1.10.10”
“DHCP End UP : 10.1.10.199”
File Server
Centralized storage of docs, spreadsheets, videos, pictures, etc
Folder / file directory structure
Allows filesharing across any device on network
Common ways to communicate with File Server:
SMB – Server Message Block
Windows
AFP – Apple Filing Protocol
Apple
User doesn’t see what protocols are in use
Simple interfacing with file mgmt Front End
Copy
Delete
Rename
etc.
Print Server
connect a printer to the network
Common in Enterprise environments
Centralized location of printer amidst many users
Provide printing service to all network devices
Software running on computer with the actual connection to printer
Hardware card that plugs into printer, extending ethernet to printer
Wireless print server running inside the printer itself, on Wi-Fi
Uses standard protocols to send/receive jobs:
SMB
IPP
Internet printing Protocol
LPD
Line Printer Daemon
Mail Server
sending/receiving mail in organization
Stores incoming mail, handles outgoing traffic and addressing
Critical service (like DNS) that requires 100% uptime, avail
Professionally managed and provided:
Local IT team
ISP
Cloud-based service
Problems usually detected quickly as everyone in org uses it
24/7 support staff
Connect to service immediately, remotely to diagnose & fix
Syslog
Standard for Message logging
All Services on network generate messages constantly
Admins receive or access these to monitor and troubleshoot
allows Admins to access all Messages in centralized database
Instead of manually accessing each service individually
Diverse systems, consolidated log
Syslog is very common protocol
Most devices with logging can send to Db via Syslog
SIEM
Security Information and Event Manager
Common in larger orgs for collecting all of the log files
Very large drive array for extended storage duration
Web Server
responding to browser requests from clients
Uses standard web protocols
HTTP/HTTPS
Build pages with specialized languages
HTML/HTML5
Pages downloaded to the browser
Static pages, simply transferred across
Dynamically created page on server, then sent down
Authentication Server
Login to authentication resources
Centralized management
U/Ps all kept in one service, for use by Other Services
E.g. in Enterprise, all access starts with initial login/VPN connection
Auth used across all services may be identical
Protects login data for many services we want to access
**uncommon on Home networks
not many shared services needed
A very critical resource
Always available
Network resources would be inaccessible w/o this
Redundancy
a set of servers providing this
Spam
Filtering out unsolicited messages
Email, Forums, etc.
Commercial ads, Malware, Phishing for info
Generally a folder already configured inside a Mail Client
Management can be complex
Identifying different types of messages
Handling & Storage once they’re identified
Security, space, duration (quarantining)
Mail / Spam Gateway
Screened Subnet
Some orgs have a separate mail gateway on their network
Firewall diverts Mail sent/received away from Internal Network
Can also be stored in the cloud, 3rd party-provided service
Either categorize as Spam / totally Reject access from org network
All-In-One Security appliance
Next generation firewall
or Older systems:
UTM
Unified Threat Management
aka “Web security gateway”
Many security functions
URL filtering
Content inspection
Malware inspection
Spam filter
CSU/DSU – connect to WAN
Router / Switch
Firewall
IDS/IPS – Intrusion Detection/Prevention
Bandwidth Shaper – quality of service devices
Real time prioritization of different application’s traffic
VPN endpoint
Encrypted tunnel for people outside the network to connect
Load Balancers
checks in with servers, drops unresponsive ones and shifts to others
Distribute client load across multiple servers on Enterprise networks
Invisible to end-users
Important for Large-scale implementations:
Web Server Farms
Database Farms
Fault Tolerance
Provide continuous uptime and availability of service
Server outages have no effect
Very fast convergence
Configurable load
Manage across servers, distributed load efficiently
Change the way protocols operate, since it’s sitting in the middle..
TCP offload
Maintain constant session
“Protocol overhead”
SSL offload
Encryption/Decryption happening on Load Balancer
Not managed directly by servers
Caching
Fast response
Requests don’t have to travel down to server
Common information already kept by Load Balancer
Prioritization
Advanced configurations of the traffic going thru
QoS for certain websites / applications
Content switching
Application -centric balancing
Direct some applications to some servers
Remaining traffic to other servers
Optimize comms for Best Responding Servers
Proxy Server
An intermediating server, sitting in the middle of conversation
Proxy receives client request, performs actual request to 3rd party
Examines response from server for safety
No malicious content
Sends response down to end user
Allows useful security controls to be built in
Access control – requiring U/P to access Web
Caching
URL filtering
Content scanning
SCADA / ICS
Supervisory Control and Data Acquisition System
aka ‘Industrial Control System’
Responsible for management and control of industrial equipment
e.g. Power Generation
Manufacturing
Allows real-time insight and mgmt of what's happening on devices
Very expensive systems
Machinery Outage would have a dramatic impact
Require extensive segmentation off of main network
No access from outside
Special rights, permissions, connections to gain access
Issues with Legacy and Embedded Systems
“really old” and/or entrenched technology supporting core functions
Legacy
Data Center problem with difficult services to remove once installed
Devices/Services that sit in the Data Center for 10+ years
Often a very important service is running on them, still works
Difficult to resolve any problem when soft/hardware difficult to replace
→ “Learning Old things can be just as important as learning
New Things”
Embedded
Purpose-built device
No access to operating system or other aspects inside device
Only access to the actual service/application it provides
E.g.
Alarm system, Door Security system, Time Card system
Commonly don’t have any OS we can update or view
Must rely on manuf to provide ongoing service/maint.
IoT Devices
Internet-of-Things
Now increasingly common on Home net, as well as Enterprise
Appliances
Refrigerators, Ovens
Smart Devices
Speakers, TV, Radio, Lights
Respond to voice commands
Climate Control
Device control of Air Control Systems, Thermostats, Fans, etc.
Access
Smart Doorbells, Door locks, garage Door Openers
Segmentation
Security is relatively critical
May require a segmented network for IoT devices
Protect access to our interconnected home services
INTERNET PROTOCOL & ADDRESSING
End-to-end support required to communicate in a given protocol
Devices on either end must have this address e.g. IPv4 / IPv6
IPv4
Primary protocol applicable to anything done on today’s internet
IPv6
Backbone of the internet Infrastructure
All major operating systems now support it
Will be using addresses for both
IPv4 Addresses
OSI Layer-3 address
4 sets of numbers separated by decimal – max value of 255
X.X.X.X
32 total bits in an Address
1 byte per block – sometimes called “8-bit segments”
192 . 168 . 1 . 131
=
11000000 . 10101000 . 00000001 . 10000011
…then realized internet’s popularity would exceed capacity of IPv4
approx. 4.3bn unique addresses possible (2^32)
IPv6 Addresses
Enough to assign IPv6 addresses to anything we might ever use
128-bit address length
340 unidecillion
~ 5 octillion addresses per living person
8 blocks x 2 bytes per block
%:%:%:%:%:%:%:%
Each block is 4 hex characters (4 bits per character) – 16 bits
Char:
8
f
5
2
Bit values: 0-15 0-15 0-15 0-15
(possible)
Binary
1000 1111 0101 0010
Numeric equivalent:
36690
Concatenate out all insignificant zeros
Use consecutive colons to alliterate a block of 0’s – 0000 (hex)
“Fe80 0000 0000 0000 5d18 0652 cffd 8f52”
>>> fe80::5d18:652:cffd:8f52
DNS Usage
Increased reliance on Names for referring to servers
Long and complicated IPv6 address too long to memorize
Subnet Mask
Prefixing – usually first 64-bits of IPv6 are the network address
(last 64 are the host address)
Manual Configuration
With IPv4…
Each device on network needs a unique IP address
1) Ensure there are no duplicates when assigning
2) Assign a subnet mask
E.g. 255.255.255.0
Bit masking to screen out the first 3 blocks of address
leaving only the Host address behind
Used by LOCAL device to determine which subnet IT is on
Subnet mask is NOT usually transmitted ACROSS network
Have to ASK someone what a network’s subnet mask is
Often provided both of these values at the same time for setup
If one of these parameters is missing, CANNOT assign IP
3) Assign a Default Gateway
for communicating OUTSIDE local subnet
IP address of the router
E.g. 192.168.1.1
These 3 are the bare minimum to assign IP to a local device
4) DNS is important so we don’t need to memorize website IPs
Our Router doesn’t know what these names mean
Only understands associated IP address
Domain Name Server does this for us
Typically configured in OS’s IP settings
E.g. 8.8.8.8 (Google DNS), 1.1.1.1 (Cloudflare)
List secondary DNS values because it’s a critical resource
Assignment of IP Addresses
We need automatic assignment of IP for an enterprise network
annually configuring would not scale well
BOOTP
Bootstrap protocol
released in Oct 1993
First to do automatic IP assignment
Didn’t assign all configuration settings needed
No way to detect device exiting the network / reuse address
DHCP
Dynamic Host Configuration protocol
released 1997
New version of BOOTP, renamed
Automatically configures…
IP address
Subnet mask
Default gateway
&more
Uses a 4-Step Process for assigning…
DORA - Discover - Offer - Request - Acknowledge
D – Discover
try to locate a DHCP server on local network
O – Offer
server offers IP to our device
R – Request
device will consider, pick one, and request back
A – Acknowledge
server provides all IP config settings needed
Ex: Setup w/ redundancy of DHCP
(Router relaying DHCP to “helper” server on a different subnet)
Discover – Client Workstation broadcasts to network on udp/67
Sent to all devices on local network
router + DHCP server on subnet
also received by outside DHCP server
Routers will not normally allow broadcasts to pass
But in this case it’s configured as “DHCP proxy”
a.k.a. “DHCP Relay” / “IP helper” (manuf. lingo)
Offer – both devices send offers back, broadcast on udp/68
Client workstation doesn’t have IP yet so broadcasts necessary
Request – client examines offers, sends broadcast on udp/67
contains formal request to take offer made by 1 of the servers
Acknowledgement – server broadcasts back on udp/68
confirms request
tells device to use Config settings in that initial offer
IP Address Pool
DHCP server initially configured with a RANGE of IPs for assigning
Dynamic
IP for a given device may change from previous days’
Static
Sometimes prefer some infrastructure to always have same IP
Could manually configure this by disabling DHCP
Must be created administratively / revisited manually
OR
IP Reservation
Done on DHCP server – associates IP by MAC address
APIPA
Automatic Private IP Addressing
a.k.a. “Link-Local” address
Cannot communicate outside local network
No forwarding by routers
169.254 – Last two ‘0-255’ address ranges reserved
(IETF standard)
Functional blocks
169.254.1.0 – 169.254.254.255
Devices randomly picks for itself within these ranges
ARP
Address Resolution Protocol
Device checks if other local machines using this address
Sent via ARP request
If no response received, address is assigned
E.g. “$ ipconfig -a” (Windows)
shows a DHCP server was unavailable
“Autoconfiguration IPv4 address: 169.254.[random] ”
+ “255.255.0.0” – default APIPA subnet mask
DNS Configuration
DNS is a service that converts fully qualified domain names
What we can type into a browser
Into something our Networks can use – IP
Not simply a standalone server providing this
Multiple servers across the internet
Working in a Hierarchy
Across all of the different fully qualified domain names
Distributed database
Many different DNS servers across the internet…
13 root server clusters
1000+ actual servers
gTLD
100s of generic top-level Domains
E.g. .com / .org / .net …
ccTLD
275+ country codes
E.g. .us / .ca / .uk …
E.g. DNS Hierarchy
“.”
→ “.com”
→ “.profmsr
end of the fully qualified domain name
TLD
main site
→ “www”
multiple servers.. Mail, [region], etc.
DNS Lookup
See visually how this translation operates…
dig
“$ dig www.professormesser.com” (command line)
Summary of information sent/received
“QUESTION:
www.profmsr.com. IN A
ANSWER:
www.profmsr.com.
www.profmsr.com.
www.profmsr.com.
300 IN A 104.22.72.108
300 IN A 172.67.41.114
300 IN A 104.22.73.108
…
SERVER: 9.9.9.9#53 (9.9.9.9)”
“A” – denotes type of request (address)
3 different IP addresses were returned
All associated with profmsr webserver
Redundancy – if one device goes down, another can handle req’s
nslookup
other systems that don’t support DiG
“$ nslookup profmsr.com”
Uses locally configured DNS server to provide associated IPs
*Non-authoritative answers
Resource Records
DNS records kept in a Database by DNS server
Used behind the scenes to keep fully qualified domain names, IP
addresses, details to help the translation
30+ types of records
e.g.
IP addresses
Certificates
Host alias names
Important, CRITICAL configurations
Settings must be CHECKED, BACKED UP, and TESTED
DNS Configuration File
Written in plain text – easy to modify with any editor
E.g.
Mail-exchanger records
(if more than one IP, will indicate prioritization)
List of machine addresses & fully qualified domain names (FQDNs)
Jack – a windows server
Mail – a Linux server (main)
Canonical (alias) names assigned inside the server
ftp
Chat
DNS Service Front End (Web-based)
Can just fill in settings on a form on a Config webpage
instead of need to understand records’ syntax / placement
Address Record (A) / (AAAA)
Defines the IP of a host
Most popular query
“A” or “Quad A” – denotes IPv4 vs. IPv6
A will have FQDN + associated 16 digit address
… + 128-bit hex address
Option of adding remarks (comments) on that line too
e.g. record (text file)
e.g. record (web-based)
TTL
Time to Live
Specifies how long an end user will remember this FQDN-IP match
e.g.
Device makes request to DNS server
stores / caches info for 15 minutes
Device removes info from cache after that
Needs server request to find site again
Mail Exchanger Record (MX)
where all emails should be delivered
Requires two separate records to work
1) MX
2) A – needed to obtain IP address for mail domain name
Text Records (TXT)
Storing text information for multiple uses (human-readable)
Useful public information
Originally designed for informal info
Specific uses today
Verification purposes
Changing config for domain
DNS servers are usually VERY secure
Requires adding a specific text block in DNS server
Human-to-Human Security feature
Verifies change made by an authorized person
e.g. administrator
Email security
Add info that helps verify origination of an email
View TXT records with DiG:
“$ dig profmsr.com txt”
…
QUESTION:
Profmsr.com. IN TXT
ANSWER:
Profmsr.com.
300 IN TXT
“stripe-verification=[key]”
…
TXT “v=spf1 include:mailgun.org ~all”
“Mailgun” – appendage for messages sent via their email service
View TXT records using nslookup:
“$ nslookup -type=txt google.com”
E.g. response includes…
TXT records for FB, Apple, Docusign, etc.
(domain name verification)
Sender Policy Framework (SPF)
List of all servers authorized to send emails as this domain name
Prevents mail spoofing by third-party servers
Mail servers perform CHECK
Did incoming mail actually come from Authorized host?
E.g. Mail Server receives email from “profmsr.com”
Queries profmsr.com DNS server
Reads SPF record in server’s TXT records
“v=spf1 include:mailgun.org ~all“
Determine if this really came from authorized host
E.g. creating an SPF record on DNS server Front End
Domain Keys Identified Mail (DKIM)
Digital signature assigned to outgoing mail
Takes email security one step further
Validated by mail servers as message traverses the network
Public Key associated with Digital Sig added to TXT record on DNS server
E.g. Configuration
text block – public key for ALL Digital Sigs sent from this domain
DMARC
Domain-based Message Authentication, Reporting, Conformance
What to do with messages IF Verification FAILS
Prevent unauthorized email use (spoofing)
Extension of the SPF and DKIM
Rules for what external (net) servers should do w/ INVALID emails
Policy is written into a DMARC TXT record
E.g. DMARC record on DNS server
“Accept all…”
“Send to Spam”
“Reject entirely”
Mail servers are tracking how many validate / fail behind the scenes
Compliance Report
Can query servers for report on these stats
How many messages got through via given SPF and DKIM config
E.g. DMARC record indicating:
WHAT to do with email messages
+ WHERE to send reports (in “Content” field)
DHCP Configuration
Server-side – What we’ll need inside….
IP address range
Subnet mask
Lease durations
Other…
DNS server settings
Default gateway
VOIP servers
DHCP Pools
Each subnet has its own scope (grouping of IP addresses)
E.g.
192.168.1.0/24
192.168.2.0/24
192.168.3.0/24
Server choosing from the pool for each IP assignment
Usually a large contiguous pool of IP addresses
DHCP server simply pulls any available addy in that range
BUT some situations call for exceptions, special rules in that scope..
Hold IP reservations
Exclude addy’s OUT of that range
E.g. “Scope” settings / properties
“Pool” – possible range
“Leases” – what have been previously assigned
“Reservations” – static device addys
“Options” – configure add’l parameters ( e.g. IP for VOIP Gateway)
E.g. SOHO DHCP server (Small or Home Office)
(unusual time unit … 86400 seconds = 24 hours)
DHCP address allocation systems
Dynamic
New devices – most receiving IP this way the first time
Could receive any addy in that range
Leased IP will change once time expires
Automatic
When DHCP servers also keeping track
Previously connected devices are kept in a list on server
Recent returning device addy’s will be held onto and
Reassign same IP to Device if still available
Reservation (Admin)
Manual configuration to hold IP for single device
Always receives same IP addy / others always excluded
Configured via Table of MAC addresses linked to IP addys
Media Access Control (MAC)
Every device has a unique MAC address
Burned-in address on the NIC
Static DHCP
a.k.a.
“Static [[ DHCP] / [Assignment ]]”
“IP Reservation”
E.g. MAC / IP table with associated Hostnames
Leasing
Dynamically assigned DHCP addy’s are always temporary
Device must check in again with DHCP server after a period
demonstrate that IP addy is still occupied
Otherwise– Lease times out, IP is up for grabs agan
Lease period is set in DHCP server config
E.g. 24 hrs
Reallocation processes
1)
Reboot and return to network
trigger automatic renewal of lease, same IP
2)
Device can manually release IP addy
a) When moving to different subnet
b) simply seeking a diff addy on same network
DHCP renewal
Check-in times scheduled according to Lease time clock
Main timer for Lease length is started upon configuration
Once that expires, addy is returned to DHCP server
T1 timer
Runs within the lease period
Checks in w DHCP server 50% way through lease
Device asks to keep addy for 1 add’l lease duration
Main timer resets to 100% of X duration – renewed
But server comms could be out during this check at T1
server may never return to network
T2 timer
Original DHCP server down, try rebinding to any DHCP server
Attempts this at 87.5% (7/8ths) of Lease time
Seeking to retain that original IP addy still
Redundant DHCP Server
E.g. ‘Lease stages – 8-day timer with a Redundant server’
post-T1 Renewal period exhausted, T2 kicks in
Process finally renews on 7th day
Redundant DHCP Server successfully contacted
New Lease on addy beginning again from day 1
VLAN & VPN
Local Area Networks (LAN)
Group of devices in the same broadcast domain
Reasons for separate domains / segments:
Security
Physical separation for stability/traffic
Capping network traffic
Functional divisions
But some inefficiencies exist:
Redundant, duplicate equipment across all areas
Duplicating the cost as a result
Connecting a few devices, but leaving a lot more ports empty
Switch’s interface capacity underutilized
Virtual Local Area Networks (VLAN)
Single switch, maintained by a single Power Source
+ Single Configuration
Logically associate various interfaces to certain networks
Switch itself provides the separation between each network
Devices then cannot contact “outside” networks
Virtualization groups the devices in their own Broadcast Domain
BUT using the same physical device providing functionality for all domains
Admin configures interfaces to segment as many networks as needed
More than 2..
Virtual Private Networks (VPN)
Combination of Software + Hardware
allows Secure data transfer over Public Network (e.g. internet)
Everything sent is automatically encrypted
No man-in-the-middle attacks feasible
From desktop/OS it appears like another known/linked private network
Underneath though, there is distributed external hardware involved…
Concentrator
Separate device we’re actually connecting to, somewhere
Standalone
Hardware device with specialized encryption hardware inside it
Integration
Added into existing Firewall / Multi-use device
E.g. VPN software running on a server
VPN implementations often have their own client software
installable on any computer
Most modern OS’s come with some VPN client by default
Can retain security even on Public / uncontrolled LANs (e.g. Coffee shop)
Internet connection itself may not be encrypted
Using VPN software that’s always on OR switches on encryption…
Encrypted Tunnel
Concentrator–Device link that exists virtually across intermediate net
Decryption/Encryption occurs on entering/exiting the tunnel
Traffic continues on Remote Network normally/unencrypted
E.g. Virtual Operation of outside Laptop on a Private Network
Encrypted Tunnel (red)
Virtualized over public hardware and infrastructure
Concentrator-Client side data en-/decryption
effectively Invisible to End User(s) on either network
INTERNET CONNECTIONS
Satellite Networking
Communicating to satellite in Near-Earth orbit
a.k.a “Non-terrestrial” communication method
High Cost – can be more expensive here due to launch vehicle
High Latency – due to long distance up and back down atmosphere
250 ms is typical
BUT Starlink advertising 40, and even working on 20 ms!!!
OK Throughput ~ 50 Mbit (down) / 3 Mbit (up)
Idea use case = remote areas, difficult-to-network sites
High Freqs ~ 2 Ghz
Obscured by optical barriers
Line-of-sight
“Rain fade” – can cause connection to drop
Fiber
Higher speed, Terrestrial type
Frequencies of light used instead of AC voltages
High information volume in shortest amount of time – GREAT for Internet
High Cost – equipment costs more than Copper, repairs expensive
Long Distance – much easier to maintain global comms
Very Common in corporate Enterprise Networks
WAN Core installations that are especially large, critical infrastructure
Supports super high data rates
SONET – Synchronous Optical Network
Based on original standards for parallelization
Shifted packet data into Frames, read via Frame Rates
Interleaved stream rates can “float” relative to overall traffic
Wavelength division multiplexing
Extends even further w/ overlapped signals on multiple freqs
Fiber slowly approaching actual end-use / private premises
Business and home use
Cable Broadband
Transmission across multiple freqs on single copper wire
Video, Voice, Data, etc.
Regional cable providers can provide data on “cable” network
DOCSIS
Data Over Cable Service Interface Specification
standard for comms on these networks
High Speeds ~ 50 to 1000+ Mbits is pervasive in America
Multiple Services, Same Infra ~ data, phone, tv all in one
DSL
Reuses existing copper Telephone Lines in the home
Asymmetric Digital Subscriber Line (ADSL)
The actual implementation found in most cases
Asymmetric – Download Speed faster than Upload
~ 200 Mbit down vs. 20 Mbit up
Limited by Distance – 10,000 foot from Central Office (CO)
Decreased speed with moving away
Faster speed as you are relatively close
Cellular Networks
Mobile Device’s cellular data connections
Tethering
Physically connecting to phone (USB) / Wirelessly (Bluetooth)
Use it as an internet Access Point for nearby devices
Hotspot
Use phone’s 802.11 Networking capabilities to create a LAN
Anything in range can connect to Wireless network and share Internet
Wireless Internet Service Provider (WISP)
Some areas where Wireless data companies service buildings
Public spaces – poor access or high need areas
Homes, typically in rural areas
Great for places where Infrastructure is insufficient or nonexistent
Outdoor Antennas
Often necessary to send/receive signal well on WISPs
Give VERY good performance – up to 1000 Mbit/s
May broadcast a 5G signal for home internet
Proprietary wireless ~ other types
Mesh Networks
WISPs often using “Meshed” 802.11 to build chained device grids
NETWORK TYPES
Local Area Network (LAN)
The term “Local” can be relative
But generally means in your building / group of nearby buildings
High Bandwidth – due to proximity and network technologies used
Ethernet
802.11 Wireless
Anything SLOWER than these isn’t considered on a LAN most likely
Wide Area Network (WAN)
Comms across cities, countries, continents
Slower than LAN typically – due to longer distances
Different WAN technologies for implementing:
Point-to-point Serial
MPLS
Other types of wide area technologies
May be Terrestrial or Non-terrestrial
Personal Area Network (PAN)
E.g. wireless earbuds
Bluetooth
Infrared (IR)
NFC
Applications:
Automobiles… audio playback, phone integration, navigation
Mobile phone… wireless headset
Health/fitness… sensor/watch data, workout telemetry, reports
Metropolitan Area Network (MAN)
Company with multiple locations in a city or geographic area
Connects all sites together over semi-long distances
Larger than a LAN
Smaller than a WAN
Historically MAN-specific topologies developed for this
Metro Ethernet
Given ethernet connection on both Ends
(I)SP lays the groundwork to link them
Commonly government owned – already have conduit ROWs (right of way)
Storage Area Network (SAN)
Centralized form of storage – extend local drives
High Speed – direct connection to a single Storage facility
Large Capacity storage systems on site
High Demand for Throughput
Block-level Access
Similar to access on local storage devices
Efficient Read/Writes over SAN
Must use isolated network / high speed network technologies
Wireless LAN (WLAN)
Communicating wirelessly in building
Short range – in highly localized area
Can add add’l access points to extend size
NETWORK TOOLS
Cable Crimpers
Specially designed to add connectors, similar to pliers
Versions for Coaxial, Twisted Pair, or Fiber Optic
Common to run RJ45 / Ethernet cables naked 1st, attach connectors 2nd
Twisted Pair Crimpers
pushes prongs through the insulating sheath, into copper
Contact Pins are initially slightly raised in the connector module
crimper lowers the sharp prongs into individual wires
Cable Stay that holds the insulation sheath in place at bottom
Best Practices
Good crimper
Good scissors / snips (electrician’s)
Good wire stripper
Use proper modular connector types for cable being used
E.g. Cat 5 vs. cat 6
Wi-Fi Analyzer
Listen to ALL signals on network, provide usage statistics
Which freqs in USE, which are OPEN
Wifi networks are incredibly easy to monitor
But must understand all frequencies in use over that network
Software (mobile device) or Purpose-built Hardware
Especially useful in high traffic areas – visualize points of interference
Also good for monitoring effects of physical changes, e.g. antennaes
Tone Generator
a.k.a “Tone Probe”
Allows easy location of a cable in congested environments
Two Components:
Generator
adds the analog sound to the wire
Inductive probe
just a speaker (doesn’t touch the copper)
Connects via:
Modular Jack
Alligator clips
Punch down connectors
Probe the other end of cable(s) and listen from cable-to-cable
Place against sheath of testing wire, not connector or copper
Lights up and/or emits Sound when positive signal detected
Punch Down Tool
For connecting wire to Punch Down Block instead of RJ45 ports
Wiring Blocks
Sizes: 66, 110, and others
Permanent connections
Each wire takes up its own spot on the block
Tool fastens them one-at-a-time
1) Pushes wire into the box AND
2) Cuts off excess wire, ensuring a good clean connection
Best Practices
Organization – Usually managing many different cables
Numbers – use to keep track of what’s connected to what
Twist – maintain the spiral as far as possible along length
Documentation – duplicate / match same numbers on both ends
Cable Tester
Performs basic diagnostics on internal wire functionality
Continuity test
Simple Wire Map
2 Units used together
Plugging into each end of cable
Output shows if Pin X connected to Pin X on both ends OR otherwise
Allows to see errors:
Missed Cables
Punched Down Incorrectly
Cross-Wires
Does NOT show:
Cross Talk values
Signal Loss
Those require more advanced tools
E.g. TDR
Time Domain Reflectometer
Loopback Plugs
Allows to test the interface, sending information IN/OUT serial port
Serial / RS-232
9-pin or 25-pin
Shows if Problem relates to cable vs. interface plugging into
Send/Receive values IMMEDIATELY within same device/interface
Other available versions:
Ethernet
T1 WAN
Fiber
These are NOT crossover cables
No multi-device connections
Reflexive
Taps and Port Mirrors
Intercepts network traffic
For Accessing and Seeing data going over the wire itself
Physical Taps
One way to see data on the wire
Disconnects link, placing tap in the middle
Copies all data
Sends to Packet Analyzer
Passive
Used on Fiber – doesn’t require power
Active
Used on Copper – requires power
Example Routing Schematic in a Tap
Port Mirror
Used in absence of physical taps
Contained in Switch functionality, Software-based
SPAN
“Switched Port Analyzer”
Takes data going between different interfaces on switch
Mirrors to a 3rd interface on the switch, connects to Analyzer
Resource limitations are involved in Switches generally
E.g. bandwidth on individual interfaces
BUT still a good temporary fix
NETWORK CABLES
Important to use the right cable for the job
Wireless still depends on Cables somewhere!
Often in NEW installations / setups you only get 1 Chance to Get it Right
Twisted Pair Copper Cabling
Balanced Pair operation
2 wires together with Equal & Opposite signals to one another
Transmit+ / TransmitReceive+ / Receive-
Twist
Signal is also twisting, moving away from interference
Positive and Negative signals compared to on another at terminus
Identify any Interference that may have impacted either
Different levels of Twist Rate
Interference will show variation across the pairs
Standards evolved minimum specs for multiple characteristics:
Ethernet Standard
Maximum Distance
Category 5
1000 BASE - T
100 m length
Category 5e (enhanced)
1000 BASE - T
100 m
*enhancement = addt’l validation testing was done
Category 6
10G BASE - T
55m (unshielded)
100 (shielded)
Category 6A (augmented)
10G BASE - T
100 m
Coaxial Copper Cabling
2+ Wires on Common- Axes
Wire conductor is 1 single conductor running the length
RG-6
used in TV or Digital Cable or High Speed Internet
Plenum-Rated Cable
No Plenum / Plenum duct vs open wall compartments in buildings
Addt’l reqs for network cable run through shared deadspaces (Plenum)
Special type of network cable Jacket
PVC jacket
Traditional jacket on RJ45 cable
FEP / Low-smoke PVC
Fire-rated cable jacket
Fluorinated Ethylene Polymer
Shielded Cable
UTP
Unshielded Twisted Pair
Most common
STP
Shielded Twisted Pair
More interference or add’l protection required
Shield around entire cable
AND/OR
Around individual conductor wires
Many have grounding wire too
Nomenclature
Writing on outside of wire jacket denotes type(s) of shielding
Syntax: [outer cable] “ / “ [inner pairs] “ TP “
U
Unshielded
S
Braided shielding
F
Foil shielding
e.g. F/UTP = foil around entire cable, no shielding inside
S/FTP = braided around outside, foil around inner wires
Direct Burial STP
Cable runs that are outside when ideally buried directly in the ground
Specially designed to be outside w/ waterproofing
Obviates need for a conduit to run inside of
Waterproof jacket
Repellent gel filling
Shielded Twisted Pair
Adds Grounding - help prevent any type of interference
“Draining” away any add’l voltages
Adds Rigidity - help strengthen the cable itself
Optical Fiber
Ethernet standards already exist for fiber optic
No RF signal makes it difficult to monitor or tap
Must physically intervene
Cannot “read” the signal inductively.. there is no EM field
Signal degradation is minimal - transmission over longer distances
Immune to RF interference
Best for manufacturing env’s
Fiber wire is very small (narrow) compared to copper cable
Actual fiber is a small dot inside of a protective ferrule
Light Source
E.g. LED
Sending light signal on one end of the tube to receiving equipment
Light
Bouncing through the fiber core without exiting or refracting
Core
Transmittent / Reflective material to allow unhindered travel
Cladding
Low Reflective Index
Absorbs and errant light that leaves core, not returned back in
Buffer
Coating that protects everything inside
Ferrule
usually a large Ceramic protector housing the fiber core
Multimode Fiber
Multi- and Single-mode — 2 broad categories of Fiber cable
Most common for Short-range communication (up to 2 km)
Each networking standard has specific distances for cable type
Low Cost Light Source is common, e.g. LEDs
Multiple Reflections (or “Modes”) inside result as incident light is “Large”
Single-mode Fiber
Long-range Communications
Up to 100 km w/o processing
Expensive light source is common, e.g. Laser
Much brighter, more focused light
Core is much narrower
Cabling Standard Structures
universal guidelines for twisted pair Markings & Installation
ISO/IEC 11801
(International)
Telecoms Industry Association - TIA
(U.S. and North America)
ANSI/TIA-568
Commercial Building Telecoms Cabling Standard
http://www.tiaonline.org
The Color Standards
Pin & Pair assignments for 8-conductor, 100 Ω, Balanced TP
2 Termination options for 8P8C connectors:
T568A
T568B
Application of either seems arbitrary but nevertheless must be consistent
Can NEVER terminate one side of cable with A, other with B
e.g ethernet “Crossover cable” (common misconception)
ACTUAL crossover cable covered in IEEE Standards (infra)
Horizontal Cabling
Most commonly associated with Standard A
Organizational End Users
Most commonly associated with Standard B
Zero physical / performance difference between the two!!
Pin Diagram:
A – Green grouped, Orange split | B – Orange grouped, Green split
E.g. Punch-Down Block for BOTH color schemes (alternate terminations)
- - - - - - HARDWARE - - - - - PERIPHERAL CABLES
Methods of connecting external inputs / devices to computer
Universal Serial Bus – USB
Simplifies connections
Printers, Storage devices, Keyboard, Mouse
USB 1.1
Low speed – 1.5 Mb/s, length < 3 m
Full speed – 12 Mb/s, length < 5 m
USB 2.0
480 Mb/s, < 5 m
USB 3.0
5 Gb/s, < 3 m (length not officially defined)
aka “SuperSpeed”
Connectors for Early USB
A plug
B plug
Mini-B
Micro-B
Higher Speed Connectors
changed with USB 3.0
3.0 A plug
similar to original
3.0 B plug
much different than earlier version)
3.0 Micro-B
VERY different
USB-C Connectors
addresses perceived problems of past implementations:
Many different connectors, changing over time
USB A wasn’t reversible, had a particular “up side”
Single Connector style to Replace all of these
NOT a change to signal transmission, cabling standards
e.g. different signals possible – video, data, Midi, etc
Smaller
Approximate size of Micro plug
Symmetrical
Can be plugged in upside or downside
Versions & Naming
These schemes are changing with each Standard upgrade
The standard itself doesn’t change
E.g. 3.0 – “SuperSpeed” – 5 Gb/s
(July 2013)
3.1
– USB 3.1 Gen 2 – “SuperSpeed+” – 10 Gb/s
… 3.0 becomes “USB 3.1 Gen 1”
(Sept 2017, introduction of USB-C.. extra Flip-flop wires)
3.2
– USB 3.2 Gen 1 x 2 –
… extra lane of comms
… 10 Gb/s using 2x “Gen 1” lanes
– USB 3.9⁸2 Gen 2 x 2 –
… 20 Gb/s using 2x “Gen 2” lanes
Thunderbolt
High speed serial connector
Data + Power on the same cable
Copper or Fiber connections
3 m vs. 60 m lengths
Daisy chain up to 6 devices together
e.g. 1 Tbolt interface –> 6 peripherals in series
V1
2 channel
10 Gb/s per channel
20 total
Mini DisplayPort connector
V2
20 Gb/s to any connected device using Aggregated channels
Mini DisplayPort connector
V3
USB-C connector implemented
40 Gb/s aggreg. throughput
Serial Console cables
Before there were universal serial buses…
25-pin and 9-pin connector types
DB-9
DB-25
RS-232
the Signal standard since 1969
Allowed Comms between computer and external devices
Modems, printers, mouse, networking etc.
Current usage:
Serial Console for Switch, Router, Firewall config
VIDEO CABLES
VGA
Video Graphics Array
a.k.a. DB-15 connector
Video-only
Need extra audio interface to do A/V
Analog
Signal attenuation after 5 - 10 m
Associated with blue color (via PC System Design Guide)
15-pin Connector type is unique to VGA
HDMI
High Definition Multimedia Interface
Digital
20+ m runs without signal attenuation
Video + Audio combined
19-pin (Type A) Connector type proprietary
DisplayPort
Older Digital standard
packetized signals … like ethernet, PCI express
Video + Audio
2 types of common connectors:
MiniDisplayPort
DisplayPort
Hooks that lock it into place on the interface
Release mechanism to remove
Passively compatible to HDMI & DVI
Crossover cable needed
DVI
Digital Visual Interface
Many types of interfaces in this class
Video-only
Single & Dual-link:
Single Link
3.7 Gb/s - HDTV at 60 fps
Dual Link
7.4 Gb/s - HDTV at 85 fps
Analog + Digital connections supported
DVI-A
Analog
DVI-D
Digital
DVI-I
Integrated
E.g. which type based on back of connector / interface
* Analog-capable must have full cross on the end, not a horizontal prong
* Single link has the middle array open / Double has entire prong array
SATA
Serial AT Attachment
Connecting storage devices INSIDE computer to motherboard
Power + Data separated on interface
15 pins Power
7 pins Data
Molex connector (power) may still be used with only SATA data
1-to-1 cables, end-to-end
No daisy-chaining, series connections
eSATA
External drives likely using eSATA (external SATA)
Matches speeds on standard revisions
Cable length higher - 2 m
Connector looks similar to internal SATA but it’s NOT
Larger
Different layout
Plugs into eSATA card/interface on back, not MB
SCSI
Small Computer Systems Interface
Standard for connecting peripherals
OG design for many connections
Single Interface
Daisy chaining up to 16 devices
Newer Implementions:
iSCSI
Virtualized (on networks)
Supports both types based on which format in use
PATA
Parallel connectivity
IDE
Integrated Drive Electronics
now just referred to as PATA
SATA
Serial connectivity
Advantages pre-SATA / USB
Scanners, CD, tape backups, external I/O
Daisy-chaining
Keep adding storage drives as you have open connectors
Narrow Bus
8 devices
Wide Bus
16 devices
Intelligent interface
Configuration funcitonality handled between devices
Industry longevity
Well supported in enterprise
Standard found in Virtual Systems now
Many types of Connectors
SCSI ID
Separate ID Number for each Device on cable
E.g. ID 0 = scsi controller, ID 2 = hard drive, ID 3 = cd-rom
Connectivity in a drive array
Single chassis with many different drives inside
Logical Unit - LUN
Further defined within SCSI ID system
Identify individual drives within a larger SCSI ID device (array)
SCSI Terminator
At end of physical bus
Internal to device OR a separate piece
Allows communication to all devices simultaneously
Serial Attached SCSI - SAS
Recent standard
Simplified over previous versions
No manual setting SCSI IDs
No jumpers, terminators, or settings
Why the Move From Parallel to Serial?
Increased Throughput
Similar to the move from IDE to SATA
Point-to-point connection
No more daisy chains
No more terminators, jumpers, etc.
Bus has two devices on it - controller + device
Control and Mgmt of SCSI + Modern speeds of serial
PATA / IDE
Parallel AT Attachment
‘AT’ - comes from original PC/AT computer by IBM
Common on Legacy Equipment circa 1999
Called ‘IDE’ before (Western Digital)
Speeds grew from 16 MB/s to 133 MB/s
CD-ROM devices
2 Devices per Motherboard connection:
40 Wire
original cable
Device 0 + Device 1
80 Wire
Device 1 + Device 0
Reduced crosstalk to increase speed
Same pins, double the wires
Connector has Notch + 1 missing pin to indicate orientation
ADAPTERS & CONVERTERS
Convert between different connectors w/ electronic compatibility
Convert between formats (e.g. USB to ethernet)
Usually a temporary workaround
E.g. DVI to HDMI
HDMI is electrically (backwards) compatible to DVI-D
No signal conversion is required
No loss of video quality
E.g. DVI to VGA
DVI-A backwards compatible with VGA
Only 640x480 supported
Analog-to-Analog
E.g. VGA to DVI-Digital
Not adaptable
Requires a Converter in the middle
E.g. USB to Ethernet
Newer laptops missing a RJ-45 network slot
Converter needed to translate USB <> Ethernet
E.g. USB-C to USB-A
Merge new standard with old, on peripherals
May need to combine on top of an Ethernet-USB-A adapter
E.g. USB Hub
Connect many peripheral devices with different aged tech
Memory expansion slots
Multi-USB gen / interface type
High speed connectivity
COPPER CONNECTORS
RJ – “Registered Jack” types…
RJ11 Connector
6 position, 2 conductor (6P2C)
Telephone, DSL
4 empty spaces for other wires
Some RJ11’s will have these additional positions filled
Interface for data uplink on DSL Modems
RJ45 Connector
8 position, 8 conductor
Ethernet
All positions filled
F-connector
Coaxial cable with threaded connector at the end
Cable television
analog
Cable Internet via modem
DOCSIS standard
Punchdown Block
Wire-to-wire patch panel
No intermediate interface required
Wires “punched” into the block permanently
Connector block cover clamped down on top of them
Permanent management of wires in your data center
USB 1.1 / 2.0 Connectors
USB 3.0 connectors
Introduces additional pins inside the traditional A & B sized connectors to
support higher speeds
USB-C
Double-sided, small and similar in size to OG usb micro-B plug
Used for more than just serial connections – Multi-Signal
Thunderbolt… Display Port… etc
Molex connector
4-pin peripheral power
+12V and +5V power variants for devices, storage, fans, other
Molex company
AMP Mate-N-Lok makes another version
Lightning connector
8-pin interface for Apple products
Power + Digital signal to iPhone, iPod, iPad devices
Competitor to micro-B…
Higher power output
Double-sided, no orientation required
DB-9
D-subminiature connector
Many console connections still use
Send RS-232 signals
Serial communications standards used for modem, printers, etc since 1969
Now in data centers using as Configuration port
Command line into your infrastructural devices:
Switches
Routers
FIBER CONNECTORS
Only so much real estate on a switch
Smaller connectors have the advantage
More interfaces possible
LC - Local Connector
Single interface
2 separate Fiber connections
1) Transmit
2) Receive
Can also be each used as separate strands of connection
Depends on standard and how many interfaces available on the switch
ST - Straight Tip
Naked Ferrule of the Fiber cable inserts
Quarter-turn locking “Bayonet” collar behind it
SC - Subscriber Connector aka ‘Square’
Looks similar to LC, but more squarish
Often combined in 1 connection
Can form separate runs as well
MEMORY
Typically in an operating system we’re looking at RAM requirements
Random Access Memory (RAM)
Slots
DIMM
Dual Inline Memory Module
Electric contacts are asymmetrical
64-bit data bandwidths
SO-DIMM
Small Outline DIMM
½ width of regular DIMM stick
Common in laptops
DRAM
Dynamic Random Access Memory
Dynamic
Needs constant refreshing from a power source
Without that, data disappears
Random
Any storage location can be accessed directly, unlike tape or discs
No rewinding, transporting, etc.
No clock
SDRAM
Synchronous
Clock regulates the flow of data in/out of the module
Some data is transferred each clock cycle
Standard timeframe
Queue up one process while waiting on another
Other components can anticipate exactly when this data will be sent
DDR
Double Data Rate
2X the number of data transmissions in a single clock cycle
Differing notch placement on the dual connector, preventing mismatch
Successive generations continued to double that….
DDR3
2X as fast as DDR2
16GB Max per DIMM
Not backwards compatible
DDR4
Even faster frequencies
64GB Max per DIMM
Not backwards compatible
DDR5
Fastest transfers between module and motherboard
Not backwards compatible
MEMORY TECHNOLOGIES
Virtual Memory
aka Virtual RAM, Swap File
Swap out some RAM-held data to Physical Memory - hard drive or SSD
Area, size of HD for virtual memory is Configurable via OS/Software
Can be automatically managed by system as well
Slower than actual RAM
Temporarily storing until we find more room in normal memory
Multi-Channel Memory
Can greatly increase throughput in system
Dual, Triple, Quad-channel…
Spreads the load on a single module across multiple memory modules
Ideally the same memory module types are kept in each slot (channel)
Color-coded Slots
E.g. Show you which slots to use for multi-channel
Error Checking
Some environments allow memory to Check Itself…
Used on critical computer systems
VM servers, Database servers, any server
Parity Memory
Adds a parity bit to all information stored in RAM
Won't always detect an error
Also cannot connect an error when found
Error Correcting Code (ECC)
Detects errors and corrects on the fly
Not all systems use ECC
Looks the same as non-ECC memory
Parity
‘Even’ Parity
Used by many memory modules
Added to create an even numbers of 1’s in that data
= ‘1’ where preceding bits are odd
= ‘0’ where already even
Has memory been corrupted? (a bit turned off or on)
Obviously not reliable if more than 1 bit changed
STORAGE DEVICES
Hard Disk Drives - HDD
Non-Volatile
Magnetic storage retains data even when powered off
Rapidly rotating platters
Random-access
Retrieve data from any part of the drive at any time
Moving parts
Spinning platters, moving actuator arm
Limit access speed
Possibility of breaking
All HD’s will eventually fail, the question is “WHEN”
E.g. Platter speed and access speed
Higher rotational speed = faster read/write intervals
Multiple Platters, Multiple Heads reading
Stacked
Allow reading from any conceivable corner of the disk
Sizes
3.5” -- desktops
2.5” – common in both
M.2 – newer laptops
Solid-State Drivers - SSD
Non-volatile
Memory not dependent on power
Durability
No moving parts anywhere
More durable and less prone to mechanical failure
Performance
Much high speed
No spinning platter delays
Interface
Crucial to the increased performance of SSDs
E.g. 2.5” SATA
Makes these drives interchangeable on any system with this interface
Portability
Smaller components inside of SSD allow overall device smaller
mSATA
mini-SATA (short-lived transitional move from 2.5”)
Allows shrinking the SATA drive into smaller devices
Same data, new form factor
Actually allows several different form factors
Not common on new devices today as m.2 came out
m.2
Smaller form factor than regular SATA
Single connection to Motherboard
Pulls power directly from socket
No SATA data or power cables
Also connects directly to PCI Express bus (PCIe x4 interface)
Allows even higher throughput, 4 GB/s or faster
Different connector types
“Keys” in interface pin-types have names…
B – M – B/M (both)
Doesn’t guarantee you are getting better than SATA speeds though
M.2 interface may still be using AHCI
Check Mobo documentation to see if it will use NVMe
Mobo may also support only one M.2 Key Type, B or M
Controllers
AHCI (SATA)
Advanced Host Controller Interface
Originally used by SATA for hard disks
Moves data off disk into system memory
SATA rev3 reached its upper limit of 600 MB/s
SSDs needed a faster comms framework
NVMe (M.2)
Non-volatile Memory Express
Designed to match needed throughput of SSD tech
Lower latency
Higher throughput
Ditched SATA interface
Introduced M.2 instead…
Installation
Find M.2 slot on Mobo
Slide SSD in & fasten to board on opposite end via screw
Flash Drives
Flash memory… aka EEPROM
Electrically Erasable Programmable Read-Only Memory
Non-volatile
Write Limits
Their is a lifetime cap on number of times you can modify
Unlimited Reads
Still readable
Not designed for archival storage
Easy to lose or damage
Always have a backup!!
Example Formats
USB Flash Drive
Secure Digital - SD
MiniSD
MicroSD
CompactFlash - CF
xD Picture Card
Optical Drive
Small bumps (pits or colors) read with a laser beam
Microscopic binary storage
Relatively slow
Popular for archival media
Especially for ROM - Read only
Formats
CD-ROM
DVD-ROM
Blu-Ray
Available as Internal drives available for Desktop & Laptop
Or as External, USB
RAID
Redundant Array of Independent Disks
aka ‘Inexpensive’ disks
An array of drives used for efficient storage & redundancy
RAID is a NOT a Solution for Backup, it is for…
Availability
Uptime
HD failures common in storage facilities due to 2 factors:
Huge amounts of data - multiple TB
Lots of spinning, moving parts
Not a COPY of your data (need a secondary Backup method for that)
It is Actively Read/Written data that is in use
RAID Levels
Different types of RAID
Some do NOT provide Redundancy
Raid 0 (Striping)
2 drives - Single set of data split into blocks
Everything split evenly between the two
+ Performance increase
- No protection against loss …. RAID Zero = Zero Redundancy
RAID 1 (Mirroring)
2 drives - Duplicated set of data, on separate disks
Mirrored perfectly between the two
+ Protected against loss of either disk
- High disk utilization
- 2X the drive space required
RAID 5 (Striping w/ Parity)
Similar to Raid 0 but with Protection
Data set split into blocks across multiple drives
Additional Parity block added to each set of data
Requires 3+ disks
At least one drive’s worth of space for Parity
Can distribute Parity blocks across all drives
Helps with Recovery Process
+ More efficient than Raid 1, No Duplication
+ Single drive loss doesn’t ruin the data
+ Can rebuild lost Data in Real-Time using Parity block
- Recalculating may cause a Performance degradation
But RAID controller / CPU may handle this with minimal impacts
RAID 10 (Stripe of Mirrors)
aka “1 + 0” ….Best of Both Worlds
Data Set striped across drives (RAID 0)
Redundancy via a paired mirror copy of each drive’s data (RAID 1)
+
+
+
-
Can afford to lose a drive in each stack.. Up to a 50% outage
Performance equal to RAID 0
Redundancy equal to RAID 1
Requires the most number of disks
MOTHERBOARDS
Fundamental physical component in all of our computers
CPU
Memory Slots
Power Connectivity
Expansion Slots
Every function begins and ends with the motherboard
Same basic layouts, with differences due to size and scale
Power connections are fairly standard
Need for future expansion
Airflow - becoming increasingly important for performance
40+ possible types categorized
ONLY 2 or 3 are Popular
Relatively compatible between different PC cases
Vary based on features and how much room needed onboard
Desktop
More room for MB
Form Factor Devices
Smallest of MBs
Choosing the Right Form Factor
Consider the task, CPU, card requirements, etc.
E.g. Media center
Video editing
Thin client
ATX vs. ITX Families
Standard-ATX
‘Advanced Technology eXtended’
Standardized by Intel in 1995
Most commonly found in Desktop
Versatile -lots of peripherals, expansion slots, memory
Updates have been mostly to power source and quality
e.g.
20 pin connector
24 pin connector, additional 4/8 pin connector
Add’l CPU power for more voltage
Mini-ITX
Created by VIA Technologies in 2001
Screw-compatible with ATX
Fits almost any enclosure
Suited more for a single purpose machine
E.g. Home/TV console, streaming
Expansion Slots
Computer Buses
Lay out the Communication Paths on the motherboard
Connectivity need additional functionality
Modular / Independent components on the motherboard
Traces moving along the silicon from part to part
Conventional PCI
‘Peripheral Component Interconnect’
Created in 1994
More common on legacy devices
Different Bus sizes
32-bit
64-bit
Parallel Communication
E.g. Multiple expansion slots sharing a single path
I/O Controller Hub
Central logic communicating to all devices on PCI bus
E.g. 32-bit PCI bus
Different Voltages
3.3V key
5V key
Slots are in specific spots so only correct card can be installed on that MB
PCI Express
PCIe replaces older standard
Can take up varying real estate on board
Different Pin & Key styles vs. PCI
Additional Hook that locks card into slot
Serial Lanes
NOT a parallel connection
Unidirectional
+ Slower devices don’t slow everything else down
More Lanes are added to support More Devices / Data
Full Duplex…
X1
“One by”
x2
X4
X8
X16
x32
E.g. “By Four” PCIe
24-Pin Motherboard Power
Standard connector size now for MBs
Original was 20-pin
Add’l 4 introduced for PCIe
New connector still works a 20-pin MB
Pins are keyed though so orientation is always correct
Some have notches, others are squared off
Plastic Clip lock that fastens onto MB power slot
Provides 3.3 (DC), +/- 5 (AC) +/- 12 (AC) volts
4-Pin ATX Power
+12V (DC) for older ATX MBs, usually for CPU power
Keyed Pins so can only be plugged in a specific way
Possible Labels:
ATX12V / P4 / CPU
Storage Drive Interfaces
SATA connectors
eSATA connector
External SATA - link to more storage drives outside computer
Can be built-in on MB or an Expansion Card
Same throughput / performance as an INTERNAL SATA
Headers
“Pin header”
Simple electrical interface for attaching a connector
Different functions…
Power Fans
USB
Button connections to Case exterior
Header Labels:
AAFP
External Audio connectors on case
Other Audio functions
USB
Possibly for legacy USB connection
USB 3.0
TPM
Trusted Platform Module
FAN
Power and Control of cooling fans
RESET Switch
Hard Drive Light
Power Light
M.2 Connector
Plug in to SSDs
Only on newer MBs
Motherboard Compatibility
What type of chip.. Intel or AMD? (Determines mobo)
Subtle differences between manufacturers
AMD cost / Intel performance
Locked in to a Mobo once this is decided
Different sockets
CPU Socket
Cover lifts up to expose socket
Replace chip and bring cover back down
Lock in place
Server Mobos
Multiple CPU sockets
Splits the load
Extra memory slots
up to 4+ modules
Expansion slots
More space and different sizes
Overall size
Larger ATX
Rack-mount System
E.g. newer Server mobo w/ 2 CPU, 6 Memory slots
Desktop Mobos
Range from
Full-size
Compact
Monitor-Only
1 CPU
Memory from 2 - 4
Expansion slots likely more limited
E.g. PC motherboard w/ 1 CPU, 2 Memory slots
Mobile Mobos
Laptop’s requirements taken into consideration
Small and Light
CPU Limited in Speed
Designed for Power Usage & Efficiency
Thermal throttling varies performance
Limited options for Modification
Fixed memory, CPU, functional capabilities
Few if any add-ons possible
Portability
Smaller devices
Low power consumption, long endurance
System boards are proprietary
Ad hoc build
Tailored specifically to device shape and dimensions
Replacement isn’t easy – exact OEM part needed
Integrated modules
Most functional components soldered onto system board
Failure of one component means whole Mobo replacement
BIOS
‘Basic Input/Output System’
aka ‘Firmware’
System BIOS, ROM BIOS
The screen we see on startup
Stored in ROM or flash memory
Less likely ROM today
Flash is dominant
Power On
Initializes CPU and Memory
Begins executing code of the BIOS
POST
Power-On Self-Test
Not comprehensive HW Diagnostics
Simply seeing if basic are in place
CPU, Memory, Video, Input (keyboard/mouse)
Then looks for configured Boot Drive…
Boot Loader
Installed on Boot Drive
Starts OS
E.g. 1 or more BIOS configs stored in Flash Memory (main + backups)
Legacy BIOS
Had been around for 25+ years
Text-based
Interaction between OS and HW happened through this layer
Could not access hardware directly
Limited Hardware support
Some config changes to supported functionality
But NO upgrades or changes to these capabilities
No add’l Drivers for
…Network Interfaces
…Video
…Storage Devices
No new portions of BIOS itself
UEFI BIOS
‘Unified Extensible Firmware Interface’
Based on Intel’s EFI
Standard that can be implemented by multiple Manufacturers
Same features and capabilities
Replaces a legacy BIOS
For modern computers
E.g. Modern UEFI BIOS on an HP – Advanced capabilities
Ability to add drivers from the BIOS for new Devices, Storage, etc.
BIOS Settings
Accessing
System Setup must be triggered during Launch sequence at Start Up
Secret Buttons
Del
F1, F2
Ctrl-S, Ctrl-Alt-S
Once pressed, given access to BIOS
Hyper-V (Windows)
Virtualization software can also provide access
Changes to Virtual BIOS instead of actual one
VMWare Workstation Player
NOT available on VirtualBox though…
Virtual BIOS Simulators (online)
‘UEFI Bios simulator’
Offline bios emulation
Fast Startup (Windows 8/10/11)
No button press to enter ‘BIOS settings’ at Startup
Turned on by default
Cannot get into BIOS
Windows isn’t completely shut down on power down
Hibernates
Wakes back up from previous session
Bypassing is possible though…
Secret Hard Button Press
Hold Down ‘SHIFT’ while pressing Restart
Forced Restart
Settings > Sec > Recovery > Adv Startup > Restart Now
System Configuration
‘msconfig’ in command line
Boot Load Interruption
Interrupt normal boot 3X in a row
Disables Fast Startup process
Presents the normal Boot Options screen
Backups
Possible to make changes that cause boot failures / prevent startup
Always create backup for working BIOS settings prior to modifications:
Downloadable Copy
Written Notes
Snap a Pic
Modifications
Don’t make changes unless you are certain of setting and what it does
Revert to Previous Backup if it doesn’t work!
Boot Options
BIOS will know what to do when Power On
Enable/Disable HW Devices
Make visible to OS or not
Boot Order
Prioritize Devices to Boot from
E.g.
Bootable USB Drive
SSD
Hard disk
CD-ROM
E.g. Different Boot Sequences in Lenovo BIOS
USB Interface / Permissions
Enable/Disable USB connections
Special Security challenge
Very small storage devices
Very large capacities
Convenient
High speeds
U.S. DoD disabled all Flash media b/c of a USB Worm in 2008
USB Setup
BIOS Settings > Devices >
Fans
Processing power generates heat
Many different fans running
E.g.
CPU
Chassis
Memory
Etc
Integrated Fan Controller
Onboard temp sensors and chip on Mobo
Mobo increases/decreases airflow per performance
Configuration
BIOS Setting > ‘Intelligent Cooling’ (Lenovo)
Performance vs. Fan Noise level
Secure Boot
Included in UEFI specification
Protecting BIOS before OS even loads
Make sure system can’t be corrupted by Malware
Malicious Software
Drivers or OS software that can “OWN” your system
Digital Signatures
Cryptographically secure
Used by BIOS to verify Boot Process authenticity
NO Third-Party modifications
If abnormalities found?
Stop Boot Process
Limit scope of that malware
Support in many OS’s – Linux, Windows
UEFI Secure Boot
Additional standard BIOS features…
OS Public Key
Manuf’s key must be known to BIOS beforehand
Digital Signature checked again during BIOS Updates
Prevents unauthorized writes to this data in Flash Memory
Bootloader Trusted Certificate
Uses Key to check Digital Signature for the OS’s bootloader
Without this it must approve Digital signature manually
Boot PW Management
Limit who can Start computer
Limit who can make changes to BIOS
System won’t start unless PW provided to gain access
Requires resetting BIOS entirely if you forget/lose it!
BIOS / User PW
Start system / OS
Supervisor PW
Change BIOS
Config/enable devices
Etc
‘CMOS’ / BIOS config
‘Complementary Metal-Oxide Semiconductor’
Backed up with a lithium battery usually
Legacy type of module where BIOS config was stored
Still referred to often as the BIOS config
Flash Memory
Where everything is stored nowadays on Mobo
Cannot access thru the system when locked out
Must reset physically…
Jumper Reset
Push down the bipole jumper onto 2 pins to short them
Power on system
BIOS config resets
CMOS Battery Reset
Old school way of doing it
Maintained older BIOS configurations
Nowadays only maintains Date/Time settings when off grid
Trusted Platform Module (TPM)
Additional HW supported by the Mobo
A specification for encryption functions
Especially important for Full Disk Encryption
Cryptographic Processor
Generally will perform cryptographic operations
E.g. random number gen, key gen
Persistent Memory
Certain Keys can be burned into TPM and never changed from Mobo
Verify existing keys on system
Versatile Memory
Digitally sign new data, Send, & Verify origin from 3rd party
PW Protected
Cannot hack into TPM from outside
Brute forces, etc.
All TPM features can be config’d in BIOS Settings
Hardware Security Module (HSM)
Solution for LOTS of Crypto keys and processing required..
E.g. Large enterprise environments…
Clusters
Redundant Power
High Performance cryptographic hardware
Standalone, Purpose-Built Appliance
Plug-In Adapter Card
Key Backup for All Servers in secure environment
All keys stored on HSM, and no one has direct access
Lightweight HSMS for Personal Keys on the go
May also Offload CPU overhead from other devices:
Cryptographic Accelerator
CPU
‘Central Processing Unit’
OS technologies for running a CPU….
Architectures
Actual maximum support value of processing is less than that, per OS
32-bit
aka ‘x86’ (old Intel design)
2^32 … 4 GB of information can be stored
64-bit
aka ‘x64’
2^64 … 17 billion GB can be stored in processor
Backwards compatible with 32-bit applications
ARM
‘Advanced RISC Machine’
Chip designed by Arm Ltd., licensed out to others
Extremely efficient and fast in processing
Less power required
Less heat generated
Simplified instruction set
Mobile / IoT (traditionally)
Now there is M1 / Apple Silicon
Lines between x64 and ARM OS’s are starting to blur
Software / Driver Compatibility
Must match architecture / OS version being used
Installed in “\Program Files” or “\Program Files\x86”
Processor Cores
CPU = Not actually a unified monolithic device
Main processing on the core, which can be many
Dual Core
Quad Core
Multi-Core
Caches
Each Core can have multiple of these
Speed processing of information in/out of the CPU
Dedicated Caches
Shared Caches
E.g. CPU Die - Actual Circuitry & Diagram
Tend to have their own Memory Controllers & Graphics Processors built-in
Multithreading
Different processes occuring between seemingly 2 different CPUs (to OS)
Hyper-Threading Technology (HTT)
Single CPU core acting like multicore
REAL performance isn’t a full 2x though
15-30% boost in throughput of processing
OS Support required - must be written for HTT
All moderns OS’s support it
Virtualization Support
Virtualize additional OSs while operating other instances or different OS
Sharing the same physical components
VERY resource intensive
Took this functionality out of software and put in HW, on CPU
Intel Virtualization Technology (VT)
AMD Virtualization (AMD-V)
May require enabling in BIOS
Check to ensure proper settings are being used to optimize this
EXPANSION CARDS
Extending the standard functionality of computer through more HW
Default Mobo may not provide everything needed at all times
User-friendly install process
Relatively simple
Hardware itself
Sometimes Drivers too
Selecting the correct slot
Lining up the keys, pins
Sound Card
Output
High end audio
Advanced headphone amplifier
Home theater / Dolby processing
Multiple inputs
Music recording interface
Podcasting
Microphone
Interfaces
3.5mm Headphone stereo
RCA L/R
Line In stereo
SPDIF
Video Card
Most CPUs provide basic video processing now onboard
Nothing extra required for basic operations
Discrete Graphics Card
Different than integrated
Separate
Higher Performance
Gaming and Video Editing applications
Interfaces
VGA
DVI
DisplayPort
HDMI
Capture Card
Video as input, not output
Live streaming, External Camera control, etc.
High performance, with high bandwidths/resolutions
Interfaces
HDMI
SDI
Serial Digital Interface
Coaxial cable-based
Network Interface Card (NIC)
Ethernet usually integrated now
Some applications call for more interfaces
Or Nonfunctional onboard ethernet
Common on specialty devices
Serveres
Routers
Security Devices
Multi-port Ethernet
Single card, up to 4 connections possible
Documentation
Must check Mobo compatibility, available slots, specifications
Don’t buy and install Expansion Card until you’re sure it’s the right one
Minimum Reqs
Hardware, Software
Knowledge Base
Know issues, or “Gotchas” that would deny support
Support Forums
What have other people said, found to work?
Driver Installation
Some allow you to go straight into physical install…
Plug-n-Play
May need to occur BEFORE inserting the Card
May be included IN the OS by default
Always need to update latest versions either way
Necessary to uninstall previous Driver Versions 1st
Setup/installer/files will be Manufacturer provided
Manual installation through Windows Device Manager
COOLING
Common way to provide airflow through components
Case Fans
Pull cool air in, push warm air OUT through back of system
Critical factors
Mobo Layout
Component Location
Devices
Wiring
Power
Fan Size & Style
Also must consider volume level
On-Board Fans
Designed to cool an entire adapter card e.g. video card
Bulky, taking up additional case space
Must not bump into other adjacent expansion card real estate
Fan Specifications
Standard Sizes
80mm
120mm
200mm
Different Speeds
Variable speed
Noise Levels
Not all sound same
May replace a quieter fan w same speed as another
Passive / Fanless
No fans at all - NOISELESS
Device contains no onboard cooling systems
Likely contains some type of heat sink
Common Applications:
Very small systems
Space limited
Use-case limited – e.g. Sound, Video playback
Video Servers
TV head unit
Satellite receiver
Media Server
Heat Sink
Dissipates heat through Thermal Conduction as cooler air passes by
Metal – typically Aluminum or Copper alloy
Fins/Grid w High Surface area
Thermal Paste
Aka ‘Thermal grease’ or ‘Conductive grease’
Bonding agent used to maximize thermal transfer
Complete contact, spreads heat out evenly
Only a little bit is required
Pea-sized amount is good for a CPU
Reusable - still good even if Sink has been removed
Thermal Pad
If thermal paste is too messy
Almost as effective but an okay replacement usually
Solid pad
Cut exactly to the size needed at installation
Downside = Must be replaced each time Heat Sink is removed
Fans can be combined with Heat Sinks to drive cool air directly through it
Larger applications with Tall Heat Sinks stacks and many fins
Liquid Cooling
Coolant circulated through a computer
Higher-end systems
E.g. Gaming
Graphics work
Overclocked
Liquid Heat Exchanger / CPU Block
Has a liquid inlet / outlet
Flat conductive surface attaches to CPU, etc.
Coolant Radiator & Fan
Cools returning liquid using a radiator on exterior of case
POWER SUPPLY
/*
!ALWAYS DISCONNECT FROM POWER SOURCE WHEN SERVICING!
!SOME DEVICES STORE POWER IN CAPACITORS - DISCHARGE 1st!
!NEVER CONNECT TO THE GROUND OF AN ELECTRICAL SYSTEM! */
AC power is coming in from power sources
Computers use DC Voltage - this must be transformed in power supply
Converts AC (120 or 240) to
3.3 V DC
5 V DC
12 V DC
Most important component to establish functionality
Nothing else will work if this doesn’t
Amperage (A)
Flow of electrons past a point / unit of time
i.e. the diameter of a hose
Larger = greater flow
Voltage (V)
Electrical “pressure” that’s pushing the electrons through
i.e. how open the faucet is upstream
Wattage (W)
Measurement of Real Power use in a system
Volts * Amps = Watts
E.g. 120 V * 0.5 A = 60 W
Current
Different Types of Power received / sent
Alternating Current - AC
Long Distance
Direction of the current constantly reverses
Distributes electricity efficiently over long cable
Frequency
Timing of that reversal cycle is important
60 Hz (USA / Canada, 110 to 120V)
50 Hz (Europe, 220-240V)
Direct Current - DC
Current moves in one direction only
Dual-Voltage Inputs
Voltage varies by country
Don’t plug a 120V PSU into a 230V Power Source!!!
Manually switching between 120 and 230 V
Requires a meter
Auto-Switching Power Supply
Power Supply Outlets
Different DC Voltages required for different components
Positive vs. Negative
Voltage is the difference in the electrical potential
Where you measure from determines the potential
Electrical Ground is the common reference point
i.e. Basement is -10 feet from your front door
2nd Floor is +10 feet from your front door
+12 V
PCIe adapters
Hard drive motors
Cooling Fans
Other modern components
+5V
Legacy MOBO components
Many now using +3.3V however
+3.3V
M.2 slots
RAM slots
MoBO Logic Circuits
+5 VSB (Stand-By)
Standby voltage needed when in hibernate mode
Routinely checks to see if you’re pushing Power Button back on
-12V
Integrated LAN
Serial Ports (older)
PCI cards (some)
-5V
Mostly legacy Mobos
ISA adapter cards
Uncommon on modern mobos
E.g. Modern PC Power Supply specifications
24-Pin Mobo Power Connector
Main motherboard power input with various input voltages
Provides +3.3, +/- 5V, +/- 12V
4 newer pins added to power PCIe - originally 20 in legacy ATX
24-pin supply is backwards compatible with older Mobos
There will just be an overhand
E.g. Keyed connector for proper orientation
Redundancy
2+ PSUs
Internal to a server
Each can handle 100% of the load
Would normally both run at 50% - distribute evenly
Hot-Swappable
Replace a faulty power supply without powering down
Connectors
Fixed Connectors
Trunk of cables hard-wired in
May have too many or not enough
Mobo + all other components
Would have to replace entire PSU if run out of connectors
Modular
Able to add cables as needed
Fewer Leftover wires
Better Airflow
Slightly more expensive
Size
PSUs are rated by Watts
Overall + Individual output voltages
Optimal to balance Maximum Power <> Actual Needed
Bigger isn't necessarily better - Also more Expensive
Does not speed up your computer
Physical Dimensions ARE very standardized
Any manuf’s model should fit in your computer case
Proprietary Systems MAY be unique / nonconforming though
Sizing a PSU
Calculate Wattage required for All components in system
E.g. CPU, storage devices, video cards, etc.
Video Cards
High-End Video Processors are usually the largest power draw
Card Specs may recommend a particular PSU wattage
50% Rule-of-Thumb
50% Actual-to-Max capacity is a good approximation
Efficiency + room to Grow
- - - - - - PRINTERS - - - - - MULTIFUNCTION DEVICE (MFD)
Office Equipment performing various functions as:
Printer
Scanner
Fax
Network connection
Phone line connection
Print from Web
Many moving parts = Lots of ways for it to go wrong!
Spatial & Location requirements
These are critical because of its Size & Use Case
Need to be in centrally accessible area to many people?
Power
Network
Accessibility
Large devices – unbox them in a suitable area that can fit it
Not obstructing any walkways
Printer Drivers
Need drivers on OS in order to perform each and all functions it provides
OS version
Windows 10 vs. 11
Architecture version
32 vs. 64
You can’t mix and match drivers - they must be exact
Each printer will be specific to one of these 2 languages & driver:
Printer Command Language (PCL)
Created by HP for their laser printers
Used throughout industry
PostScript
Created by Adobe
Purposed for High-End printers
Now found in use for many types of printers
Wired Device Sharing
Allows others to physically connect to & print to this shared device
USB Type B
Most common connector used
Type B on the Printer → Type A on the computer
Ethernet
RJ45 connector
Printing over the network, no USB connectivity/physical proximity
Bluetooth
Limited range
Nearby devices
802.11 Infrastructure mode
Same network connecting devices via a WAP
‘Infra Mode’ indicates everyone in the area has access
802.11 Ad hoc mode
No access point
Direct link from client device to printer
Sharing the Printer
Providing network access
Create a Printer Share (e.g. in Windows)
1) Physically connect printer to a Computer
2) Computer mediates printer access from other computers
Cons: When that computer is turned off, Everyone loses access to that
computer
Create a Print Server
Print directly to the printer
Jobs are queued on printer itself
Jobs are managed on the printer
Web-based front end (managed on server side)
Client utility (managed remotely on computer)
Configuration Settings
Duplex
Double-sized printing
Not ALL printers have this!
Requires no manually flipping over or feeding pages
Orientation
Portrait vs. Landscape
Portrait
Paper doesn’t rotate
Landscape
Printer compensates for 90-deg transpose
Tray Settings
Printers may have more than 1 paper source
E.g.
Plain paper
Letterhead
Etc.
Choose the specific tray in the printer dialog
Properties of trays may be seen in Device Settings
Admin configures and adds notes on tray contents
Quality
Only printing a Draft? Use lower quality setting
Resolution
E.g. 600 x 600 (DPI)
No Color - Greyscale
E.g. Color = White
Color-Saving
E.g. True Color (24 bpp)
Printer Security
Toner is expensive – restrict access to minimize use
User Authentication
E.g.
Everyone
Set rights and permissions
Printing Vs. Management Rights
Badging
Authenticate via Company I.D. when approaching printer
Releases print job - quick and easy
Audit Logs
See who printed, how much, and what type
Benefits:
Cost management
Security monitoring
May reside in Windows Event Viewer / System Events
May be built into printer itself
Secured Prints
Printer must support this functionality and have it enabled
E.g.
Windows PIN-Protected Printing
Define a passcode to release job
Input PIN to printer console to print and retrieve
Flatbed Scanner
Allows to read page and save in digital file
Different Form Factors:
All-in-1 Multifunction Device
Standalone Flatbed
Large stack can be loaded and scanned 1 by 1
Automated Document Feeder - ADF
Network Scan Services
Can decide what happens to that scanned image
Scan to Email
Scans can be sent to your email inbox
Careful because large scans can fill up your mailbox!
Scan to Folder
May be on Windows file server
Server Message Block - SMB
Or on a centralized server
Microsoft Share
Scan to Cloud
Upload to cloud storage account
E.g.
Google Drive
Dropbox
Etc.
LASER PRINTERS
Complex Process combining:
Lasers
High voltage
Charged ions
Powdered ink
Heat
Paper
Very High Quality
Fast printing speeds
Imaging Drum
Image drawn onto imaging drum – “painted” with a laser
Photosensitive drum
Takes image, picks up some toner, and presses that negative
Toner transferred from Drum to the paper using heat
Replacement
Separate component
Replaceable normally
Combined w/ Toner Cartridge
Requires replacing BOTH when 1 is finished
Easy to access / remove / replace in EITHER case
Fuser Assembly
Toner rolled onto page from drum STILL needs to be affixed permanently
Fuser uses Heat + Pressure to melt the toner
E.g. Brown cylinder of Fuser assembly with Hooks that fasten it On/Off
Easily Replaceable too
Transfer Belt and Roller
(Color Laser Printers)
CYMB toners in 4 cartridges
Cyan
Yellow
Magenta
Black
Transferred from Cartridge to Belt
Transferred from Belt to Transfer Roller
E.g Transfer Belt
Pickup Rollers
Must pick up paper from Printer Tray
Rollers grab a single page
Possible Malfunctions:
No pages found
Multiple pages coming out together
Needs periodic cleaning OR replacement
8I
E.g. Pickup Rollers with Crisp, New rubber grooves on the pads
Separation Pad
Works in conjunction w/ Rollers to ensure just 1 page is pulled
Duplexing Assembly
Double-sided printing
Occurs inside the printer w/o manual flipping
Two-Step process
1) Prints side A
2) Turn page over
3) Prints side B
Additional Hardware to allow this flipping
Included mechanism
Shipped with printer
Add-on
Must be bought, installed separately
E.g. one type of Duplex flipping mechanism
Printing Process
1. Processing
Data sent down to Printer
Nothing moving in the printer YET
Once print job rendered in memory…
2. Charging
Corona Wire or Charge Roller imparts Negative Charge to drum
Clears the drum, preparing for image
3. Exposing
Laser creates discrete Positive Charges along the drum
4. Developing
Toner in cartridge is also Negatively Charged
Will stick to those Drum sections exposed to the laser
5. Transferring
Drum rolls toner onto the Paper as it passes through Printer
6. Fusing
Affixing Toner to the paper permanently using heat & pressure
Toner melted on - paper will be warm to the touch!
7. Cleaning
Removes excess toner from drum
** Drum may complete several full turns just to complete 1 page **
Cleaning, exposing, transferring, repeat
LASER PRINTER MAINTENANCE
Drum & Cartridge Replacement are common tasks
Low Toner Messages - not 100% out yet but will be unable to function soon
Toner can also contain the OPC drum
Organic PhotoConductor drum
** YOU SHOULDN’T BE SEEING THIS – COVER PROTECTS IT **
1). Sensitive to Light, so must remain bagged until immediately before use
2.) Power down printer 1st
3.) Remove packing materials from cartridge
4.) Replace
Variations
Side-installing
Drop-in from top
Maintenance Kit for Laser Printers
Manufacturer supplied (by request)
Would contain all parts commonly in need of replacing in maintenance
Mechanical and Heat stress wears them out
E.g.
Feed rollers
Fuser unit
Other worn parts
Manuf. should recommend a Maintenance Cycle length
Usually based on # Pages printed
Global Page Counter
Used to indicate when routine servicing needed
Must be RESET when maintenance has been completed
** FUSER UNITS ARE HOT – power off & allow cooling period **
Laser Printer Calibration
Different toner cartridges print with different densities
Variation in bright/darkness may be noticeable
Process can be automatic or manual - check Printer documentation
Cleaning
Laser Printers are dirty – toner + dust from papers
Check Manuf’s recommendations for cleaning Inside & Outside
Best Practices
H20
Isopropyl Alcohol (IPA)
No harsh chemicals
Outside – damp cloth
Inside – Wipe dust first , never use regular vacuum!
LaserPrinter vacuum
Specific for sucking up toner
Clean off stray toner with cold water, as hot water bonds it
Rollers – Clean rollers with H20 and IPA
INKJET PRINTERS
aka ‘Ink Dispersion’ printers
Color & High Resolution output
Cartridges very Expensive
Proprietary – only available from Manuf.
Ink type tends to fade rapidly over time
Not a good media for Archive purposes
Ink type tends to clog easily
Requires daily cleaning cycle inside machine
Ink Cartridges
Places drops of ink onto a page
CMYK – Cyan, Magenta, Yellow, Key (black)
Integrated Print Heads
Some cartridges include more than just ink
Allows you to replace header at same time as ink refill
Others separate the ink cart from heads
Feed Rollers
Pick up and feed paper
Must be clean and not worn out
Easily pull sheets through printer
Duplexing
Both-sided printing w/ automatic page flipping internally
Carriage and Belt
Cartridges pulled along on a Carriage back and forth across page
Carriage MAY contain its own Print Head
Belt pulls entire belt assembly
E.g. Brown belt pulling carriage across paper
Printer Calibration
Align nozzles to the paper
Resulting lines should be crisp
Colors should align
E.g. Calibrated – benchmark lines and color blocks are all flush, square
INKJET PRINTER MAINTENANCE
Keeping ink heads unclogged is highest priority
Malfunction Signs
Output having streaks or sections of missing color
Manual Remedy
Cleaning process can be triggered automatically by button
Can also take each cartridge out and physically clean heads by hand
Replacing Inkjet Cartridges
Easy, straightforward process
4 Colors
SOME Multi carts combine ink colors
If any 1 of these runs out, entire cart must be replaced
1) Open clip on top
2) Remove and Replace
3) Printer auto runs align and cleaning process
Recycle the empty cartridges!
Inkjet Printer Calibration
Align nozzles to paper
Lines should be crisp
Colors shouldn't overlap
Print test sheets and make minor adjustments as needed
Clearing Paper Jams
Lots of twists and turns over rollers
1) Remove paper tray first, any loose paper
2) Try too remove paper from path
a) Apply firm pressure, not ripping
3) Check for scraps left behind
a) Remove all loose paper
THERMAL PRINTERS
Feeds specially coated white paper with treatment, Heats portions
Turn black on those portions
No Ink!
Very quiet
Paper is very heat sensitive
Fades out to black in sun
Also clear tape adhesive will turn those portions white
NOT suitable for archiving
Use Cases
Cash Registers
Credit Card Terminals
Quiet areas
Feed Assembly
Pulls paper through printer
Long cylinder that holds paper in place with friction
Gears on the side turn that cylinder
Heating Element
Full-length
Metal, often silver component
No moving print head
Paper moves by it
Different parts of it heat up
Thermal Paper
Paper covered in chemical
Thermochromic Paper / Thermal paper
Color changes when heated
Feels different, even if it looks normal
THERMAL PRINTER MAINTENANCE
Replacing Paper
Relatively Inexpensive
Sizes differ quite a lot – keep Note of the exact size it takes
Not like laser paper
Actual Replacement quick and easy
Simple paper feed
Small device – can do with one hand in many cases!!
Cleaning Heating Element
Sometimes marks show on the output, or just messy output
Liquid cleaner is sufficient for getting the heating cylinder working clean
IPA
Get a cleaning pen
Follow Manuf’s recommendations
Swab the element gently only on the area where it makes contact
Cleaning Cards
Cleans the head AND paper pathways
Passes through as a blank
Removing Debris
Relatively smaller amount of dust
Paper bits only
Blow out with compressed air
Do this OUTSIDE
Wipe out with Damp Cloth
Do Not Use Vacuum
Static electricity created by moving dust – bad for electronics
Avoiding Hot Areas
Paper will turn if you store it improperly
Also the printer itself must be operated in a suitable area
IMPACT PRINTERS
Dot-Matrix Printer
Print head with small matrix of pins
Presses against a ribbon to make a mark on printer
Entirely by force of compression
Each Dot impressed on paper makes up the type output
Good for Carbon / Multiple copies
Presses through multiple sheets at the same time
Relatively lower Cost-per-Page
Requires only the ink inside ribbon
Drawback is the Noise of the Impactor
Typically louder than any other Printers
Drawback is also the Resolution not as good
Bad for graphics
Great for simple letters and numbers
E.g. Print Head w/ Heat Sink on ribbon along paper edge
Print Head component is relatively large – needs to dissipate HEAT
Heat Sink
E.g. Print head, relatively small
Entire Row of Pins are about the width of a single character
Requires lots travel to cover printed width of paper
Printer Ribbon
A piece of Fabric
Absorbent
Single unit, never ending circle – cycles through as it goes by head
Ink inside ribbon moves onto page
Easy to replace
Proprietary Sizes
Specific printer types based on Manuf. so must check
Tractor Feed
Continuous Paper Feed
Perforated Edged Paper
Used to pull paper along the printer
Folded in zig-zag stack, neverending length
Greenbar paper
Same as normal perforated but with ledger lines
Used for mainframe printing
Will work in ANY Dot-Matrix printer
11” high x 14” wide
Allows better control than using friction
Feeding Process
1) Tractor feet lift up to receive paper in place
2) Line feet perfectly level across
3) Lock guide feet in place onto paper
3D PRINTERS
“Print” in three dimensions
Use an Electronic Model to generate output
Additive Manufacturing
Creating layers upon layers to build up the final output
Not like machining - subtractive process
Rapid prototyping ability
Build on screen & Create IRL to see immediately
Deploys anywhere around the world
Useable in space to fabricate parts for critical purposes
Beam up the model from ground control and print on site
Types of 3D printing:
Filament printing
Fused Deposition Modeling (FDM)
Melt filament to print 3D objects in very fine layers
Print a layer -> Move up a bit -> Print another layer
Good all-around printer
Larger print bed than Resin printers
Filament material easy to manage
Minimal mess
Few disposal issues - long strands of hard filament
E.g. Filament threaded into machine for melting applicator
Resin Printing
Liquid resin
Stereolithography (SLA)
Smooth and detailed fine objects
Hardened using a Light Source
UV light / Laser
Melted Resin in bottom of reservoir
Work dipped down into it
Light focuses at exact points to harden new layer along working edge of
object
Build platform moves up, shakes off excess resin
Repeats
Challenge is managing Liquid Resin
Requires protective gear
Disposal needs Hazmat facilities
Print Bed
Large work surface used as 3D object is built
Flat, usually adhesive on top (filament) or bottom (resin)
Clean
Level
Stable
Sticky material used to make this possible
Many different print bed options
Large
Compact
Etc.
Resin printers often have a smaller print bed than Filament
- - - CLOUD / VIRTUAL - - CLOUD MODELS
Cloud Computing
Advantages:
Performance
Distributed
Service-based
Deployment Models
Private
Virtualize local data center
Public
AWS, Azure, GCP etc
Hybrid
Some on site, some public infra, data centers
Community
Cost sharing
Comparison of Cloud Models
Cloud Characteristics
Shared Resources
Internal Cloud
No shared resources
Build your own
Paid up front
No ongoing expense per use
External Cloud
Share resources
Underlying infra is 3rd party owned
Cost is metered per use or Tiered (up front)
All Pay as You Go
Metered Cloud services
Cost to store, upload, and download
Non-Metered
Pay for blocks of storage
No variable costs to upload/download
Rapid Elasticity
Can increase/decrease instances as needed
Instant Resource Provisioning
Scale up and Down seamlessly
High Avalability
System uptime is constant
Redundancy allows this
File Synchronization
Information can be duplicated across locations
INternational
Infrastructure as a Service (IaaS)
aka ‘Hardware as a Service’ (HaaS)
Outsourced equipment
You supply the code / software you want to run on it
Internal Mgmt and Security
Better Control of Data
E.g.
Web server providers - old school Hosting
Software-as-a-Service (SaaS)
On-demand Software
No local installation
Outsourced mgmt of data and apps
Less Control of Data
End-to-End application offerings - No Dev work required
E.g.
Google Mail
Microsoft 365
Platform-as-a-Service (PaaS)
Middle ground between the other 2
No Servers, No software
Someone else is providing the building blocks you need to build it
Modules, Dev Environment, etc
E.g. INventory
Login
Check Out
Integration and Security of components also provided by PaaS provider
Deskstop-As-a-Service - DaaS
Basic application usage provided virtually
Apps running on a remote server
Virtual Desktop Infrastructure (VDI)
Minimal OS on the client – low resource, small footprint
High Network Connectivity (dependency)
Requires lots of data since it all happens across the wire
E.g.
Amazon Workspaces
Looks like a Windows platform on the screen
CLIENT-SIDE VIRTUALIZATION
One COmputer, many OS’s
Each OS believes it has its own resources but they are shared
Host-based virtualization
Main Desktop + others virtualized within
Standalone server
Hosted VMs
Enterprise level
Been around since the IBM mainframes in 1960s
Legacy Software on Newer OS
Needed for running different APP versions on the same computer
OS-Specific Application/Release
Cross-Platform Virtualization
If you just need different OS’s simultaneously
Each of their strengths, without compromising
Move between OS desktops seamlessly through the GUI
No rebooting required
Saves time and resources – though it may SLOW down your computer
Hypervisor
Virtual Machine Manager
Manage virtual platform and Guest OS’s
May require a CPU specifically supporting Virtualization
Hardware Virtualization (built-in)
Acceleration capabilities specific to a CPU
Hardware Mgmt
System resources can be done on virtual system
Processor Support
Intel Virtualization Technology (VT)
AMD-V
Memory
Extra beyond normal host OS requirements
Disk Space
Each virtualized OS gets its own disk image
Network
Config on each guest OS
Standalone
NAT
Bridged
Virtual Switch
Sandboxing
Isolated testing environment
Disconnected from Real World production env
Copies of Production resources are used
Virtualize Dev process
Break code here
Additional Dev features
Snapshots and versioning with backups
Rollback features
Building the App
Develop Environment
- secure
Dev sandboxed testing
Test Environment
- secure also
Test in production mirror
Never touches production
Hypervisor Security
Security between VMs is a question
No major vulnerabilities yet
VM escaping
Malware recognizes its on a VM
Gains access to Host machine - Hypervisor compromised
Jumps across multiple guest OSs
E.g.
Hosted Services are often Virtual environments
Segregrates customer data
Guest OS Security
Each guests is self-contained
Requires same procedures and measures
Use traditional controls
Host based Firewall
ANti-Virus Spyware
Monitor potential Rogue Machines
Rogue VMs
Black hats create their own Guest on your system
No visibility into what they're using you for
Network Requirements
Most client side VM managers have their own virtual internal networks
Different ways to configure:
Shared Network Address
VM shares a single IP address with physical machine
Uses a private IP internally
Uses NAT to convert to the Physical host IP
Network Address Translation (NAT)
Bridged Network Address
VM is on a network itself, each one
Goes through network config process same as a Device would
Other networked devices can access it regularly too
Hypervisor doesn’t need Translating
Private Address
No connection out - Locked down VM
No network address received
Only within Virtual network used by other VMs on that machine
Network of VMs (Internal only)
- - - TROUBLESHOOTING - - TROUBLESHOOTING PROCESS
Change management processes offer guidelines for system upgrades
Change Control
Formal corporate policy w/ defined procedures
Goal is to avoid downtime, confusion, mistakes
No Changes w/o Process
Plan for the change
Estimation of associated risk
Have recovery plan B
Test parts of that before making actual chage
Document above, submit for approval to Change board
Schedule and make the change
…Similar process for troubleshooting, ad hoc…
E.g. Process
Identify the Problem
Information gathering
Get as many details as possible
Duplicate the issue if possible
Identify symptoms
Possibly more than one?
Question the users
They’re your BEST sources of details
Compare Records
Determine if anything has changed
Who was in the wiring closet?
Approach multiple problems separately
Break down into smaller pieces treating each symptom as its own
Backup Everything
Youre going to be making some changes
Rollback Plan
Revert to a previous configuration
What else has Changed?
Users may not be aware of
Eg.
Environmental changes
Infrastructural changes
Sources of Clues
OS Log files
Applications may have their own logs
Establish a Theory
Start with Obvious Causes first
Occam’s razor
E.g. is the ethernet cable plugged in?
Is the power cord all the way in the wall?
Consider Everything
Unusual causes also are common
Out-of-the-Box Thinking
List All Possible Causes
Prioritizing obvious causes at the top
Easy Theories
Least difficult to test
Root Cause Analysis
Research the symptoms
See what other people know about similar issues
Resources:
Internal knowledgebase
Google searches
Test the Theory
Confirm each Theory
Determine next steps to resolve the problem if so
Theories didnt Work?
Reassess or ..
Escalate
Third-party / expert may have better perspective
Create a Plan of Action
Implementing the troubleshooting step in the actual Production
environment
Build the Plan
Incorporate changes + Revert back coverage
Correct the issue with a minimum impact
Refer to vendor instructions
KnowledgeBase and support articles
Documentation and manuals
Identify Potential Effects
Every plan can go bad
Have a Plan B
And a Plan C
Implement the Solution
Execute the plan
Fix the Issue
Implement during the specified timeframe that was approved
Change Control Window
May have limited resources - need pull additional help
Third-Party support
Roll out multiple changes simultaneously
Verify Full System Functionality
Once fix is implemented we have no idea the intended effect was reached
Test must be part of your plan
Have customer confirm the test
Acceptance Criteria
Predefined tests set with the users ahead of the fix
If environment is still working + Problem resolved = PASS
Implement preventative measures
Ways to avoid this issue in the future
Document Findings
Document everything we did
1) To confirm the changes decisively
2) To build the knowledgebase and make it repeatable
Documentation
What were original symptoms?
What action did you take?
Explain results after implementing
Helpdesk / Knowledgebase Software
Platform common in enterprise environments for storing this info
Allows everyone in the org access to the troubleshooting docs
TROUBLESHOOTING COMMON HARDWARE
PROBLEMS
Power On Self Test - POST
Tests Major system components before bootup of OS
Main systems (CPU, CMOS, etc)
Video
Memory
Failures usualled indicated via Beeps or Codes flashed
Bios versions differ on this – check documentation
No use in memorizing beep codes
Know WHAT TO DO when you hear SOME
Consult Motherboard Documentation
Blank Screen
Listen for beeps
Bad video, bad RAM, no CPU or fault in CPU
Bad BIOS configuration
BIOS time and date setting
Prompt: Incorrect or Reset time & date
Basic function of the BIOS to keep track of these
Maintained w/ Mobo battery
Solution: Replace the Battery
Attempt to Boot from incorrect Device
Boot order may need reconfiguring
Start BIOS config and fix Boot order
Confirm startup device has valid OS
USB drive may also be superceding other drives
Windows Stop Error – Bluescreen of Death (BSOD)
Provides information on why this paericular error occurred
Stop Code
Can lookup on Windows.com
Must restart still in order to get OS running
Windows Event Viewer
Once successfully back up you can see error dump associated
Useful when visiting user who has this but doesnt copy details
Third Party Support
Microsoft support pages don’t offer so much help, Stop Codes neither
Contact components manufacturer instead
They may be able to use your Debug logs and collected further info
Reasons for Startup/Shutdown BSOD
Bad hardware, bad drivers, bad application
Use previous environment that was working if you find a culprit
Last Known Good Configuration
System Restore
Rollback Driver
Also try rebooting in another mode for debugging
Safe Mode
This helps narrow down as not all drivers are loaded here
Repeat or Remove Physical hardware changes
Reseat the board, connections etc
Run hardware diagnostics of the system if possible:
Hardware Diagnostics Utility
UEFI Bios diagnostics (built-in)
Spinning Ball of Death (Mac OS especially)
“Loading” cursor indicator stalls and shows an infinite system wait
i.e. the Hourglass on old-school Windows
Requiring Shutdown / restart to recover from
Possible Reasons are Many
Application Bug
Bad hardware
Slow paging to/from disk – virtual memory
Restart computer
Solution: consult Console logs to determine cause
Black Screen
Check power and signal cables all around:
Monitor plugs
Easy, Most common
Input Selection
Options for which interface the monitor will see as INput
E.g.
HDMI
DVI
VGA
It needs to know which one is in use
Case: Image is also Dim
Check brightness controls
Brightness controls
Swap Out Monitors
Isolating the problem to the peripherals or the computer itself
Goes Black once Windows loads
Try different startup option
VGA Mode (F8)
Works across every monitor on market
Will indicate if its the driver
No Power
Cutoff at the source (outlet)
Multimeter - AC
See if there’s voltage coming out
Cutoff at the power supply
Look at cables
Check all switches
Multimeter - DC
Receiving clean power from PSU?
Check components for signs of power
Motherboard or Case fans?
If both are out, it’s in the PSU
Bad Motherboard
If mobo connected fans dont work + no POST
What problems does it identify
Fans spinning
Case fans have lower voltage requirements
PSU may only be outputting minimal voltage
Not enough to power whole Mobo
Sluggish Performance
Look at activity IRT
Task Manager
Check for high CPU utilization and I/O (raed writes)
Look at each individual process
Performance (tab)
Data on all system processes
If all processes look low utilization, search deeper
Updates? Background processes?
Disk Space
Check for available disk space and defrag
Defragmentation
For hard drives
Power-Saving Mode (unplugged Laptop)
Many will auto- power down into low performance on Battery
CPU Throttling
Also when its running hot
Temperature Rises
May have additional fan noise which indicates this
Anti-virus / Malware
May increase overhead when scanning or inspecting files in background
Overheating
Every system component contributes to heat
CPUS
Video adapters
Memory
Cooling Systems
These need to be working and clean to properly work
Fans & Airflow
Heatsinks
Temp Sensors
Temp Monitoring Software
Built-in with BIOS
HWMonitor
Dust covering vents, expansion slots
Smoke and Burning Smell
Electrical problems – the smoke makes everything work
Always disconnect power
There should never be a burning odor
Locate bad components
Visual inspection
See where on Mobo something may have failed
Replace individual component or whole Mobo?
Intermittent Shutdown
No Warning, Black screen and total shutoff
Check log details!!
Check Windows Event Viewer
Excessive Heat
Automatic shutdown to protect components?
High CPU, graphics activity, gaming
Check cooling
BIOS status of fans
Failing Hardware
Has anything changed?
Single component causing system to shut down
Device Manager
See info on components, errors
Run diagnostics too and see if OS can isolate malfunctioning
Begin removing anything that could be bad
Trial-and-Error
Application Crashes
May provide error message:
Window may disappear from screen without warning
Event Log
Check for immediate details on the app crash
Also historical data for app / system performance
Reliability Monitor (Windows)
Additional utility that separates:
1) App failures
2) Windows failures
3) Other issues
Timeline view of utilization and errors from Event Viewer
Solution: Uninstall Program and Reinstall Latest Version
Grinding Noises
Computers should only ever hum or buzz lightly
No abrupt noises!
Rattling
Loose Components
Was an adapter card not screwed correctly?
Heatsink coming unglued?
Scraping
Hard drive failing
May lose data soon if not backed up!
Clicking
Fan blockages
Oscillating sounds are a telltale sign to dislodge material
Pop
Blown Capacitor
Check Mobo carefully for bulging, split, or exploded wide open ones
E.g. One good capacitor (right) One bulging (left)
Solution: Replacement of the capacitors
+ Check other components on Mobo for Spilloverdamage from this
Freezing / Lockups
System completely stops
Frozen mouse
FROZEN screen
No error messages
Check for other indicators / activity
Hard drive
Status lights
Hard keys – CTRL ALT DEL, ALT ESC, ALT F4
BIOS Beeps
Keyboard Lights – Capslock, etc.
Recent system changes - Drivers? Patches?
Check recency – Uninstall and see what happens
Low Resources
RAM, Disk storage
Hardware Diagnostics
This is the last resort if the above aren’t working
Continuous Reboots
Observe Extent of the Boot Process
Important to record how far the startup process gets when it stopped:
BIOS only
OS Splash screen
Previous Boot Configurations
Bad driver?
Boot from last known working config (F8)
Remove any recent changes made prior to issue
Safe Mode (F8)
Loads a limited subset of drivers
Successful bootup here in Safe Mode?
System Properties (Config)
Disable “Automatically Restart” option
When STOP error or BSOD occurs you have time
And you can..
Detail and Document everything on Freeze Screen
Bad Hardware
Remove adapter card, swap some memory (last resorts)
Inaccurate System Date/Time
Bad motherboard battery
Often a button style Li battery
Replace CMOS battery
Manually Resetting Date/Time continuously
Bad battery will require this repeatedly on reboot
Bios Reset
Removing and changing battery doesn’t do this anymore
Bios settings in Flash memory on Mobo
Jumper the Mobo and Restart
TROUBLESHOOTING STORAGE DEVICES
Storage Failure Symptoms
Read/Write failure message
“Cannot read from the source disk”
Slow Performance - Still Working
Constant LED Access activity
Retry.. retry.. Retry over and over to read
Loud Clicking Noise
Click of Death
Also any grinding, scraping
Drive is failing or already failed
Responding to Disk Failures
Get a Backup immediately
Check for loose / damaged cables
Check for overheating
Especially if problems occurring after startup
Check PSU
Especilly if extra devices have been added, drawing on it heavily
Not enough voltage
Must remove Hardware or Upgrade PSU
Run hard drive diagnostics
Use those from drive / computer manufacturer
Use a know good computer to test the drive
Boot Failure Symptoms
“Drive not recognized” “Boot device not found”
Lights Showing access / No Lights
CMOS beeps
Detailed Error messages
Operating System not Found
Drive is there and showing but boot volume / OS isn’t
Responding to Boot Failures
Check cables
It could be a physical problem
Check boot sequence in BIOS
Check for removable disks - USB
Check for disabled storage interfaces
These might prevent access to boot volume
New Installation? Check hardware physical config
Data cable / Power cable
Try different SATA interfaces on Mobo
Try the drive in a different computer
Data Loss/Corruption
Hard drives = mechanical devices
They will always fail
Repairs difficult and expensive 3rd party data recovery company
Still some data may be unrecoverable
Dust-free env required
SSD stops working
Full failure - read/write
Reading still, but cannot write any longer
Could CORRUPT data if you continue using it
Data Loss Solution = Backups
ALWAYS HAVE A BACKUP
RAID Not Found
Data center, server storage
Multiple drives connected, not just one
Missing or Faulty RAID Controller
RAID Disk Stops Working
Each RAID is different – a single drive could be failing
Replace or update that drive in the system
RAID Manager
Can give you a status of each drive in array
Model Type …. Performance data
Failures / Errors will be noted in the status
RAID Recovery
Don’t start pulling drives until you check the console
S.M.A.R.T.
In-built diagnostics capabilities inside drive itself
Accessible though 3rd Party utilities / Drive Manuf.
Self-Monitoring Analysis & Reporting Technology
Write times… spin up time… Seek error rates.. Etc
Avoiding Failures in the first Place
Number of errors will start building up if there’s a problem with drive
Tie to Automatic Data Monitoring / Alerts from System
Schedule Disk checks
Many Raid arrays will perform their own checks periodically
Warning signs
Backup immediately and replace ASAP
Extended Read/Write times
Performance issues in storage that can affect total system wait times
Complex System interactions
A lot is going on, many dependent components – possible delays, lags
Memory access
Cross bus communication
Spinning drive access
Writing / reading data to different types of storage devices
Delays can occur anywhere along the way
Standard Measure of Storage Device Access / Performance
Input/Output Operations per Second (IOPS)
Very broad metric but comparable across all devices / systems
Useful in comparison
E.g.
HDD = 200 IOPS
SSD <= 1 million IOPS
Usually higher on the Read side, slower on Write
Missing drives in OS
OS boots normally
Other expected drives not shown
Check BIOS – especially if drive is physically present
Internal drive solutions
Loose or missing cables
Reseat the m.2 drive on Mobo
Replace drive because it has failed
External drive solutions
No power to the drive or bad connection
CHeck proper USB interface is being used
Network shares
Missed connection at Startup?
Reconnect at sign-in
Connect with Login script (run again)
TROUBLESHOOTING VIDEO AND DISPLAY ISSUES
No Video Image / No signal
Cable?
Check both Power & Signal cable
Multiple inputs?
HDMI, DVI, VGA
Switch through different Input interfaces
Image is Dim
Check Brightness / Contrast controls first
Hard buttons on monitor
Swap the Monitor out to another System
Try it out on another computer that is known to be good
Failed Monitor
If it doesnt work on another system
No Video after Windows loads
Start in VGA mode (F8)
Go into this during the Windows startup process
Image Quality problems
Almost still workable.. but
Flickering color patterns incorrect etc
Check the cable itself + Pins on connector (VGA)
Missing Colors are an extra clue to that
If any has been damaged, replace/fix
Distorted image and geometry
Check OS settings
Refresh rate & Resolution compatible?
Need to match display specs
Check and replace cable if nothing comes up
Disable hardware acceleration
Troubleshoot with the software drivers
Native Resolution
An LCD display is fixed
Blocky letters / bleeding in output
Muust use matching Display settings for that pixel configuration
Best picture = matching Native Res
Aspect Ratio must at last match
This is the alternative to perfectly matching the pixel’s dimensions
E.g. 2560 x 1600 ~ 1920 x 1200
Burn-In
A problem across all onitor types
Image was kept on screen for too long
Ghost image is left behind
Pixel-Shift
A feature on some displays that will alter an image held up long
Not noticeable
Image Sticking
Commonly referred to on LCDs
Remove by displaying white screen for extended period of time
This will unstick it
Dead Pixels
Always black – a manufacturing defect
Can’t be resolved on the user side
Not a cable issue, or power
Clean the monitor screen to eliminate dust as a possibility
Damp cloth that wont scratch screen
Replace entire display
May be the only option
Flashing screen
Suddently disappears and reappears intermittently
CHeck the video cable connnections
Loose cable
Replace
Proble could be the monitor
Confirm OS display settings first to rule this out
Driver or Config settings may not match the monitor
Incorrect Display Color
Color not represented properly
Entire tint or wash of color that is unwanted
Check Tint in Monitor settings
Perform factory reset of monitor config
Driver on OS - any tint or color mode settings there
Check OS in case it has red-eye / night mode coloring
Audio Issues w/ Monitors – no sound / low volume
Controls for audio on Monitor? Check volume / Mute
Confirm audio feed Input to the Monitor
Separate audio cable? Or coupled?
HDMI
Thunderbolt
DisplayPort
Check for Audio Jacks
Monitor config has setting to choose which input it sends to speakers
Multiple Interfaces to accept?
Analog
Digital
INtegrated
Dim Image
Check monitor brightnes/ contrast settings
Match to lighting of your work area
Check the OS – Modify in Driver settings
Auto-dimming / time of day
Dim on Battery Power
Display seems black but almost visible behind it
Backlight failure
Even only a section of screen could be out
Replace Backlight or Entire Display
LCD Projector Troubleshooting
Large screen projection
Conference rooms, large gatherings
Referred to as ‘LCD’ projector – NOT ALWAYS IS
Metal-Halide lamp
Very bright
Very hot
Relatively expensive
$35 to $350
Always leave the fan running when you turn off
Cool bulbs
Extend lifetime of the light
Intermittently Shuts Down
No light output
COoling Problem?
Check cooling vents, is Fan Running?
Temperature Sensors inside blocked?
Clean out dust on outside of projector
Air filters need replacing?
TROUBLESHOOTING MOBILE DEVICES
Poor Battery Health
Replace aging batteries
there’s a limited number of lifetime Recharges
Bad Reception
Always searching for signal = battery consumption
Use Airplane mode on the ground
When out of range of service in a dark / unecessary territory
Disable unnecessary features
Additional services disabled - 802.11, BT, GPS radios
Check Application usage
Check Application Battery Usage
Settings > Battery (Android and iOS)
Swollen Battery
Buildup of gas
Battery package designed to self-contain gas
DO NOT open the battery packet / container
Do not puncture
Fire Risk
Faulty Battery
Stop using immediately
Dispose of properly - HAZ WASTE facility
Broken Screen
Perform Backup
Time for a backup before anything else
Replacing the Screen
No easy fixes – entire display including glass needs replacing
Exercise caution – glass is v sharp
Use tape to hold broken bits in place – prolong use temporarily
Buy yourself enough time to backup safely
Improper Charging
Troubleshoot through process of elimination
Check everything in the charging process
Check Cable Interface
Lint, dirt, etc…
Remove any obstructions from port
Be careful not to damage pins!
Check the Cable
Don’t use frayed or damaged cables
Try a known-good cable
From another working device
Verify the Power Adapter specs
Check with a multimeter
Are voltages from AC source and output voltage correct?
Poor or Zero Connectivity
Cellular or Wi-Fi has many variables affecting reception
Hint: Location is everything
Most people notice dropouts upon moving from buildings/rooms
Cellular
Signal Strength meter
How much signal are we receiving at this exact location?
Is Outdoor connectivity better?
Wi-Fi
Distance
Limited range
Config a different Channel/Freq – unimpeded bandwidth
Interference can limit throughput, cleaner signal is better
Liquid Damage
Warranty terms for device WON’T cover this
Phones can have an indicator telling if it’s been breached
Liquid Contact Indicator - LCI
Turns color when liquid has been present
Placed in multiple points throughout phones, tablets
Power down and strip device immediately
Do not power it back on
Do not plug it in
Remove all components possible
Case, cards, back cover, battery
Rice doesn’t really work – Use Silica gel instead
Desiccants
Don’t disturb or do anything with it while water inside
Don’t turn on
Don’t charge
Don’t connect
Don’t press keys
Don’t heat!!!
Don’t move
Wait at least 1 day minimum in a very dry area
Or until phone appears to be dry
And err on the side of waiting longer than that
Once you’re sure Power On again
This is the only check left at this point
Overheating
Temperature Sensors
Phones will automatically shut down
Common heat causes
Discharging the battery
Charging the batter
Using the display
CPU usage
Check the Apps usage
Application Resource Usage utility
See resource consumption
Some apps use a lot of CPU
Avoid Direct Sunlight
Digitizer Issues
Touchscreen completely black – not responding to input
Need to do a Reset
Apple iOS reset
iOS reset – Press power button, slide to power off, press power button
… Hard reset – Hold down power + Home + Vol for 10 seconds
Android reset:
Android reset – Remove battery, put back in, power on
… Hard reset – Hold down power and vol until restart
Physically Damaged Ports
External interfaces only built for normal wear and tear
Only charges if cable is put in a certain orientation, direction
Accidents? Tripping cable, bent connecter, rough handling
Not charging? Do a visual inspection
Replacement is troublesome – integrated onto system board
Not modular
Usually requires an entire replace of that mobo
Malware
Always a concern – even on mobile
Look for Symptoms a new malignant app is running
Strange apps we never isnatlled
Large Data transfers
Pop up messages
High CPU usage / overheating abnormally
Battery continually depleted sooner
Try a security App or scanner
3rd-Party Virus Scanner
Identify malware infections
Cursor drift
Random input or cursor moves w/o touching device
Similar issues with phone, though more rare
Common on Older screens
Use a Touch calibration app
Requires user input – touching certain areas of screen
Should solve cursor drift
TROUBLESHOOTING PRINTERS
Critical last step of printing process is the printer functions
Testing the Printer
Print or scan a test page
Windows (built-in):
Printer Settings or Properties tab
Message printer to print standard test page from Windows
Determines Windows config is correct
Connection between Device and Printer is working
Printer itself is functioning fully
Diagnostics in Printer
Accessing data from printer console
Test functions built into printer
Web-based utilities
Vendor specific
Generic utilities
E.g. Test page output
Issues with Test Page Output
Looking for abnormalities from the above example (expected)
Research what common causes of observed errors could be
Inkjet + Vertical line showing down page
Time to clean Print Heads / Replace Print Heads
Laser + Vertical line down page
Scratch on Photosensitive Drum - Needs replacing this (w/ Cart?)
Faded printing, blank entirely
Fill toner (laser)
Fill ink (inkjet)
Doubling / Echo images or speckling
Laser - Optical drum not self-cleaning properly
Ghost / “shadow” of earlier print image repeated
Garbled print
All 1’s and 0’s
Wrong printer Driver / Wrong model?
Incorrect page description language
PCL > PostScript
Or PostScript > PCL
Test print from printer itself (internal)
Verify it’s own functionality
Troubleshoot the application after – correct printer model
Change printer driver
Adjust configuration of existing printer driver
Toner not sticking to paper – smudging on touch
Not fused to the page fully
Toner sticks to everything and smears
Fuser may not be heating it up or working properly
Easy to access and replace this
Unhook and slide Fuser Assembly out of printer, and replace
Incorrect Size Paper
Printers have ranges theyre expecting to receive
E.g. Print a Legal page to a Letter size paper
Printer Stops – Paper Tray notification
Gives you a chance to fix the issue before printing
Replace the paper in that tray
Modify configuration on device to match the printers’
Paper Jam
Lots of twists and turns
Remove Paper while carefully not leaving any behind
Picking up incorrectly
Pick up multiple
Check Paper Tray for proper function, no damage
Check out Pickup Rollers, observe a single page passing
Worn, damaged rollers?
Replace rollers individually or as part of Maintenance Kit
Papers are creased upon exist
Some defect along rolling path
Check it again
Wrong weight of Paper
Check Documentation for Printer to get optimal suggestion
Multiple Prints Stopped in Queue
Corrupted print jobs causing entire Print process to crash
Lots of jobs adding to Queue but nothing printing….
Print Spooler crashing
Most spooler configs will automatically restart
IF it fails the 1st and 2nd time.. This is automatic
IF it fails beyond that, Service will take no action / no restart
Print spooler remains in a stopped state - backed up queue
Continued Spooler Crashing Issues
Looking for pattern / data to help us troubleshoot
Windows Event Viewer
Look for Windows Print Service tagged events
What happened during crash + subsequent events
Single Print Job Can be repeatedly Crashing all prints
Delete this print job
Monitor to verify it was the one causing the issue
Incorrect Color Settings
Getting printer to match the display color on the screen
E.g. for Designers
Calibration of Screen first – accurate model
Some can be done w/o any additional tools
3rd-Party Calibration = more certain though – accurate and professional
Check the Paper – bright white
Best color representation
Calibrate the Print Color
Tool for Balancing proper amounts of ink / toner
Grinding Noises
Mechanisms inside device failing / malfunctioning?
Paper jammed inside Printer Path?
Carriage (Inkjet) stuck on rail / blocked from moving across Page
Different process for Removal of Jams or Mechanical Solutions
Check Documentation for Printer to find the correct process
May require additional Maintenance / Repair order from Outside
Order replacement parts
Replace entire printer
Relatively Simpler fixes too
Someone just replaced Ink cartridges incorrectly – Reseat them
Finishing Issues
What happens after output, providing additional function
Collate, Bind, Staple, etc.
Staple Jams
Larger printers will collate and staple them in groups
Each Manuf. Has different removal process for Stapler / Cleaning
Check docum.
Hole-punching location
Incorrect placement or number than specified
Check print driver that correct settings were inputed
Check that they match configuration of the printer
Page Orientation
Portrait > Landscape … Landscape > Portrait
Wrong Selection given to Print Driver
Print Driver is defective
Update
Printer has a Default preference
Check the settings on the printer console
This could override the messages sent in – universal rule
TROUBLESHOOTING NETWORKS
Hard situation for Users – attempting to contact a device but no response
When there appears to be Zero Connectivity at all
No Network Connectivity
We start at the Local Device and work our way outward….
Link Light (Traffic indicator LED)
Associated with Ethernet interface
Check Light from the Switch
Switch getting signal from the device?
Blinking?
Connected? Test How far comms can get along Network
Ping the loopback IP address (device’s internal IP) - 127.0.0.1
Basic Sucess = Protocol stack working
Variation = Availability and Intermittency of Connectivity?
Ping local IP address of NIC
Checks local configuration, adapter, and link signal
Physical adapter is working? Config is working? Connected to Network?
Ping Default Gateway – Network’s External Interface
Connectivity of the local network
Every Network has one
Critical link between US and Rest of World
Def Gateway responds?
Packets are being received. Packets sent back in return
Connected to Internet? Ping a major server on the internet
E.g. Microsoft.com … google.com … apple.com .. etc.
Ping devices on Router’s other side – 8.8.8.8 / 1.1.1.1 / 9.9.9.9
This establishes we can communicate to Internet & back w/o trouble
Intermittent Wireless Connectivity
If on a Wi-FI network and partial pings returning?
Band Interference causing Packet loss or Ping dropouts
Other devices nearby using Our WAP’s same frequency?
Check Signal Strength on Device – close enough Distance?
Need enough proximity to get packets there and receive back
Transmitting Antenna good?
Transmitting Signal good?
Receiving Antenna good?
Best Channels for communication in WAP
Can be auto-configured to Select best frequency bands for that area
Check Freqs config’d in WAP – Manual tuning or Automatic?
Manually config different channels – performance improves?
Signal Bounce and Latency - physical barriers / materials
Check for multipath interference / Flat surfaces
Move to better point
Incorrect Access Point placement
Need closer location toward Users?
Move Users towards it?
Wireless Interference Analysis
OS may have built-in tools to display data on signal interference
3rd-Party utility showing Signal vs. Noise
Predictable Sources of Interference
FLueorescent lights
Microwave ovens
Cordless phons
High-power sources
Unpredictable Sources / Uncontrollable / Public Areas
Multi-tenant buildings – Lots of networks
Use simple Utility measuring using SNR (signal-to-noise ratio)
Use Performance Monitor (Windows) to break that out in more detail
Signal to Noise
Signal = good (green))
Noise = other shit (red)
Ratio is the critical factor
1:1 is basically impossible to filter out and get useful data
Need a much better tilt towards Signal
Limited or No Connectivity (per Windows system data)
System Tray (Windows)
NIC status updates
“No Internet Access”
“Limited or No Connectivity”
Check Local IP Address
Check if it has been assigned by DHCP and/or Manually preconfig’d
APIPA address? DHCP process failed – local connectivity only
Link local address instead
DHCP addy obtained? Perform the Regular Ping Tests
Check local gateway, Remote IP address (i.e. DNS)
Jitter – Delay-based Loss or Distortion of Real-Time comms
Common in VoIP / Streaming video
Robotic glitches, dropouts
Normally data should arrive at regular intervals
Missed packets are gone – no retransmission
Feed keeps moving forward – continue with conversation
Are subsequent packets getting through okay now?
Jitter - useful Statistic to observe the quality
How well our network is performing with these RT protocols
Time between frames
Significant intervals can cause data loss
Improving Poor VoIP quality
Configure for High Speed & Low Latency for best results
RT apps are demanding
Check if anyone else using Bandwidth on our shared connection
If someone’s hogging most of it, we’re going to have a bad call
Verify Local Networking equipment – age, condition? Replace?
Can they maintain the high speeds needed on modern networks?
Packet Capture – View the network Performance
See packets themselves if you want to prove anything concrete
Where the problems are occurring
Latency
A delay between Request → Response
This value determines our upper limit of information that can be transferred
A nominal amount is normal and expected
Problems when 1+ steps along the way exceed normal latency behavior
Examine the Response Times at every step along the way
Could require multiple Measurement tools….
Measuring each Network along the way – what Latency is normal?
Packet Captures – detailed and granular analysis of both-way traffic
How much time is occurring from 1 frame to another?
Getting measurements down to the Microsecond
Visible difference between Good and Bad latency
Port Flapping
Connected to hard-wired Ethernet network…
NIC / Link light turning on & off repeatedly
Solid to dark
Port Flapping – some physical issue in between 2 devices
Check the physical Media themselves
Cable tester – can it support the used Speeds / Standards?
Replace the Cable if that was it
Check the Hardware
CHeck after moving to different interface on device (Switch)
Port flapping resolved? Or did it remain?
A single port may be the problem
Issue is NOT the Switch if the problem follows on other Interfaces
Problem could be with your device
Change out your computer or Network Interface Card
Change out Cable here too if necessary for certainty