Contents
7 Steps of The “Network Troubleshooting Methodology” ..................................................................................................... 7
6 Steps of the CompTIA Troubleshooting Methodology ........................................................................................................ 7
Keep In Mind!.......................................................................................................................................................................... 7
Hardware ................................................................................................................................................................................ 8
Monitors.............................................................................................................................................................................. 8
Digitizer ........................................................................................................................................................................... 8
Inverter............................................................................................................................................................................ 8
Only CRT TVs can be Degaussed ..................................................................................................................................... 8
Docking Stations & Port Replicators ................................................................................................................................... 8
Point-of-Sale Workstation................................................................................................................................................... 8
Signature Pads................................................................................................................................................................. 8
SODIMM .............................................................................................................................................................................. 8
Troubleshooting .................................................................................................................................................................. 9
‘POST Code Beeps’ .......................................................................................................................................................... 9
Continuous Reboots ........................................................................................................................................................ 9
Laptops Have a CMOS Battery Too ................................................................................................................................. 9
Computer Won't Boot But Fans Spin .............................................................................................................................. 9
Don’t use power tools when fixing laptops - electrical motors can generate Electro-Magnetic Interference (EMI)! ... 9
Broken Pins on a VGA Cable............................................................................................................................................ 9
‘Bootable device not found’ error?................................................................................................................................. 9
PCIe x8 Card in a PCIe x16 Slot (Official CompTIA answer below, largely incorrect in the real world) .......................... 9
ITX is a series of form factors which began with the mini-ITX, but there is no specific size called ITX. ......................... 9
Tools .................................................................................................................................................................................. 10
Loopback Plug ............................................................................................................................................................... 10
Crimper ......................................................................................................................................................................... 10
Cable Tester .................................................................................................................................................................. 10
Punchdown Tools .......................................................................................................................................................... 10
Tone Generator & Probe............................................................................................................................................... 10
Time-Domain Reflectometer ........................................................................................................................................ 10
USB .................................................................................................................................................................................... 11
Watts n’ Speed .............................................................................................................................................................. 11
USB Hubs ....................................................................................................................................................................... 11
Thunderbolt ...................................................................................................................................................................... 11
HDDS & RAID ..................................................................................................................................................................... 11
Index
Upgrading Internal Storage - Don’t select NAS or SAN when asked to! ....................................................................... 11
Laptop HDDs: 2.5” vs 1.8” & Micro-SATA ..................................................................................................................... 11
RAID............................................................................................................................................................................... 11
HDDs with differences in speed and manufacturer may not be RAID compatible! ..................................................... 11
Power Supply Units (PSUs) ................................................................................................................................................ 12
Selecting PSUs to Travel ................................................................................................................................................ 12
525W PSUs are a thing, apparently! ............................................................................................................................. 12
Never attempt to fix a broken PSU, or even its fans! ................................................................................................... 12
PSU Connectors & Pin-Counts....................................................................................................................................... 12
RS232C .............................................................................................................................................................................. 12
DVI-I vs DVI-D vs DVI-A...................................................................................................................................................... 13
Motherboard Size Comparison ......................................................................................................................................... 13
Networking & Wireless ......................................................................................................................................................... 14
Network Types .................................................................................................................................................................. 14
Metropolitan Area Network (MAN) .............................................................................................................................. 14
Wireless Mesh Network (WMN) ................................................................................................................................... 14
Local Area Network (LAN) ............................................................................................................................................. 14
Personal Area Network (PAN) ....................................................................................................................................... 14
Wide Area Network (WAN) ........................................................................................................................................... 14
Networking Devices .......................................................................................................................................................... 15
Routers .......................................................................................................................................................................... 15
Hub ................................................................................................................................................................................ 15
Switch ............................................................................................................................................................................ 15
Managed Switch............................................................................................................................................................ 15
Optical Network Terminal (ONT.................................................................................................................................... 15
Cable Modems .............................................................................................................................................................. 15
Very Small Aperture Terminal (VSAT) Microwave Antenna ......................................................................................... 15
Microwave Links............................................................................................................................................................ 15
DSL..................................................................................................................................................................................... 16
Cable Details ..................................................................................................................................................................... 17
Types ............................................................................................................................................................................. 17
Crossover Cables ........................................................................................................................................................... 17
Straight-Through / Patch Cable ..................................................................................................................................... 17
Serial Cable.................................................................................................................................................................... 17
Patch Panels .................................................................................................................................................................. 18
Cable Range................................................................................................................................................................... 18
Index
CAT: Cables Chart .......................................................................................................................................................... 19
CAT: Power over Ethernet (PoE), PoE+, and VoIP ......................................................................................................... 19
Quality of Service (QoS) ................................................................................................................................................ 19
MTU (Maximum Transmission Unit) ............................................................................................................................. 19
Fiber .................................................................................................................................................................................. 20
Connectors .................................................................................................................................................................... 20
"Fiber to the X" ............................................................................................................................................................. 20
IP Address Details.............................................................................................................................................................. 21
Types ............................................................................................................................................................................. 21
IPv6 Address (vs IPv4 & MAC Addresses) ..................................................................................................................... 21
Loopback Address ......................................................................................................................................................... 21
Broadcast Address ........................................................................................................................................................ 22
Multicast Address ......................................................................................................................................................... 22
Misc. IP Network Terminology .......................................................................................................................................... 22
Dynamic Host Configuration Protocol (DHCP) Server ................................................................................................... 22
Default Gateway ........................................................................................................................................................... 22
Wi-Fi .................................................................................................................................................................................. 23
Wi-Fi Bands and Channels ............................................................................................................................................. 23
Wi-Fi Generations ......................................................................................................................................................... 23
DNS Record Types ............................................................................................................................................................. 25
Network Parameters & Delays .......................................................................................................................................... 26
Jitter .............................................................................................................................................................................. 26
Latency .......................................................................................................................................................................... 26
Throughput ................................................................................................................................................................... 26
Bandwidth ..................................................................................................................................................................... 26
Crosstalk ........................................................................................................................................................................ 26
Troubleshooting ................................................................................................................................................................ 26
Split Horizon .................................................................................................................................................................. 26
DNS Issues ..................................................................................................................................................................... 26
Decreased Speeds from bad NIC Drivers ...................................................................................................................... 27
Steady Lights on a Network Interface Card (NIC) ......................................................................................................... 27
Web Servers should be configured to accept requests through HTTP or HTTPS and provide resources back to
requesters ..................................................................................................................................................................... 27
Cloud Computing & Virtualization ........................................................................................................................................ 28
Cloud Terminology ............................................................................................................................................................ 28
Measured Service.......................................................................................................................................................... 28
Index
Rapid Elasticity .............................................................................................................................................................. 28
On-demand ................................................................................................................................................................... 28
Resource Pooling........................................................................................................................................................... 28
‘Desktop as a Service’.................................................................................................................................................... 28
Community Cloud ......................................................................................................................................................... 28
Software-Defined Networking ...................................................................................................................................... 28
Thin Clients........................................................................................................................................................................ 28
Virtualization Tech on Intel is called VT and on AMD it’s AMD-V..................................................................................... 29
VM Network Types............................................................................................................................................................ 29
Internal .......................................................................................................................................................................... 29
External ......................................................................................................................................................................... 29
Private ........................................................................................................................................................................... 29
Localhost ....................................................................................................................................................................... 29
Type I & Type II Hypervisors.............................................................................................................................................. 29
Keyboard Video Mouse (KVM) Switch .............................................................................................................................. 29
Printers & Projectors ............................................................................................................................................................. 30
Laser Printer Components (FSD-DTPT) ............................................................................................................................. 30
Fuser Assembly ............................................................................................................................................................. 30
Separation Pad .............................................................................................................................................................. 30
Drum Unit...................................................................................................................................................................... 30
Duplexing Assembly ...................................................................................................................................................... 30
Transfer Belt .................................................................................................................................................................. 30
Pickup Roller ................................................................................................................................................................. 30
Transfer Roller............................................................................................................................................................... 30
Share a Printer .................................................................................................................................................................. 30
Printer Types ..................................................................................................................................................................... 31
3-D Printers use a filament ........................................................................................................................................... 31
Inkjet Printers use an Inkjet Cartridge .......................................................................................................................... 31
Laser Printers use Toner ............................................................................................................................................... 31
Impact / Dot-Matrix Printers use Ribbons .................................................................................................................... 31
Thermal Printers ........................................................................................................................................................... 31
Printers: Collate vs Duplex ................................................................................................................................................ 31
Steps in a Laser Printer’s Imaging Process (PCEDTFC) ...................................................................................................... 31
Troubleshooting ................................................................................................................................................................ 32
Dust on Printed Pages ................................................................................................................................................... 32
No Prints........................................................................................................................................................................ 32
Index
Projectors Keystone & Double Images.......................................................................................................................... 32
Projector Too Dim? ....................................................................................................................................................... 32
Smeared prints with a laser printer: Increase the temperature of the fuser element! ............................................... 32
Left-to-Right Faded Print on an Impact/Dot-Matrix Printer ......................................................................................... 32
Page Description Languages for Printers .......................................................................................................................... 33
Printer Control Language (PCL) ..................................................................................................................................... 33
PostScript (PS) ............................................................................................................................................................... 33
Apple Bonjour ................................................................................................................................................................... 33
Mobile Devices & IoT ............................................................................................................................................................ 34
Cellular Technology ........................................................................................................................................................... 34
3G Cellular Technology ................................................................................................................................................. 34
CDMA ............................................................................................................................................................................ 34
4G Cellular Technology ................................................................................................................................................. 34
5G Cellular Technology ................................................................................................................................................. 34
Carrier Roaming ................................................................................................................................................................ 34
Preferred Roaming Index (PRI)...................................................................................................................................... 34
Preferred Roaming List (PRL) ........................................................................................................................................ 34
Mobile Location Services .................................................................................................................................................. 35
GPS (Global Positioning System) ................................................................................................................................... 35
Cellular Radios............................................................................................................................................................... 35
Bluetooth ...................................................................................................................................................................... 35
Wi-Fi Positioning Systems ............................................................................................................................................. 35
Internal Positioning System (IPS) .................................................................................................................................. 35
Tethering vs Hotspot ......................................................................................................................................................... 35
Flickering mobile screens implies a backlight issue as per the official study guide.......................................................... 36
Internet of Things (IoT) ..................................................................................................................................................... 36
Home Automation ............................................................................................................................................................ 36
Zigbee ............................................................................................................................................................................ 36
Z-wave ........................................................................................................................................................................... 36
Troubleshooting Software .................................................................................................................................................... 37
"Pinwheel of Death” ......................................................................................................................................................... 37
The "OS Not Found" Error ................................................................................................................................................. 37
'bootrec /fixboot' .......................................................................................................................................................... 37
"bootrec /fixmbr".......................................................................................................................................................... 37
"No Boot Device Available"............................................................................................................................................... 37
"Operating system not found" ...................................................................................................................................... 37
Index
"NTLDR not found"........................................................................................................................................................ 37
"BIOS ROM checksum error" ........................................................................................................................................ 37
Always Backup First! ......................................................................................................................................................... 38
Shadow Copy..................................................................................................................................................................... 38
F12 is the most commonly used key used to enter the BIOS / UEFI boot order menu. ................................................... 38
F11 during the boot is used to boot into recovery mode on a Windows workstation. .................................................... 38
F8 is used to invoke the Advanced Boot Options menu. .................................................................................................. 38
Cybersecurity ........................................................................................................................................................................ 39
Unified Threat Management (UTM) ................................................................................................................................. 39
Preboot Execution Environment (PXE) ............................................................................................................................. 39
Secure boot ................................................................................................................................................................... 39
Intrusion Prevention System (IPS) and Intrusion Detection System (IDS) ........................................................................ 39
Authentication, Authorization, and Accounting (AAA) Server.......................................................................................... 39
RADIUS Server ............................................................................................................................................................... 39
TACACS+ Server............................................................................................................................................................. 39
MDM is for remote device management.......................................................................................................................... 39
MAM (Mobile Appln Management) is for remote enterprise app management! ........................................................... 39
SPF, DKIM & DMARC ......................................................................................................................................................... 40
Sender Policy Framework (SPF) .................................................................................................................................... 40
DomainKeys Identified Mail (DKIM).............................................................................................................................. 40
The Domain-Based Message Authentication, Reporting, and Conformance (DMARC) Framework ............................ 40
Index
7 Steps of The “Network Troubleshooting Methodology”
▪
Troubleshoot network cockups with these 7 easy to follow steps:
1. Identify the problem
2. Establish a theory of probable cause
3. Test the theory to determine the cause
4. Establish a plan of action to resolve the problem and identify potential effects
5. Implement the solution or escalate as necessary
6. Verify full system functionality and if applicable implement preventative measures, and
7. Document findings, actions, outcomes, and lessons learned.
6 Steps of the CompTIA Troubleshooting Methodology
▪
For the exam, it is important that you can list and identify these steps in order:
1. Identify the problem.
2. Establish a theory of probable cause (question the obvious).
3. Test the theory to determine the cause.
4. Establish a plan of action to resolve the problem and then implement the solution.
5. Verify full system functionality and, if applicable, implement preventative measures.
6. Document findings, actions, and outcomes.
Keep In Mind!
▪
Whether a questions asks for the “BEST” or “FIRST” solution to an issue!
Index
Hardware
Monitors
Digitizer is a touch-sensitive glass panel covering the LCD in a touchscreen assembly and is used to convert
touch events to digital signals that can be interpreted as different types of input.
Most laptops have a digitizer and an LCD screen if they are touchscreen devices.
If the touch screen is not working, but the display doesn't look cracked or broken, this is often a sign that
the Digitizer Settings are incorrect, or the digitizer is defective.
Inverter is a small green board attached to the base of the LCD panel. In a laptop computer, the LCD screen
relies on a backlight source to uniformly light up the screen, and the inverter acts as the power supply for this
lighting source. If the inverter is faulty, the display will be too dim to easily see without an external light source
like a flashlight.
Only CRT TVs can be Degaussed, if asked to deal with burn-in on Plasma and OLED displays, just say “replace”!
Docking Stations & Port Replicators
▪
▪
▪
Docking stations are a sophisticated type of port replicator designed to provide additional ports (such
as network or USB) and functionality (such as expansion slots and drives) to a portable computer when
used at a desk.
A port replicator is a simple device to extend the range of ports (for example, USB, DVI, HDMI,
Thunderbolt, network, and so on) available for a laptop computer when it is used at a desk.
The difference between a docking station and a port replicator is that a docking station can add
additional capabilities beyond what is already integrated into the laptop whereas a port replicator can
only reproduce the same ports that already exist on the laptop.
Point-of-Sale Workstation A Signature Pad is a common peripheral used with a Point-of-Sale Workstation,
not a webcam.
Signature Pads allows a customer to sign a contract or sales receipt digitally.
SODIMM Laptops and integrated PCs usually use SODIMM memory due to the memory module's smaller
footprint.
Index
Troubleshooting
‘POST Code Beeps’ is apparently not the right answer to “What’s a symptom that indicates RAM Issues?”, it’s:
Continuous Reboots
Go figure.
At the same time, another question’s solution states this: “A computer that keeps rebooting itself is a symptom of a
faulty power supply or a computer that is overheating. If the power supply is faulty, the computer will reboot itself. If the
issue is caused by an overheating issue (such as a cooling fan failure), the computer will usually reboot itself after running
for 15-20 minutes (once enough heat is built-up).” OOOFFFFFF….
Laptops Have a CMOS Battery Too apparently, remove it to get rid of troublesome BIOS settings and passwords!
Computer Won't Boot But Fans Spin continuously? It usually indicates a problem with the power supply, the
motherboard, or overheating could be occurring.
Don’t use power tools when fixing laptops - electrical motors can generate Electro-Magnetic Interference (EMI)!
Broken Pins on a VGA Cable
▪ Will cause incorrect colors to be displayed, NOT a distorted image:
o There are three rows of pins, with 5 pins per row, for a total of 15 pins in a VGA cable.
o If pins 1, 2, or 3 are missing, the display will be miscolored.
o If pins 13 or 14 are missing, the screen will not hold horizontal or vertical sync.
o The other pins are not used or are used as ground wires.
o Therefore, either the incorrect colors will show up on the screen, or the screen won't display at
all. The other options are not possible (monitor dim or black & white image).
‘Bootable device not found’ error?
The very first step we want to check is to check the physical SATA/Molex connections! This falls under step two of the
troubleshooting methodology (question the obvious). Apparently, do this before even checking the boot order!
PCIe x8 Card in a PCIe x16 Slot (Official CompTIA answer below, largely incorrect in the real world)
While a PCIe x8 card will fit into either an x8 or x16 slot, it will only run at optimal speed when placed into an x8 slot. If
the x8 card is placed into an x16 slot, it will reduce the speed to the equivalent of a 1x slot to ensure compatibility and
reliability. Even though placing an x8 card into an x16 slot is supported, it is generally considered a bad practice.
ITX is a series of form factors which began with the mini-ITX, but there is no specific size called ITX.
Index
Tools
Loopback Plug is used to test a port: it involves connecting pin 1 to pin 3 and pin 2 to pin 6.
o You can do this either by rewiring the jack or twisting the relevant pairs together on a cable stub.
Alternatively, you can purchase a prefabricated loopback plug.
o When you connect a loopback plug to a port, you should see a solid connection LED.
o You can also use the loopback plug in conjunction with diagnostic software.
Crimper is a tool used to attach an RJ-45 plastic connector to an unshielded twisted pair (UTP) or shielded
twisted pair (STP) cable.
o It pushes a portion of the plastic into the jacket of the cable to hold it in place.
Cable Tester is used to ensure a cable is properly created as a patch cable (straight through) or a crossover
cable.
o Cable testers provide detailed information on the physical and electrical properties of the cable.
o For example, they test & report cable conditions, crosstalk, attenuation, noise, resistance, and other
cable run characteristics.
Punchdown Tools are used to connect an ethernet cable to the back of a patch panel, a punchdown block, or
the back of a network wall jack.
Tone Generator & Probe: A tone generator is connected to a wall jack and sends a repeating signal over the
cable. The probe can then be used to detect which cable is attached to the wall jack by detecting the signal
being sent by the tone generator.
o The probe needs to be near or touch the cable with the tone generator attached to identify it
positively.
o While a multimeter could be used (in resistance mode) to determine if two ends of a cable are
attached to the same cable, the distance between the user's office and the communication closet
would prevent a multimeter from being used in most cases.
Time-Domain Reflectometer is used to determine exactly where in a network cable a break has occurred. Once
the location is identified, the cable can be repaired or spliced to return it to normal operations.
Index
USB
Watts n’ Speed
▪
USB 3.0 can support providing up to 4.5 watts of power per connected device.
▪
USB 1.1 supports 12 Mbps while USB 2.0 supports 480 Mbps and is backward compatible with 1.1
▪
USB devices are considered hot-swappable, and each device can draw up to 2.5 W of power over USB.
▪
USB 3.0 and 3.1 define 5 Gbps (SuperSpeed) and 10 Gbps (SuperSpeed+) rates and can deliver up to 4.5 W of
power.
USB Hubs
A USB hub is a device that connects to a USB port to allow additional USB devices to be connected to the PC, essentially
increasing the number of USB ports available.
Thunderbolt is a connector type that can be used either as a display interface (like DisplayPort) or as a
general peripheral interface (like USB 3). Thunderbolt 3 uses USB-C connectors
HDDS & RAID
Upgrading Internal Storage - Don’t select NAS or SAN when asked to!
Laptop HDDs: 2.5” vs 1.8” & Micro-SATA
A laptop hard drive usually comes in either the 2.5" form factor or the 1.8" form factor. When a 1.8" form factor is used,
the drive is connected to the laptop using a Micro SATA connector since a regular SATA connector will not fit due to the
connector's larger size.
RAID
RAID 0 provides disk striping (speed/performance) using a minimum of two disks.
RAID 1 provides mirroring (redundancy) using a minimum of two disks.
o With a RAID 1, one of the hard drives can fail while the other drive can still operate until the
bad drive is replaced.
RAID 5 provides block-level striping with distributed parity to provide redundancy using a minimum of
three disks.
RAID 10 combines disk mirroring and disk striping to protect data stored in the array and required a
minimum of four disks. Provides redundancy and double fault tolerance! Use RAID 10 if you’re building
for those requirements, even if you have an odd number of disks such as 5 disks!
HDDs with differences in speed and manufacturer may not be RAID compatible!
Even 1TB Seagate 5400RPM and 1TB WD 7200RPM drives may be incompatible! Though it may seem that a bad SATA
cable may be the likely cause of a "RAID ARRAY DISK1 FAILURE" message, it’s more likely the different drives!
Index
Power Supply Units (PSUs)
Selecting PSUs to Travel - Apparently when building PCs for travel, the Input Voltage (110V vs 220V) is the
biggest deal ever because apparently voltage transformers are not a thing that even a full production crew can
carry out. Go figure.
525W PSUs are a thing, apparently!
Never attempt to fix a broken PSU, or even its fans!
If the fan in the power supply is faulty, replace the entire power supply. You should never attempt to repair or fix a
broken power supply or broken power supply cooling fan due to the power supply's high voltage electrical components.
When a fan creates a grinding sounds, this is evidence of an impending failure, and the device needs to be replaced.
Technicians should never open a power supply or replace any of its internal components, therefore the entire power
supply should be replaced in this scenario.
PSU Connectors & Pin-Counts
Molex Connector provides DC power to the various drives inside a computer case. Molex and
Mini-Molex are both 4-pins connectors, with Mini-Molex only being used to support floppy disk drives.
SATA Connectors have 15 pin and 7 pin varieties.
Thunderbolt has 20 and 24 pin varieties.
SCSI has 50 and 36 pin varieties.
RS232C DE-9, often mistakenly referred to as a DB-9 port used to be the industry standard for serial data
transmission.
▪
▪
▪
A RS-232 serial port was a standard feature of personal computers as it was the preferred way to
connect modems, keyboards, mice, external storage and many other peripheral devices.
First introduced in the 60s, RS-232 is a protocol that defines how the data is transferred, bit by bit from
a Data Terminal Equipment (DTE) such as a computer terminal, to Data Communication
Equipment (DCE) such as a modem.
The most convenient and least expensive way to connect a RS-232 printer to a network would be to
buy an RS-232 to RJ-45 adapter, which will allow you to connect the legacy printer to the network
directly.
Index
DVI-I vs DVI-D vs DVI-A
I: Integrated, digital + analog signal; single or dual link
D: Digital only; single or dual link
A: Analog only
Motherboard Size Comparison
Index
Networking & Wireless
Network Types
Metropolitan Area Network (MAN) is a computer network that interconnects users with computer resources in
a geographic region of the size of a metropolitan or city area. This usually works by providing municipal
broadband via Wi-Fi to large parts or all of a municipal area by deploying a wireless mesh network.
Wireless Mesh Network (WMN) is a wireless network topology where all nodes, including client
stations, can provide forwarding and path discovery to improve coverage and throughput compared to
using just fixed access points and extenders. The typical deployment design uses hundreds of wireless
access points deployed outdoors, often on poles.
Local Area Network (LAN) is a network where all the nodes or hosts participating in the network are directly
connected with cables or short-range wireless media.
Personal Area Network (PAN) is a close-range network that is usually based on Bluetooth or NFC for
communications between personal devices, such as smartphones, laptops, printers, and other peripheral
devices.
Bluetooth is a wireless technology standard used for exchanging data between fixed and mobile devices
over short distances using UHF radio waves in the industrial, scientific, and medical radio bands from
2.402 GHz to 2.480 GHz and building a personal area network (PAN).
NFC requires devices to be within 4cm of each other
Wide Area Network (WAN) is a network that spans multiple geographic locations such as the internet. Wide
area networks are often established with leased telecommunication circuits. Your ISPs network to your home
is an example!
Q: Your home network has a wireless access point (WAP) that allows your smartphone and tablet to connect
to your internal network. The WAP is connected to a router and a cable modem to provide internet access. A
coaxial cable carries the network traffic from the cable modem to the cable company’s central office for
transmission to and from the internet. Which of the following types of networks would best describe this
network configuration between your home network and the internet through your cable modem
connection?
A: WAN
Index
Networking Devices
Routers can connect LANs to WANs, something that should have been obvious given that’s the device you’ve
installed at home to access the global internet.
o A router is a network device that links dissimilar networks and can support multiple alternate paths
between locations based upon the parameters of speed, traffic loads, and cost.
o Routers are used to logically divide networks into subnets.
o A router or other gateway device must be installed between two VLANs to allow connections to be
routed between them.
▪ A Virtual LAN (VLAN) is a logically separate network that is created using switching technology:
even though hosts on two VLANs may be physically connected to the same cabling, local traffic
is isolated to each VLAN so they must use a router to communicate.
Hub provides no intelligence in its interconnection functions so that whatever is received on one port is
repeated out every other port. This leads to many collisions occurring on the hub and increases the number of
rebroadcasts which slows down the entire network.
Switch is a network device that receives incoming data into a buffer, then the destination MAC address is
compared with an address table so that data is only sent out to the port with the corresponding MAC address.
o In a switched network, each port is in a separate collision domain.
Managed Switch is a switch with advanced networking functions and security settings that can be enabled and
configured by an administrator.
Optical Network Terminal (ONT) is a device that connects fiber optics cables to other types of wiring such as
Ethernet and phone lines by converting the signal from optical to electrical and vice versa. An ONT is
commonly used with fiber to the house (FTTH) installations.
Cable Modems Cable providers will install these devices called ‘Cable Modems’ to get internet into your house
through a coax cable. It looks like a router but isn’t! There’ll be a separate router installed too.
A cable modem is a type of network bridge that provides bi-directional data communication via radio
frequency channels on a hybrid fiber-coaxial (HFC), radio frequency over glass (RFoG), and coaxial cable
infrastructure.
Cable modems are primarily used to deliver broadband internet access as cable internet, taking advantage of
an HFC and RFoG network's high bandwidth.
Satellite systems provide far bigger areas of coverage than can be achieved using other technologies. A
Very Small Aperture Terminal (VSAT) Microwave Antenna is aligned to an orbital satellite that can either relay
signals between sites directly or via another satellite.
Microwave Links require a direct line of sight (LoS) between the antennas to maintain a strong and effective
link. These line-of-sight microwave links uses highly directional transmitter and receiver antennas to
communicate via a narrowly focused radio beam.
Index
DSL
DSL is a technology used to transmit multimedia traffic at high-bit rates over twisted-pair copper wire (over
ordinary telephone lines, also called “POTS” – Plain Old Telephone System!). This allows the
telecommunications company to connect a user's home to the local switching center using normal telephone
lines, then connect that local switching center (using a DSLAM (DSL Access Multiplexer) to multiplex the
connections) to the central office over a single high-speed cable (such as a fiber connection).
POTS (Plain Old Telephone System) is an older standard used for telephone systems. An RJ-11 wiring standard
is used to terminate both ends of a standard phone line. This is also used for DSL lines and VoIP ATA (Analog
Telephony Adapter) devices.
Q: Which type of internet connection is terminated at a local switching center and requires a different media
type between the switching center and the end customer?
A: DSL
Q: Which type of internet connection allows for high-speed bi-directional data communication over a hybrid
fiber-coaxial (HFC) connection?
A: Cable (See ‘coax’? Say Cable!)
Index
Cable Details
Types
Coaxial Cable is a cable used to transmit video, communications, and audio.
o A coaxial or coax cable is most commonly used as a cable to connect a TV to a cable TV service.
o Coaxial cables are a specialized type of copper cabling that uses a copper core to carry the electrical
signal while being enclosed by plastic insulation and shielding to protect the data transmission from
the effects of electromagnetic interference (EMI).
o Both RG-6 and RG-59 are cable types used for coaxial cable connections. RG-6 cabling is recommended
for your Cable TV, satellite, TV antennas, or broadband internet. RG-59 cabling is generally better for
most CCTV systems and other analog video signals.
Plenum-rated Cable has a special insulation that has low smoke and low flame characteristics.
o Plenum cable is mandated to be installed in any air handling space.
Shielded Cables contain a braided foil shield around the inner cabling to protect the data from the effects of
electromagnetic interference (EMI).
STP (Shielded Twisted Pair) is a type of cabling that can help prevent electrical interferences or crosstalk.
▪ A cross-talk is when electrical interference data passing through can cause CRC (Cyclic
Redundancy Check) Errors.
▪ A CRC is used to calculate checksums before and after data transfers to ensure accuracy.
o If electrical interference gets in the way, such as proximity to fluorescent light bulbs, it can cause data
to be corrupted and produce an error.
Optical Fiber Cables consists of an ultra-fine core of glass to carry the light signals surrounded by glass or
plastic cladding, which guides the light pulses along the core, and a protective coating.
o The fiber optic cable is contained in a protective jacket and terminated by a connector.
o Fiber optic cables use light signals to carry data across a cable at extremely high bandwidths.
Crossover Cables should be used to connect two similar devices (PC to PC, Router to Router, Switch to Switch,
etc.) to create a network. For an ethernet cable, this should be a network cable with a T568A wiring standard
on one end and a T568B wiring standard on the other end of the cable to create a crossover cable.
Straight-Through / Patch Cable is a network cable that uses the same wiring standard on both ends such as
T568A to 5T568A or T568B to T568B and is used to connect complimentary devices, such as PCs to routers.
Serial Cable is a data cable that transmits data a single bit at a time. A DB-9 connector is used to terminate an
RS-232 serial cable.
Index
Patch Panels
A patch panel is a device or unit featuring a number of jacks, usually of the same or similar type, for the use of
connecting and routing circuits for monitoring, interconnecting, and testing circuits in a convenient, flexible
manner. Patch panels are commonly used in computer networking, recording studios, and radio and
television.
A patch panel is used in a structured cabling system. For example, a computer is connected to a wall jack
which is in-turn connected to a patch panel via cabling running through the walls. The pre-wired RJ-45 port on
the patch panel is then connected to the network switch using a straight-through or patch cable.
Cable Range
Shielded & Plenum Copper Cables can only cover a distance of approximately 100 meters in length.
Coaxial Cables can cover a maximum distance of 200 to 500 meters in length.
Fiber Optic Cables are network cables that contains strands of glass fibers inside an insulated casing. They're
designed for long-distance, high-performance data networking, and telecommunications. If you are dealing
with connecting two networks over a long distance (over a few hundred meters), you should use a fiber optic
cable.
Index
CAT: Cables Chart
CAT: Power over Ethernet (PoE), PoE+, and VoIP
▪ VoIP (Voice over IP) devices that rely on PoE (Power over Ethernet) should use a CAT 5e, CAT 6, or
higher cable to make the connection. This allows a single cable (CAT 5e or CAT 6) to carry both the data
and the device's power. POE is defined in the IEEE 802.3af.
o Fiber, coaxial, and CAT 3 cables cannot carry power to the VOIP device and cannot be used to
meet this requirement.
o Using a CAT 5e or CAT 6 cable, you can connect two devices of approximately 300 feet (100
meters) without any need to repeat the signal.
o The 802.3af (PoE) standard can support up to 15.4W of power at up to 100m distance.
o The 802.3at (PoE+) standard can support up to 25W of power at up to 100m distance.
o PoE+ can support higher-powered devices such as PTZ cameras, door controllers, and thin client
computers.
▪ To prevent VoIP calls from being dropped,
Quality of Service (QoS) should be implemented on the switch: QoS means using a network protocol to
prioritize certain traffic types over others
o Enterprise networks can use QoS protocols to make sure traffic such as Voice over IP calling or
video conferencing is given higher priority than traffic where packet-timing is less important,
such as ordinary file downloads.
MTU (Maximum Transmission Unit), is the largest unit that can be transmitted across a network. If the
MTU is set at a value above 1500, the network is configured to support jumbo frames.
Placing VoIP devices on a separate VLAN is performance optimization!
Index
Fiber
Connectors: A ST, SC, LC, or MTRJ connector is used to terminate a fiber optic cable.
ST (Straight Tip) Connector is a quick-release
bayonet-style connector that has a long
cylindrical connector.
SC (Subscriber/Standard Connector) is a
general-purpose push/pull style connector
that has a square, snap-in connector that
latches with a simple push-pull motion.
▪ SC connectors are widely used in
single-mode fiber optic systems.
LC (Lucent Connector) is a small form factor
connector that combines the transmit
and receive cables into a single square,
snap-in connector.
F-Type Connector is used with coaxial cables,
not fiber optic cables.
"Fiber to the X"
"Fiber to the X" (FTTx) is commonly used to describe where the fiber connection ends between the service and
the subscriber. The closer the fiber is to the user's network, the faster the service:
FTTH (Fiber to the House) provides fiber directly to the user's home network making it the fastest option.
Traditionally, you will find a 1 Gbps connection or higher with FTTH.
FTTN (Fiber to the Node) or FTTC (Fiber to the Curb/Cabinet) provides fiber only to the local area or
neighborhood but then uses copper cabling from the node/cabinet/curb to the home network, which slows
down the network (generally, 100-200 Mbps).
HFC (Hybrid Fiber Coax) is similar to FTTN/FTTC, except that coaxial cable is used from the cabinet to the home
to increase the speed (generally 300-500 Mbps).
Index
IP Address Details
Types
Static IP Address is used when the DHCP server is disabled & clients are configured manually to join the network
properly.
Automatic Private IP Addressing (APIPA) is a feature of Windows-based operating systems that enables a
computer to automatically assign itself an IP address when there is no Dynamic Host Configuration Protocol
(DHCP) server available to perform that function.
o When a host uses an APIPA address, it can communicate with other hosts on the same network using
APIPA, but it cannot reach other networks or communicate with hosts who have managed to obtain a
valid DHCP lease.
o Any address from 169.254.1.0 to 169.254.254.255 is considered an APIPA address.
Link-Local Address are also known as APIPA addresses, but apparently is the IPv6 variant
Private IP Addresses are in the range of 10.x.x.x, 172.16-31.x.x, or 192.168.x.x
Localhost IP is 127.0.0.1
Public IP Addresses - All others are considered Public IP Addresses.
IPv6 Address (vs IPv4 & MAC Addresses)
IPv6 Addresses are written as a series of up to 32 hexadecimal digits, but can be summarized using a :: symbol. The ::1 is
the IPv6 address for the localhost.
IPv4 Addresses consists of 32 bits. IPv4 addresses are written in dotted octet notation, such as 192.168.1.254.
MAC Addresses are written as a series of 12 hexadecimal digits, such as 00:AB:FA:B1:07:34. The other option,
192:168:1:55 is not a valid address since it uses : instead of a . in between the octets.
Loopback Address
▪ Loopback is the routing of signals or data streams back to their source without processing or
modification, and is used primarily as a means of testing communications infrastructure.
▪ In IPv6 the Loopback Address is ::1. In IPv4, the loopback address is 127.0.0.1.
o The loopback address is used to send a test signal to diagnose problems.
o If there is no communication of the return packet, this indicates the network card is faulty, the
cable/loopback is loose, or there is bad wiring of the loopback plug.
Index
Broadcast Address is an IP address that is used to target all systems on a specific subnet network instead of
single hosts.
Multicast Address is a logical identifier for a group of hosts in a computer network that are available to process
datagrams or frames intended to be multicast for a designated network service.
Misc. IP Network Terminology
Dynamic Host Configuration Protocol (DHCP) Server
▪ A DHCP server is a server configured with a range of addresses to lease. Hosts can be allocated an IP
address dynamically or be assigned a reserved IP address based on the host's MAC address. The server
can also provide other configuration information, such as the location of DNS servers.
Default Gateway
A default gateway is the node in a computer network using the Internet protocol suite that serves as the
forwarding host (router) to other networks when no other route specification matches the destination IP
address of a packet.
A gateway is a network node that serves as an access point to another network, often involving not only a
change of addressing, but also a different networking technology.
More narrowly defined, a router merely forwards packets between networks with different network prefixes.
The networking software stack of each computer contains a routing table that specifies which interface is used
for transmission and which router on the network is responsible for forwarding to a specific set of addresses.
If none of these forwarding rules is appropriate for a given destination address, the default gateway is chosen
as the router of last resort. The default gateway can be specified by the route command to configure the
node's routing table and default route.
Index
Wi-Fi
Wi-Fi Bands and Channels
▪ The Wi-Fi frequency band for 2.4 GHz is split into 14 channels of 5 MHz each.
United States and Canada, only channels 1 through 11 may be used.
Europe, channels 1 through 13 may be used.
Japan, channels 1 through 14 may be used.
▪ With wireless access points that run 2.4 GHz frequencies, you can only select channels between 1 and
11 in the United States. This includes 802.11b, 802.11g, 802.11n, and 802.11ax networks.
To Prevent Overlapping of the Channels, you should select channels 1, 6, and 11. By doing so, you can
increase the reliability and throughput of your wireless network.
o Since each Wi-Fi communication requires approximately 20 MHz to operate effectively, users
should set their wireless access points to channels 1, 6, and 11 to minimize interference and
avoid overlapping channels.
Wi-Fi Generations
Maximum
Linkrate
(Mbit/s)
Generation
IEEE
Standard
Wi-Fi 7
802.11be
1376 to 46120
802.11ax
574 to 9608[1]
Wi-Fi 6E
Adopted
(2024)
Radio
Frequency
(GHz)
2.4/5/6
2020
6[2]
2019
2.4/5
433 to 6933
2014
5[3]
Wi-Fi 6
Wi-Fi 5
802.11ac
Wi-Fi 4
802.11n
72 to 600
2008
2.4/5
(Wi-Fi 3)*
802.11g
6 to 54
2003
2.4
(Wi-Fi 2)*
802.11a
6 to 54
1999
5
(Wi-Fi 1)*
802.11b
1 to 11
1999
2.4
(Wi-Fi 0)*
802.11
1 to 2
1997
2.4
One way 802.11n and 802.11ac networks achieve superior throughput and speeds by using multiple-input
multiple-output (MIMO) and multi-user MIMO (MU-MIMO), respectively.
MIMO uses multiple antennas for transmission and reception, which results in higher speeds than 802.11a and
802.11g networks, which can only support up to 54 Mbps of throughput.
Index
Wireless N and Wireless AC networks also utilize the 5 GHz frequency band, allowing them to achieve speeds
greater than 54 Mbps.
WPA2 is a wireless encryption standard and can be used with Wireless G, N, AC, or AX.
Lightweight Access Point Protocol (LWAPP) is the name of a protocol that can control multiple Wi-Fi wireless
access points at once. This can reduce the amount of time spent on configuring, monitoring, or
troubleshooting a large network. LWAPP does not affect the speed of a wireless network.
Index
DNS Record Types
A CNAME record is a canonical name or alias name, which associates one domain name as an alias of another (like
beta.diontraining.com and www.diontraining.com could refer to the same website using a CNAME).
An MX record is used for outgoing (SMTP) and incoming (POP3/IMAP) traffic.
An A record associates your domain name with an IPv4 address.
An AAAA record associates your domain name with an IPv6 address.
The DNS text (TXT) record lets a domain administrator enter text into the Domain Name Systems. The TXT record was
originally intended as a place for human-readable notes. However, now it is also possible to put some machine-readable
data into TXT records. TXT records are a key component of several different email authentication methods (SPF, DKIM,
and DMARC) that help an email server determine if a message is from a trusted source.
A DNS service (SRV) record specifies a host and port for specific services such as voice over IP (VoIP), instant messaging,
and others.
A Start of Authority (SOA) resource record indicates which Domain Name Server (DNS) is the best source of information
for the specified domain.
PTR records are used for the Reverse DNS (Domain Name System) lookup. Using the IP address, you can get the
associated domain/hostname. An A record should exist for every PTR record.
Nameserver (NS) records are used to list the authoritative DNS server for a particular domain.
Index
Network Parameters & Delays
Jitter is a network condition that occurs when a time delay in the sending of data packets over a network connection
occurs. Jitter is a big problem for any real-time applications you may be supporting on your networks, like video
conferences, voice-over IP, and virtual desktop infrastructure clients. A jitter is simply a variation in the delay of the
packets, and this can cause some strange side effects, especially for voice and video calls. If you have ever been in a
video conference where someone was speaking and then their voice started speeding up for 5 or 10 seconds, then
returned to normal speed, you have been on the receiving end of their network’s jitter.
Latency is the measure of time that it takes for data to reach its destination across a network. Usually, we measure
network latency as the round-trip time from a workstation to the distant end and back.
Throughput is an actual measure of how much data is successfully transferred from the source to a destination.
Bandwidth is the maximum rate of data transfer across a given network. Now, bandwidth is more of a theoretical
concept that measures how much data could be transferred from a source to a destination under ideal conditions.
Therefore, we often measure throughput, instead of bandwidth, to monitor our network performance.
Crosstalk is defined as an effect caused by the unintentional and undesired transmission (leakage) of a signal
from one cable to another. Abused cables that are stepped/runover repeatedly can suffer from this.
Troubleshooting
Split Horizon is a form of route advertisement that prohibits a router from advertising back a route to the
same interface from which it learned it. This does not affect the issues experienced with the microwave line.
▪
Another way to approach this question is to use the process of elimination: throttling slows down the
speed, and latency slows down speed even further. Split horizon prevents loops, so it only makes sense
that interference is the correct choice since interference can cause drops in connections in many
situations.
DNS Issues
Whenever you have an issue where you can ping the server's IP, but you cannot access it by its domain name,
it has something to do with DNS.
ipconfig /flushdns command provides you with a means to flush and reset the contents of the DNS client
resolver cache: during DNS troubleshooting, if necessary, you can use this procedure to discard
negative cache entries from the cache, as well as any other dynamically added entries.
Resetting the DNS Cache does not eliminate entries that are preloaded from the local Hosts file. To
eliminate those entries from the cache, remove them from the hosts.ini file instead.
Index
Decreased Speeds from bad NIC Drivers
Often, security updates, patches, and upgrades will reconfigure a network card's drivers during a Windows
security update.
▪
▪
If this happens, the system may revert to a more generic version of the driver, decreasing speeds from
1 Gbps to 100 Mbps. The network card's drivers should be rolled back to the previous driver to restore
functionality and correct it.
If there were configuration changes to the DNS or DHCP server, it would limit connectivity completely
instead of simply slowing down the connection.
If the network changed from DHCP to static assignments, the workstations would not get an APIPA address
and would not have connected to the network at a slower speed.
Steady Lights on a Network Interface Card (NIC) indicate that there is no network activity. If it is blinking, this
indicates that data is passing over the NIC to the network.
▪ Even if there were an incorrect TCP/IP configuration or intermittent connectivity, there would be
Blinking Lights to indicate transmission attempts.
Web Servers should be configured to accept requests through HTTP or HTTPS and provide resources back to
requesters
Index
Cloud Computing & Virtualization
Cloud Terminology
Measured Service is a term that IT professionals apply to cloud computing that references services where the
cloud provider measures or monitors the provision of services for various reasons, including billing, effective
use of resources, or overall predictive planning.
Rapid Elasticity is used to describe scalable provisioning or the capability to provide scalable cloud computing
services.
o Rapid elasticity is very critical to meet the fluctuating demands of cloud users.
o The downside of rapid elasticity implementations is that they can cause significant loading of the
system due to the high number of resource allocation and deallocation requests.
o Rapid elasticity can also be a security threat to your organization's data due to data remanences.
On-demand refers to the fact that a consumer can unilaterally provision computing capabilities, such as server
time and network storage, as needed automatically without requiring human interaction with each service
provider.
Resource Pooling refers to the concept that allows a virtual environment to allocate memory and processing
capacity for use by virtual machines.
‘Desktop as a Service’ - DaaS in this exam seems to refer to ‘Desktop as a Service’, which are Virtualized
Desktop Infrastructure (VDI) services.
Community Cloud in computing is a collaborative effort in which infrastructure is shared between several
organizations from a specific community with common concerns, whether managed internally or by a third
party and hosted internally or externally.
o Community Cloud is a hybrid form of private cloud: they are multi-tenant platforms that enable
different organizations to work on a shared platform.
o Community Cloud may be hosted in a data center, owned by one of the tenants, or by a third-party
cloud services provider and can be either on-site or off-site.
Software-Defined Networking is used to create network infrastructure within clouds, example: VCNs.
Thin Clients
▪
A Thin Client is a stateless, fanless desktop terminal that has no hard drive.
o All features typically found on the desktop PC, including applications, sensitive data, memory,
etc., are stored back in the data center when using a thin client, most typically in a VDI or other
environment.
o To set up a thin client, you will first connect it to the network, update its security software, and
then install/configure any applications needed to access the VDI environment.
Index
Virtualization Tech on Intel is called VT and on AMD it’s AMD-V
VM Network Types
Internal, each VM can communicate between the host and the other VMs.
External, the VMs would have internet access.
Private network connection type will create a switch that is usable only by the VMs. The VMs cannot use the
switch to communicate with the host.
Localhost, each VM could only communicate with itself.
Type I & Type II Hypervisors
A Type 2 hypervisor runs on top of an existing operating system.
A Type 1 hypervisor, also known as bare metal, uses a specialized hypervisor OS to run the virtual machines
(such as VMWare's ESXi).
▪
▪
Also known as a virtual machine monitor, is a process that creates and runs virtual machines (VMs).
o A hypervisor allows one host computer to support multiple guest VMs by virtually sharing its
resources, like memory and processing.
To create and provision virtual machines within the Windows 2019 operating system, you can use a
Type II Hypervisor like VMWare or VirtualBox.
Keyboard Video Mouse (KVM) Switch
A KVM switch is used to support a single set of input and output devices controlling several PCs. A KVM is
typically used with servers but 2- port versions allow a single keyboard, mouse, and display to be used with
two PCs. Generally, a single KVM installed in each server rack allows the administrator to quickly switch
between physical servers within the rack using the same keyboard, mouse, and monitor.
Index
Printers & Projectors
Laser Printer Components (FSD-DTPT)
Fuser Assembly is the component in a laser printer that fixes toner to media. This is typically a combination of
a heat and pressure roller, though non-contact flash fusing using xenon lamps is found on some high-end
printers. When printing with a laser printer, the paper passes through rollers in the fuser assembly, where
temperatures up to 801 F (427 C) and pressure are used to bond the toner to the paper permanently.
Separation Pad is the component in a laser printer that acts as a stationary pad in the paper tray to push the
stack of paper backward to allow only a single sheet to be fed into the printer.
Drum Unit is the component that applies toner to the paper & the fuser subsequently fuses it to the paper. If
the drum unit is not being properly charged by the corona wire, ghost prints (repeated images/text) can
become a problem.
Duplexing Assembly is a component that enables a printer or scanner to use both sides of a page
automatically.
Transfer Belt is the component in a color laser printer that combines the 4 colors before printing it to the
paper in one pass.
Pickup Roller is the component in a laser printer that turns above a stack of paper to feed a sheet into the feed
roller. Replace the rollers if a crinkling sound is heard and prints are at an angle!
Transfer Roller is the component in a laser printer that applies an electric charge to the paper to attract toner
from the photoconductor during the imaging process. Clean it if streaks are seen on printouts.
Share a Printer
▪
▪
The simplest and most cost-efficient way to share a printer is via to allow sharing via the localhost
across everyone on the network.
o While this costs nothing to establish and requires no additional hardware, it does require that
the localhost remain on 24 hours a day so that others can print at any time.
o If you are willing to spend a little money though, you can purchase a wireless print server or a
new network-capable printer instead.
The BEST solution would be to use a wireless print server and to connect the printer to it via USB. The
wireless print server can then receive print jobs directly from all network users. It is not recommended
that the technician create a share on a manager's computer or set the printer configuration to the
manager's IP address since all print jobs would fail anytime the manager shuts down or restarts their
computer.
Index
Printer Types
3-D Printers use a filament to create the objects being printed:
▪ A 3D-printing Filament is a thermoplastic feedstock for fused deposition modeling by 3D printers.
▪ There are many types of filament available with different properties, requiring different temperatures
to print the final product or object.
▪ On the exam, you should be thinking about a 3D printer anytime you see the word filament.
Inkjet Printers use an Inkjet Cartridge
Laser Printers use Toner
DCPS (DC Power Supply/Source) of a Laser Printer is used to convert high voltage AC into lower voltage DC for the
printer. The DCPS converts 115VAC or 220VAC power into +5 VDC and -5 VDC for use by the printer's logic
board, and +24 VDC to power the motors that feed the paper through the printing path.
A symptom of low toner is faded or faint colors in your printed papers. Replace the toner if prints are faded!
Impact / Dot-Matrix Printers use Ribbons
▪ An Impact / Dot-Matrix Printer is an older type of printer that works by pressing a ribbon of ink onto
the top sheet of paper using a series of dots.
▪ An impact printer operates the same way as an old-fashioned typewriter. It uses a film-like ribbon that
sits inside between the paper and print head.
Thermal Printers use Ribbons or Special Thermal Paper
Keep in mind that USB Type-B ports are the most common USB connectors on the backs of printers!
Printers: Collate vs Duplex
Collating creates consistent, logical sets from multiple parts, such as printing a series of pages in a report like pages 1, 2,
3 before printing the second copy.
Duplex printing is a feature of some computer printers, multi-function printers (MFPs), and copy machines that allow the
printing of a sheet of paper on both sides automatically. With duplex printing, information is printed on the front side of
a piece of paper, and then the paper is automatically fed back through the printer to print the information on the
backside of the paper.
Steps in a Laser Printer’s Imaging Process (PCEDTFC)
The proper sequence of events when printing a document using a laser printer is processing, charging, exposing,
developing, transferring, fusing, and cleaning. This is referred to as the imaging process.
Index
Troubleshooting
Dust on Printed Pages
Q: The large multi-function network printer has recently begun to print pages that appear to have a dust-like coating
when handled by the users. Which of the following components should be replaced based on this description?
A: Fuser
The printer passes the paper through the fuser, a pair of heated rollers. As the paper passes through these rollers, the
loose toner powder melts, fusing with the paper's fibers. The fuser rolls the paper to the output tray, and you have your
finished page. The fuser also heats the paper itself, of course, which is why pages are always hot when they come out of
a laser printer or photocopier. If the paper feels dusty or the toner doesn't adhere to the printer, this usually indicates a
failing fuser that needs to be replaced.
No Prints
Apparently if a printer worked fine yesterday but refuses to print today, check the print server queue FIRST, even before
verifying whether the printer is online!
Projectors Keystone & Double Images
Keystone Effect occurs when the top of a projected image is wider or narrower than the bottom of the image.
This creates a trapezoid instead of a rectangular image and leads to distortion. To fix the keystone effect in an
image, you need to adjust the keystone setting in the projector.
When dealing with Flickering Images on a Projector, check the display cables first before the power cables.
Projector Too Dim?
Try increasing contrast FRIST. NOT directly replacing the bulb.
Smeared prints with a laser printer: Increase the temperature of the fuser element!
Left-to-Right Faded Print on an Impact/Dot-Matrix Printer
An impact printer has teeth along the paper's edges that pull the paper along a tractor as it prints. This moves
the paper up one line at a time. The print head moves from left to right across the page, impacting the print
head through the ribbon to mark the paper.
If the ribbon advance mechanism is defective, the ribbon will not advance as the print head goes across the
page, leading to a lightening of the ink being marked on the paper.
If the printer ribbon itself were worn out, it would be lighter in color as you went down the page (not from left
to right).
Index
Page Description Languages for Printers
Printer Control Language (PCL) is a page description language used to tell printers how to properly layout and print
the contents of a document on a page. PCL is a common printing language that is supported by many different printer
manufacturers.
PostScript (PS) is the page description language used in the electronic publishing and desktop publishing business. PCL
is faster to print than PS. PS is slower but produces higher quality outputs.
Apple Bonjour
Apple’s zero-configuration networking protocol automates certain aspects of network configuration, and is
used to find available printers on a network.
o The protocol enables devices connected to the local area network to discover and connect
automatically.
o Businesses can use Bonjour to make the sharing of files and devices easier.
o The technology works with wired and wireless LANs.
o After enabling Bonjour on a workstation, other computers on the network can detect and
install printers or scanners attached to the workstation or access files from shared folders.
Basically when in doubt about Apple tech questions, select the most pretentious sounding name and option.
Also, should a MacBook not print, install the print drivers for MacOS on the print server first. Don’t select
“Enable Bonjour” as a de-facto answer for this on the test!
Index
Mobile Devices & IoT
Cellular Technology
3G Cellular Technology is made up of two different technologies:
HSPA+ (Evolved High-Speed Packet Access) and EV-DO (Evolution-Data Optimized)
o HSPA+ has a theoretical download speed of 168 Mbps and a theoretical upload speed of 34 Mbps. In
the real world, though, HSPA+ normally reaches speeds around 20 Mbps.
o EV-DO is a 3G standard used for CDMA cellular networks and can support up to 3.1 Mbps downloads.
CDMA was only popular in the United States with a few providers (Verizon and Sprint). Most of the world uses
GSM instead.
4G Cellular Technology is made up of
LTE and LTA-A:
o LTE has a theoretical speed of 150 Mbps and a real-world speed of around 20 Mbps. LTE Advanced
(LTE-A) has a theoretical speed of 300 Mbps and a real-world speed of around 40 Mbps.
5G Cellular Technology is made up of three different types: low-band, mid-band, and high-band mmWave
(millimeter wave) technology.
Carrier Roaming
▪
▪
▪
The PRI and PRL must be updated and referenced when traveling.
Preferred Roaming Index (PRI) is an index that works with the PRL to provide the best
data/voice quality to a phone while roaming.
Preferred Roaming List (PRL) is a database built by CDMA service carriers to indicate which radio
bands should be used when connecting to a cell tower.
The baseband is the embedded operating system in the firmware of a smartphone or other cellular
device.
o The firmware is a set of software instructions stored semi-permanently (embedded) on a
hardware device.
o Modern types of firmware are stored in flash memory and can be updated more easily than
legacy programmable Read-Only Memory (ROM) types.
The baseband and firmware would not be updated or changed based on your location. The baseband is
changed or updated when a security update is needed.
Index
Mobile Location Services
A mobile device can use its internal GPS, cellular, Bluetooth, or Wi-Fi radios to identify its location:
GPS (Global Positioning System)
▪ A GPS device is used to determine a receiver's position on the Earth based on information received
from 24 GPS satellites, which operate in a constellation in Medium Earth Orbit (MEO).
o The receiver must have a line-of-sight to four of the GPS satellites continuously to accurately
determine its position on the earth (latitude, longitude, and altitude).
o The device’s GPS receiver can provide an accurate location up to 10 meters.
Cellular Radios
▪ Can provide an approximate location based upon the triangulation of your position between different
cellular towers.
Bluetooth
▪ Can be used within a building to provide an accurate of the device within 3-4 meters.
Wi-Fi Positioning Systems
▪ Use the signal strength or angle of arrival of a signal to determine the device’s location within 1-4
meters.
Internal Positioning System (IPS)
▪ The use of Bluetooth and Wi-Fi to determine the device’s location is known as an IPS
Q: Which of the following technologies is often used indoors by companies to locate a shopper's position in a
store and provide them time-sensitive offers or discounts?
A: Bluetooth.
Bluetooth can be used within a building to provide an accurate of the device within 3-4 meters. Bluetooth
location services are often used to identify where in a store a customer is located and present them with
targeted offers. For example, if the store identified that you were in the frozen foods section, they might
send you a push notification offering you a discount on a pint of ice cream. Wi-Fi positioning systems use the
signal strength or angle of arrival of a signal to determine the device’s location within 1-4 meters.
Tethering vs Hotspot
As a hotspot, your mobile phone acts just like a Wi-Fi router and people can connect to it and access the internet using
your mobile data.
With tethering, a phone's data is shared with other devices but through different means such as via Bluetooth or a USB
cable. This is referred to as Bluetooth tethering or USB Tethering, respectively. Both fall under “Tethering”, which is a
generic term.
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‘Hotspot’ and ‘Tethering’ are very similar, but a few notable differences are that tethering is more secure as compared
to hotspot and it can be used for different things as well like sharing files between devices.
Hotspot = Your mobile acts as a wireless AP, and people can connect to it.
Tethering = A USB cable or Bluetooth is used to connect a PC to the internet via your phone. "Tether" = cable.
Q: Your cellular carrier allows you to turn on a feature on your smartphone so that you can share its internet
connection with other devices close to your smartphone. If you wanted to share the internet connection with multiple
devices simultaneously, which feature would you enable?
A: Mobile Hotspot
Q: Jason is teaching a CompTIA course at a large company, but they do not allow non-employees to connect to their
network. Since Jason needs the Internet for an in-class demonstration, he connects his laptop to his iPhone using a
USB cable. He essentially connects to the Internet using the smartphone as a modem. Which of the following terms
best describes this configuration?
A: Tethering
Flickering mobile screens implies a backlight issue as per the official study guide
Internet of Things (IoT)
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Supervisory Control and Data Acquisition (SCADA) systems, Industrial Control Systems (ICS), internetconnected televisions, thermostats, and many other things are examples of devices classified as the
Internet of Things (IoT).
o A laptop would be better classified as a computer or host than part of the Internet of Things.
o Internet of things (IoT) is a system of interrelated computing devices, mechanical and digital
machines provided with unique identifiers (UIDs), and the ability to transfer data over a
network without requiring human-to-human or human-to-computer interaction.
Home Automation
Zigbee is an open-source (Unlike Z-Wave, which is proprietary) wireless communication protocol used
for home automation.
o Zigbee uses the 2.4 GHz frequency band. This higher frequency allows more data bandwidth at
the expense of range than Z-Wave and the greater risk of interference from other 2.4 GHz radio
communications
o Zigbee supports more overall devices within a single network (65,000 compared to 232 for Zwave), and there is no hop limit for communication between devices.
Z-wave is a low-power wireless communications protocol used primarily for home automation. Z-wave
uses radio frequencies in the 800 MHz and 900 MHz frequency ranges.
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Troubleshooting Software
"Pinwheel of Death” is used to indicate an error on a Mac (OS X) system, like the BSOD used in Windows. The
pinwheel appears as an endlessly spinning rainbow mouse pointer displayed on the screen. This usually occurs
due to a memory failure or memory corruption in the system.
The "OS Not Found" Error at boot time is an indication that the MBR (Master Boot Record) or GPT (Globally
Unique ID Partition Table) is corrupted or faulty.
If this occurs, you should reboot into the Windows recovery mode and use the following command to fix the
GPT:
'bootrec /fixboot'
To troubleshoot the failed boot, you must reboot the computer and enter into recovery mode:
o In Windows 10, you will need to boot from the installation disc, select "Repair your computer",
and then enter the command-line interface (CLI).
o From the CLI, enter the command
"bootrec /fixmbr"
o to repair the master boot record.
o Once completed, reboot the computer, and allow it to load into Windows.
"No Boot Device Available" is an error message that indicates the workstation is not recognizing the hard
drive.
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If the error message were
"Operating system not found" or
"NTLDR not found" this would indicate that the hard drive was recognized but that the Windows OS
was not installed properly.
o NTLDR is an abbreviation from NT Loader and is the boot loader for all releases of the Windows
NT OS from 1993.
"BIOS ROM checksum error" would indicate an issue with the BIOS, not the hard drive.
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Always Backup First!
You should always ensure that a recent backup of all of the client's important and critical files has been created before
making any changes to the computer. In fact, even choose this option over “Make OS restore point” when asked what’s
to be done FIRST! After all, it is easy to replace hardware if you break the computer, but the client's personal files may be
irreplaceable.
Shadow Copy (also known as Volume Snapshot Service, Volume Shadow Copy Service or VSS) is a technology included
in Microsoft Windows that can create backup copies or snapshots of computer files or volumes, even when they are in
use. It is implemented as a Windows service called the Volume Shadow Copy service. A software VSS provider service is
also included as part of Windows to be used by Windows applications. Shadow Copy technology requires either the
Windows NTFS or ReFS filesystems in order to create and store shadow copies. Shadow Copies can be created on local
and external (removable or network) volumes by any Windows component that uses this technology, such as when
creating a scheduled Windows Backup or automatic System Restore point.
F12 is the most commonly used key used to enter the BIOS / UEFI boot order menu.
F11 during the boot is used to boot into recovery mode on a Windows workstation.
F8 is used to invoke the Advanced Boot Options menu.
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Cybersecurity
Unified Threat Management (UTM)
An UTM appliance enforces a variety of security-related measures, combining the work of a firewall, malware scanner,
and intrusion detection/prevention. A UTM centralizes the threat management service, providing simpler configuration
and reporting than isolated applications spread across several servers or devices.
Preboot Execution Environment (PXE)
The Preboot Execution Environment (PXE) is an industry-standard client/server interface that allows networked
computers that are not yet loaded with an operating system to be configured and booted remotely by an administrator.
Secure boot is a security system offered by UEFI that is designed to prevent a computer from being hijacked by
malware.
Intrusion Prevention System (IPS) and Intrusion Detection System (IDS)
An Intrusion Prevention System (IPS) is a form of network security that detects and prevents identified
threats. Intrusion prevention systems continuously monitor your network, looking for possible malicious
incidents, and capturing information about them. An IPS can block malicious network traffic, unlike an
Intrusion Detection System (IDS), which can only log them.
Authentication, Authorization, and Accounting (AAA) Server
An AAA server is a server use to identify (authenticate), approve (authorize), and keep track of (account for)
users and their actions. AAA servers can also be classified based on the protocol they use, such as a
RADIUS Server or
TACACS+ Server
MDM is for remote device management.
MAM (Mobile Appln Management) is for remote enterprise app management!
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SPF, DKIM & DMARC
Sender Policy Framework (SPF) uses a DNS record published by an organization hosting an email service. The SPF
record identifies the hosts authorized to send emails from that domain, and there must be only one per domain. SPF
does not provide a cryptographic authentication mechanism like DKIM does, though.
SPF is an email authentication method designed to detect forging sender addresses during the delivery of the email. SPF
alone, though, is limited to detecting a forged sender claim in the envelope of the email, which is used when the mail
gets bounced. Only in combination with DMARC can it be used to detect the forging of the visible sender in emails (email
spoofing), a technique often used in phishing and email spam.
SPF allows the receiving mail server to check during mail delivery that a mail claiming to come from a specific domain is
submitted by an IP address authorized by that domain's administrators. The list of authorized sending hosts and IP
addresses for a domain is published in the DNS records for that domain.
DomainKeys Identified Mail (DKIM) provides a cryptographic authentication mechanism. This can replace or
supplement SPF. To configure DKIM, the organization uploads a public key as a TXT record in the DNS server.
DKIM is an email authentication method designed to detect forged sender addresses in email (email spoofing), a
technique often used in phishing and email spam.
DKIM allows the receiver to check that an email claimed to have come from a specific domain was indeed authorized by
the owner of that domain. It achieves this by affixing a digital signature, linked to a domain name, to each outgoing
email message. The recipient system can verify this by looking up the sender's public key published in the DNS.
The Domain-Based Message Authentication, Reporting, and Conformance (DMARC) Framework can ensure that
SPF and DKIM are being utilized effectively. DMARC relies on DKIM for the cryptographic authentication mechanism.
DMARC is an email authentication protocol. It is designed to give email domain owners the ability to protect their
domain from unauthorized use, commonly known as email spoofing.
Once the DMARC DNS entry is published, any receiving email server can authenticate the incoming email based on the
instructions published by the domain owner within the DNS entry. If the email passes the authentication, it will be
delivered and can be trusted. If the email fails the check, depending on the instructions held within the DMARC record
the email could be delivered, quarantined, or rejected. For example, one email forwarding service delivers the mail, but
as "From: no-reply@<forwarding service>".
Q: Which of the following provides a cryptographic authentication mechanism to positively identify an organization as
the authorized sender of email for a particular domain name?
A: DKIM
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