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CNET 201/205 - CompTIA A+ - Chapters 1-5 MIDTERM NOTES
Chapter 1 – Taking a Computer Apart and Putting it Back Together
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Port
Electrostatic Discharge (ESD) is a name for static electricity, which can damage chips, destroy
motherboards, or harm you. An ESD strap dissipates any ESD between you and a system
Computer cases are sometimes called chassis; houses the PSU, mobo, PCU, memory modules,
expansion cards, hard drives, optical drives, and other drives
o Tower cases sit UPRIGHT
o Desktop cases lies FLAT
Description
VGA (Video Graphics Array); DB-15; HD15; 15-pin female transmits analog video
DVI (Digital Video Interface) transmits digital or analog; 3 types exist (DVI, DVI-D,
DVI-I)
HDMI; transmits digital video and audio
DisplayPort; digital and audio; replacing VGA and DVI, was thought to replace HDMI
Thunderbolt 3; transmits video, data, and power; up to 6 peripherals can use the
same port
Audio ports; can transmit analog or digital audio in/out
SPDIF sound port; external home theatre audio, digital audio output; when
connected to a fiber-optic cable, is called an optical connector
USB (Universal Serial Bus); multiple purpose; can be USB, USB 2.0, or Super-Speed
3.0
eSATA; used by external hard drives generally
PS/2; purple = keyboard, green = mouse
Serial Port/DB9 port; mostly replaced by USB; sometimes seen on a router for
technicians for monitoring/using
Modem port; RJ-11; used to connect dial-up phone lines; right port in image is an
RJ-11 port and left is a network port
Network port; RJ-45; Ethernet port; connects to a wired network, Fast Ethernet
ports run at 100 Mbps, Gigabit Ethernet runs at 1000 Mbps (1 Gbps)
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Loopback plugs are used to test network ports or other devices to ensure the port is working,
can also test the throughput or speed of the port (can also do with USB loopbacks for USB ports)
Steps to open a computer case:
o Back up important data
o Have a container for loose
o Power down and unplug
screws
o Drain the PSU by holding the
o Open the case cover
power button for 3 seconds
o Clip your ESD to the side of the
case
Main internal components of a computer:
 Motherboard (main board, system board): largest and most important circuit board;
hosts a socket to host the CPU
 Central Processing Unit (CPU, processor): processes most of the data and instructions
for the entire system
 Heat sink: consists of metal fins that draw heat away from a component
 A fan and heatsink together are called the processor cooler
 Expansion cards (adapter card): a circuit board that provides more ports than those
provided by the mother board
 Memory slots (DIMM): holds memory modules
 RAM (random access memory): temporary storage for data and instructions as
they are being processed by the CPU
 HDDs: permanent storage to hold data and programs
 PSU: receives and converts the current; most have a dual-voltage selector switch to
switch from 115V (US) to 220V (EU)
Form factors are the standards that describe the size, shape, screw hole positions, and major
features of these interconnected components
 Assures mobo, PSU, attachment holes for mobo and ports, allows for wires for
switches/lights in front of the case, and anchoring holes
 ATX (advanced tech extended): most common, originally developed by Intel
 microATX (mATX): reduces the total cost of the system by reducing the number of
expansion slots on the board; reduces power supplies and allows for a smaller case
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20-pin P1 connector: main mobo power connector used in early ATX systems
24-pin P1: main mobo power connector used today
20+4 pin: has four pins removed so it can fit into a 20-pin P1 mobo connector if
needed
4-pin 12V connector: aux mobo connector, used for extra 12V power to the processor
8-pin 12V connector: aux mobo connector used for extra 12V power to the processor,
providing more power than the older 4-pin aux connector
4-pin Molex connector: used for older IDE drives, some newer SATA drives, and for
extra video card power. Provides +5V and +12V
SATA power connector: used for SATA drives, 15 pins, provides +3.3V, +5V, and +12V,
although +3.3V seldom used
PCIe 6-pin connector: provides extra +12V for high end video cards using PCIe
PCIe 8-pin connector: provides extra +12V for high-end video cards using PCIe
PCIe 6/8-pin connector: used by high end video cards using PCIe x16 slots, can
accommodate a 6-hole or 8-hole port
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A PSU that provides a 4-pin 12V power cord is called an ATX12V Power Supply
o Later boards replaced the 4-pin 12V with an 8-pin aux connector for more amps for the
processor
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If fine traces on the mobo touch the case, a short would result; plastic or metal pegs that
separate the board from the case are called spacers or standoffs and are used to prevent this
POST diagnostic cards help report computer errors after you first turn on a computer but before
the OS is launched
o The POST (Power on self-test) is a series of tests performed by the startup BIOS/UEFI
when you first power on a computer
Mobos use firmware, which has to do with the programs and data stored on the board
o Consists of the older BIOS (Basic Input/Output System) and the newer UEFI (Unified
Extensible Firmware Interface)
o Manages essential devices before the OS is launched, starting the computer, and
managing mobo settings
o UEFI allows for a secure boot, which prevents rogue malware of OS hijacks on the
system
o The firmware chip contains the BIOS/UEFI, flash ROM, and CMOS RAM. CMOS RAM is
powered by the coin battery located near the chip, generally a CR2032
A Power Supply Tester is used to measure the output of each connector coming from the PSU
A Multimeter can measure several aspects of electricity in a variety of devices; can measure
voltage, continuity, or match pins to a cable
The front panel header of a motherboard has these general labels:
o Power SW: controls mobo power, must be connected for PC power
o HDD LED: controls drive activity light when the HDD is in use
o Power LED+ / Power LED- : positive and negative LED controls for the power light
o Reset SW: Switch used to reboot
Laptops can use a docking stations to provide ports to allow a laptop to easy connect to
different peripheral devices
A port replicator provides ports to allow a laptop to connect to more peripheral devices that is
accessible on the mobo
Laptop replacement parts cost more than desktop parts because their components are designed
to be more compact and stand up to travel
An example of diagnostic software is PC-Doctor to help test components
In a laptop, some ribbon cables are ZIF connectors (zero insertion force) and some have plastic
screws that are only meant to be used once
For laptops with built-in batteries, put the laptop into Ship mode (generally accomplished using
Fn + S + V) to disable the battery stop power supply to components
Laptops use SO-DIMMS (small outline dual inline memory modules) for more compact RAM
and mini PCI Express cards
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Chapter 2 – All About Motherboards
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When putting a computer together, you start by deciding with processor and mobo you will use
o When selecting a mobo, pay attention to form factor, processor socket, chipset,
expansion slots, and ports
The three form factors are ATX, microATX (mATX), and min-ITX (mITX; small form factor)
o SFF’s are often used in low-end computers or home theatre systems. Use Celeron and
Atom processors
o An ATX is rectangular, a mATX is square, and the mITX is the smaller square
Chipset: set of chips on the mobo that work with the PCU to control the memory, buses, and
some peripherals
Socket: rectangular with pins or pads to connect the PCU to the mobo and hold it the PCU in
place
o Chipset and socket determine which PSU a board can use
Intel Chipsets:
o Coffee Lake: 8th gen, use LGA1151 v2 socket, uses DDR4 memory, and falls into Coffee
Lake H-Series or Kaby Lake Refresh
o Kaby Lake: 7th gen desktop processors and chipsets, use LGA1151 v1 socket
o Skylake: 6th gen, use LGA1151 socket, use DDR4 memory, can use low voltage DDR3
o Broadwell and Haswell: 5th and 4th gen respectively, work with the LGA1150 and
LGA2011 sockets
First four digits in an Intel processor dictate the generation (ex. Core i5-7500 is 7th gen)
Intel uses LGA (land grid array) sockets
AMD Chipsets:
o TR4 (Threadripper 4): LGA, uses AMD X399, use the Ryzen CPUs
o AM4: Used with AMD Ryzen and Athlon PSUs, include the A300, B300, and X300.
Socket has 1331 pins and uses a pin grid array (PGA), which means the 1331 pins fit into
1331 socket holes
o AM3+ / AM3: Used with AMD Piledriver and Bulldozer PCUs and the 9-series chipsets,
used in high-end gaming systems and these are interchangeable socket-wise
o FM2+: Older PGA socket used with AMB Athlon, Steamroller, and Excavating CPUs and
A-series chipsets
If you install a processor on a mobo that can fit the socket but has the wrong chipset, you can
damage both the mobo and CPU
Traces: circuits that enable data, instruction, timing signals, and power to move from
component to component on the board
o These pathways and the protocol methods used for transmission are called a bus
PCI Express (PCIe) comes in four different slot sizes: x1, x4, x8, x16
o Each slot size indicates the number of lanes available for data transmission
o You can connect a shorter card into a larger slot and it will only use the slots connected
o v4 PCIe is the fastest
o A GPU in a x16 might require as much as 450 watts, and a typical PCIe x16 slot provides
75 watts, so mobo’s generally have power connectors near this slot
 Might be a 6+2 connector 150W, a 4-pin molex connector, or a SATA connector
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Riser cards provide a slot for an expansion card installed parallel to the mobo
Onboard ports: ports directly on the mobo
Headers: group of pins sticking up on the board
M.2 connector uses PCIe, USB, or SATA interface to connect a mini addon card; commonly used
for wireless cards and SSDs
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IDE (integrated drive electronics) was used to interface storage devices with mobos, was a 40pin connector
UEFI is required for 2-TB drives
o Master Boot Record (MBR) allows for four partitions and is limited to 2-TB drives
o GUID Partition Table (GPT) allows for any size of drive and can have up to 128
partitions
o For backward compatibility, UEFI can boot from a MBR hard drive and provide
Compatibility Support Mode (CSM) that use BIOS
S.M.A.R.T. (Self-Monitor Analysis and Reporting) monitors statistics reported by a hard drive
and can predict when the drive is about to fail
Platform Key (PK): Digital signature that belongs to the mobo or computer manufacturer to
authorize secure boot enabling/disabling and updating the KEK database
Power-on Passwords prevent unauthorized access to the computer or BIOS/UEFI utility
o If supervisor and user passwords are both set, you can lock down a computer from
unauthorized access
LoJack and Computrace Agent are embedded in firmware to protect against theft; helps locate
it through internet signal and can give remote commands to lock it
Hard drive passwords do not encrypt all of the data, only a few organizational sectors and are
not as secure as drive encryption8
Mobos have TPM (Trusted Platform Module) chip and use Bitlocker Encryption to prevent
unauthorized access; the Bitlocker relies on the TPM key in the mobo to be unlocked
o If the mobo fails, you will need a backup copy of the startup key to access the data on
the drive
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Device drivers are small programs on the board drive that an OS uses to communicate with a
specific hardware device
Flashing BIOS/UEFI – upgrading or refreshing the programming and data on the firmware chip
o Might do this if: system hangs during boot, mobo functions have stopped working or
cause problems, errors when trying to install new OS, incorporate new features or
component to the board
Back flash: reverting to an earlier BIOS/UEFI version
Jumpers: two small ports or metal pins used to hold configuration information
o Jumpers 1 and 2 closed – normal booting
o Jumpers 2 and 3 closed – BIOS/EUFI setup can be cleared on the next boot
o No jumpers closed – BIOS/UEFI recovers itself on the next boot from a failed update
CMOS RAM: small amount of memory stored on the mobo that retains data even when the
computer is turned off due to the CMOS battery
o If the CMOS battery is disconnected or fails, setup information is lost
o Indication that CMOS battery is weak is system date and time are wrong after power has
been disconnected to the PC
o CMOS battery considered FRU
Chapter 3 – Support Processors and Upgrading Memory
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Features that affect CPU performance and compatibility with mobos:
o Frequency: the speed the processor operates measured in GHz
o Lithography: average space between transistors printed on the surface of the silicon
chip, ranges from 14nm to 35nm and the lower the better
o Socket and chipset
o Multiprocessing: using two processing units (known as ALUs) installed within a single
processor; can execute two instructions at once
o Multithreading: each processor or core processes two threads at the same time; there
are two logical processors for each physical processor or core
 Intel refers to it as Hyper-Threading and AMD calls it HyperTransport
o Multicore Processing: multiple processors installed in the same housing; might contain
up to 8 cores
o Dual processors: a server mobo might have two processor sockets called dual
processors or multiprocessor platforms
o Memory cache: amount of memory within the processor, all have some memory on the
chip called a die, also referred to as Level 1 Cache (L1 Cache). Can have 4 to 12 MB and
up to L3 cache
o If it can support DDR, DDR2, DDR3, or DDR4
Some Intel processors use Centrino technology, where the processor, chipset, and wireless
network are all connected as a unit for laptops to improve performance (or silver and gold for
laptops)
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High end servers often use Xeon, Xeon Phi, and Itanium
o These are more expensive because they are more stable and error-free than desktop
processors
When installing the processor, make sure that cables and cords don’t obstruct fans or airflow
near the processor or video card
If power comes on but the system fails, the processor is likely not seated or some power cord
has not yet been connected
If the system comes up and begins the boot process but suddenly turns off, the processor is
likely overheating
RAM has three main memory modules currently:
o DDR4: 288-pin and the fastest with lower voltage requirements, can support quad,
dual, or single and has one notch near the centre
o DDR3: 240-pin can support quad, triple, dual, or single channels, has an offset notch
farther from the centre than DDR2
o DDR2: 240-pin can support dual or single, has one notch near the centre
SIMM is older tech that has pins only on one side
DIMM speeds are measured in MHz or PC rating
o PC Rating is a measure of the total bandwith (MB/s) of data moving between the
module and CPU; to calculate, multiply speed by 8 because DIMM has an 8-byte or 64bit data path
DIMM in servers is generally ECC (error correcting code): ECC compares bits written to what is
later read from the module, and can detect and correct an error in a single bit, if there are 2
errors in 2 bits it can detect it but cannot correct it
o Cannot mix ECC and non-ECC RAM
Older SIMMS and DIMMS used parity
o A ninth bit was stored with every 8 bits to make the bits either odd or even, if it reads
back and if the bits were not odd for odd parity, it would provide a parity error
o Parity Error 1 – mobo, Parity Error 2 – expansion card
Buffers increase memory performance in servers; cannot mix buffered with unbuffered
CAS Latency refers to the number of clock cycles to write or read a column of data; lower values
are better. CL 8 > CL 9, for example
o Sometimes given in a string of timing numbers, such as 5-5-5-15; where the first is the
CAS
Laptops use DDR4, DDR3L, DDR3, or DDR2 SO-DIMM memory:
o DDR4: 2.74” 260-pin, notch is offset from the center
o DDR3: 2.66” 204-pin, notch offset from centre
 DDR3L: uses less power than a normal DDR3
o DDR2 SDRAM: 2.66” 200-pin, notch is near the side of the module
Adding more RAM might solve slow performance, applications refusing to load, or an unstable
system
SPD (serial presence detect) is a DIMM technology that declares the module’s size, speed,
voltage, and data path width to the system
If you mix memory speeds, the modules will perform at the slowest speed
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Chapter 4 – Supporting the Power System and Troubleshooting Computers
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There are several ways to keep a system cool: keep the case closed, clean the inside, and move
the computer if in a hot or dusty area
Cooler: sits on top of the CPU and consists of a fan and a heat sink
Heatsink: made of metal that draws heat away from the processor into the fins
o can be made of aluminum or copper, copper is more expensive but a better conductor
If a fan has a 4-pin header, it can support pulse-width modulation (PWM) to control fan speed to
reduce overall noise
When replacing a PSU, pay attention to the capacity for the +12V rail (used to describe each
circuit provided by the PSU)
Video cards draw the most power and draw from the +12V output
The PSU should be rated about 30% higher than expected needs
Can view logs about the system using Event Viewer
Some companies use expert systems, which is a software designed to help solve problems using
databased of known facts and rules to simulate human experts’ reasoning and decision making
Possible Symptoms or Error Messages and their Causes
System shuts down unexpectedly
System shuts down unexpectedly and
starts back up
System locks up with an error message
on a blue screen
System locks up with an error message
on a black screen
System freezes or locks up without an
error message
POST code beeps
No power
Blank screen when you first power up
the computer, and no noise or indicator
lights
Blank screen when you first power up,
and you can hear the fans spinning and
see indicator lights
BIOS/UEFI loses its time and date
settings: “CMOS battery low” error
System reports less memory than you
know is installed
System attempts to boot to the wrong
boot device
Fans spin, but no power to other devices
Smoke or burning smell
Overheating, faulty RAM, mobo or CPU failure
Overheating (processor thermal trip error)
Problems with devices, device drivers, or
corrupted OS installation
Error at POST
Application not responding
1 or no beeps = good, more than that, check
mobo website
Check outlet, check on button, dual-voltage,
PSU connectors, and PSU integrity
Likely electrical if power is getting to the PC
Troubleshoot video subsystem
Replace CMOS battery
RAM not seated or has failed
Change boot priority
Check PSU, check voltage outputs
Serious electrical issue, unplug immediately
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Loud whining noise
Clicking noise
Intermittent device failures
Distended capacitors
Error appears during boot: Intruder
detection error
Error appears during boot: Overclocking
failed. Please enter setup to reconfigure
your system
Possible error messages:
No boot device available
Hard drive not found
Fixed disk error
Invalid boot disk
Inaccessible boot device or drive
Invalid drive specification
Possible error messages:
Missing operating system
Error loading operating system
Continuous reboots
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PSU or failing hard drive, might be a short
HDD is failing, replace ASAP
Overheating, failing RAM/mobo/CPU/HDD
Replace mobo
Computer case was opened, suspect security
breach
Discontinue OC, can occur if PSU is failing
Did not find a device to load, ensure proper
booty priority
Windows programs corrupted or missing
Press the key combo to get into BIOS/EUFI, if
can’t then it may be an OS update issue – might
need to do a clean reinstall
If a system overheats, turn it off for at least 30 minutes before trying to power it up again and
check the temperatures upon reboot
o If there is a significant difference from time of boot to 10 minutes after, this is an
overheating problem
Laptops are powered by an AC adapter and/or battery pack that uses lithium ion; most AC
adapters can auto-switch from 110V to 220V AC power
Chapter 5 – Supporting Hard Drives and Other Storage Devices
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Hard drives are rated by its physical size, capacity, speed, internal tech, and interface standards
Magnetic hard drives have a read/write head, and the spindle rotates at 5400, 7200, 10,00 or
15,000 RPM; faster spindles = better performance
o Data is organized in concentric circles called tracks that are divided into sectors
o Form factors are 3.5” for desktops, 2.5” for laptops; 1.8” exist for low-end laptops and
MP3 players
Solid state drives has no moving parts and are built using NVRAM; it does not lose its data even
after the device is turned off
o Memory inside a SSD is called NAND flash memory
o Flash memory is expensive, so SSDs are more expensive than HDDs; however they are
faster, more reliable, last longer, and use less power
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Form factors are 2.5” in desktops and laptops, M.2 SSD that uses the M.2 mobo slot, or
a PCIe SSD expansion card that uses NVMe
Hybrid hard drives exist and are known as H-HDD or SSHD; the magnetic drive houses data with
the flash component buffers to improve drive performance
Before HDDs leave a factory, sector markings are written to it in a process known as low-level
formatting. The firmware, BIOS/UEFI on the mobo, and OS use a simple sequential numbering
system called logical block addressing to address these sectors
o The size of each block and the total number of blocks determine the drive capacity; HDDs
are generally larger in capacity than SSDs
IDE (integrated drive electronics) connectors followed the PATA standard and produced 40-pin
connector cables up to a maximum length of 18”
SCSI (small computer system interface) was used for high end work stations and used a PCIe slot
to provide an external connector for external SCSI devices (printers) and internal devices (drives);
they were 68-pin ribbon cables
SATA interfaces can be hot-swappable, meaning you can swap them while the system is running.
They are more expensive and generally in servers or network storage devices
NVMe (Non-Volatile Memory express) standards are only used by SSDs; they use the fastest x4
PCIe
o Might be used for a PCIe expansion card, a U2 slot (2.5” SSD advertised as a PCIe drive,
U.2 drive, or NVMe SSD), or M.2 port and M.2 ports are more common that U2 ports
To get the best system performance, mobo and drive must support the same interface standard,
otherwise they will use the slowest standard or the drive will not work
Sometimes SATA drives have jumpers, but should not change them as they were set by the
manufacturer
SATA drives may have two connectors (SATA power connector or 4-pin Molex), choose between
the two but never use both because it could damage the drive
When you first remove a drive from the static-protective package, touch the package containing
the drive to a screw holding an expansion card or cover for at least two seconds to drain static
electricity from the package and your body
Fault tolerance is a computer’s ability to respond to a fault or catastrophe to prevent lost data
RAID (redundant array of inexpensive/independent disks) helps improve performance and fault
tolerance; requires a PCIe x16 slot
o There are four types of RAID – RAID 0, RAID 1, RAID 5, and RAID 10
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Spanning (JBOD) uses two hard drives to hold a single Windows volume; when the first disk is full,
it writes to the second
RAID 0 uses 2+ disks and writes to each disk evenly so neither disk performs all the activity;
Windows refers to it as a striped volume
o This is preferred to spanning
RAID 1 is a type of mirroring that duplicates data from one drive to another and is used for fault
tolerance, each drive has its own volume and these drives are hot swappable. If one drive fails,
the other continues to operate and data is not lost. Windows calls this a mirrored volume
RAID 5 stripes data and parity information across 3+ drives and uses parity checking so if one
drive fails, the others can re-create the data stored using parity information; this increases
performance and provides fault tolerance. These drives are hot swappable and referred to as
RAID 5
RAID 10 is mirrored data, where two disks are striped and requires 4 disks or more (even
numbers); it is the most expensive and provides the best redundancy and performance and allows
for hot swapping
RAID should be implemented before Windows is installed because all data on the assigned RAID
drives will be lost when you configure it
File system: overall structure the OS uses to name, store, and organize files on a drive
Formatting: a process that erases all data on a device or drive
File types:
o NTFS: hard drives
o exFAT: large capacity removable devices like USB flash drives, memory cards, and external
hard drives
o FAT32 / FAT: used by smaller capacity devices
o CDFS or UDF: used by CDs, a newer version of the UDF file system is used by DVDs and
Blue-ray discs
Know the difference between CD/DVD ROM (read only memory), R (recordable once), RW (rewritable), DL (dual layer to allow double storage), RAM (re-writable and erasable), RE
(rewritable), TL (triple layer), QL/XL QL (quad layer – used in data centers and cloud computing)
For the best performance, don’t allow an SSD to exceed 70% capacity and a magnetic drive to
exceed 80% capacity
The chkdsk C: /r command is immensely useful and allows you to repair the drive and recover
data
The bootrec /RebuildBCD allows you to ensure Windows can enter a successful boot
o bootrec /FixBoot command can be used to fix a corrupted boot sector
o bootrec /FixMBR command can be used to fix problems with the MBR program to start
Windows
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Max. Read Speed (if not listed in numbers)
Min. video write speed
Min. Write Speed
 Laptops have memory slots provided by a built-in smart
card reader
 Most popular type of memory cards are Secure Digital
(SD) cards
 The three standards for memory cards are 1.x (regular),
2.x (SD high capacity or SDHC), and 3.x (SD eXtended
Capacity or SDXC)
 4 Speeds can be 2, 4, 6, 10, UHS class 1, or UHSC class 3
o Class 4 or 6 is good for digital cameras
o HR video recording should use class 10
o The higher the speed, the more expensive the card
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Chapter 6 – Supporting I/O Devices
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An I/O or storage device can either be internal or external
Every device is controlled by software, and device drivers must be written for the OS
o Some simple devices are controlled by BIOS/UEFI
When it comes to installing or supporting a device, the manufacturer knows best
Some devices need application software to use the device
A device is no faster than the port or slot it is designed to use
Use an administrator account in windows when installing hardware devices
Problems with a device can sometimes be solved by updating the device drivers
Install only one device at a time
Device Manager is the primary windows tool for managing hardware and lists nearly all devices
and the drivers they use
When deciding the connection standard to use for a new device, the speed of transmission
standard is often the best comparison tool:
Port or Wireless Type
Thunderbolt 3
Thunderbolt 2
SuperSpeed+ USB (3.2)
SuperSpeed+ USB (USB 3.1)
eSATA Version 3 (eSATA-600)
SuperSpeed USB (USB 3.0)
eSATA Version 2 (eSATA-300)
eSATA Version 1 (eSATA-150)
Wifi 802.11ac – 5.0 GHz
Wifi 802.11n – 2.4 or 5.0 GHz
Lightning
Hi-Speed USB (USB 2.0)
Original USB (USB 1.1)
Wifi 802.11g – 2.4 GHz
Wifi 802.11a – 5.0 GHz
Wifi 802.11b – 2.4 GHz
Bluetooth – 2.45 GHz
NFC – 13.56 GHz
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Maximum Speed
40 Gbps
20 Gbps
20 Gbps
10 Gbps
6.0 Gbps
5.0 Gbps
3.0 Gbps
1.5 Gbps/1500 Mbps
1.3 Gbps/1300 Mbps
Up to 600 Mbps
480 Mbps
480 Mbps
12 Mbps / 1.2 Mbps
Up to 54 Mbps
Up to 54 Mbps
Up to 11 Mbps
Up to 3 Mbps
Up to 424 Mbps
Wireless Range
Copper up to 2m, requires USB-C
Copper up to 100m
1m, requires USB-C
Up to 3m
Up to 2m
Up to 3m
Up to 2m
Up to 2m
Up to 70m
Up to 70m
Up to 2m
Up to 5m
Up to 3m
Up to 100m
Up to 50m
Up to 100m
Up to 10m
Up to 4cm
USB Implementors Forum, Inc is the organization responsible for developing USB
o As many as 127 USB devices can be daisy chained together
o USB uses serial transmission and are hot swappable
o USB cables have four wires – two for power, two for communication
o Three general USB port categories are Mini USB, micro USB, and regular USB
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USB Cables and connectors:
Cable Type
A Cable
Description
Flat, wide, and connects to a USB port
Micro-A
Has five pins, smaller than the Mini-B and is used on cells phones and other small devices
B Cable
Square, connects to a USB 1.x or 2.0 device such as a printer
Mini-B
Has 5 pins and is often used to connect small electronic devices to a computer
Micro-B
Has 5 pins and has a smaller height than the Mini-B connector. Used on tablets, cell
phones, and other small electronic devices
C Cable
Flat with rounded sides, do not have a specific orientation and are backward compatible
with USB 2.0/3.0. This is required to reach maximum speeds with USB 3.2
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Most mobo’s sold today have one or more video ports integrated called onboard ports; make sure
you can disable the video port if it gives you trouble
Video card can use a PCI or PCIe slot, with PCIe x16 being the fastest
Types of Video Ports:
Cable Type
VGA
Description
15-pin analog video port and transmits 3 signals of red, green, and blue.
DVI-D
Transmits only digital data
DVI-I
Supports both digital and analog
Display
Port/Mini
Designed to replace DVI and can transmit digital video and audio, uses data packet
transmission. Expected to replace VGA, DVI, and HDMI
HDMI/Mini
Transmits both digital video and audio, designed for home theatres
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RG-6 coax used for cable TV, having replaced the RG-59
o Often uses a BNC connector
RS-232 have been replaced by USB, once were used with mice, keyboards, dial-up and other
peripherals
o All RS-232 connectors today use 9 pins and are often called a DB-9 connector
A graphics tablet is often called a digitizing tablet or digitizer
A KVM (keyboard, video, mouse) switch allows you to use one keyboard, monitor, and mouse
for multiple computers and does not require that you install device drivers to use it
Laptops contain Mini PCI Express slots that use 52 pins on the edge connector
o Often used to enhance communication options for a laptop, including wifi, cellular WAN,
video, and Bluetooth.
The primary output device of a computer is a monitor
o Two necessary components for video output are the monitor and the video card
o LCD (liquid crystal display) – flat panel monitor, uses liquid crystal to produce an image
and uses pixels to form an image
o OLED (organic light-emitting diode) – uses thin LED and does not use backlighting,
produces deeper blacks and better contrast, but have more glare. Often used by mobile
devices.
o Laptop displays almost always use LCD technology
Monitor characteristics:
Monitor
Description
Characteristic
Screen Size
Diagonal length of the screen in inches
Refresh Rate Number of times a monitor screen is refreshed in 1 second, measured in Hz. The higher,
the better. Response time is the time it takes to build 1 frame, measured in ms. The
lower, the better
Pixel pitch
Dot on the screen that can be addressed by software – pixel pitch is the distance
between adjacent pixels on the screen. The smaller, the better
Resolution
Number of spots or pixels on a screen
Contrast
Contrast between true black and true white – the higher, the better
ratio
Viewing
Angle at which a monitor becomes difficult to see from the side
angle
Backlighting
Measured in cd/m2, the best LED backlighting is class IPS as it provides the most
or brightness accurate colour
Connectors
VGA, DVI-I, DVI-D, HDMI, DisplayPort, Thunderbolt
Other
features
LCD can provide privacy or antiglare; some are also touchscreens
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Things that can go wrong when installing a video card and what to do:
o Hear whining sound - caused by lack of power, check PSU and wires
o Black screen – onboard video not being disabled in BIOS/UEFI
o Series of beeps – cannot detect video card
o Error messages about video appear when Windows starts – conflict between onboard
video and video card
o Games crash/lock up – update drivers for mobo, video card, and sound card. Install the
latest version of DirectX
Burn-in is when a static image stays on a monitor for many hours, leaving a permanent
impression of that image
o Can try to prevent this by using a moving screen saver or rotating various images
Distorted geometry is where images are stretched
ClearType helps improve the quality of text on a screen
Dead pixels are often caused by dead transistors, which cannot be fixed
If you see artifacts on the screen before Windows loads, the problem is not caused by the
drivers and potentially by the monitor
o Overclocking can cause artifacts
Chapter 7 – Setting Up a Local Network
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A network is created when two or more computers can communicate with each other
Categories of networks based on size, from smallest to largest:
o PAN – Personal area network, generally 802.11 or Bluetooth
o LAN – Local area network, covers a small local area such as a home, office, or small
group of buildings
o WMN – Wireless mesh network, commonly used for IoT
o MAN – Metropolitan area network, covers multiple buildings in a large campus or
portion of a city
o WAN – wide area network, covers large geographical areas and is made up of many
smaller networks. Best known WAN is the Internet
Bandwidth – theoretical number of bits that can be transmitted over a network connection at a
time
Throughput – average of the actual speed
Latency – measured by the round-trip time it takes for a message to travel from source to
destination and then back
Wireless wide area network (WWAN), also called a cellular network, is provided by companies
o Two established cellular connections are GSM (global system for mobile
communications) and CDMA (code division multiple access)
o LTE (long term evolution) will replace GSM and CDMA
o Devices that use GSM or LTE require a SIM (subscriber identification module) card
You can tether computers or other devices to cellphones to provide communication to the
tethered device
Universal Plug and Play (UPnP) helps computers on the local network automatically discover
and communicate with services provided by other computers on the local network
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Technology
Maximum Speed
Description
Wireless Connections: Satellite and WiMAX
Satellite
Up to 15 Mbps
Requires a dish in a relative fixed position
WiMAX
Up to 30 Mbps
Requires transmitter to send and receive from a tower
up to 30miles away. Being replaced by LTE
Wireless Internet connection: Cellular
3G cellular
At least 200 Kbps,
Allows for transmitting data and video. Uses either
can be up to 4 Mbps CDMA or GSM phone services
4G cellular
100 Mbps to 1 Gbps Higher speeds achieved when in a fixed position,
generally uses LTE (long term evolution)
5G cellular
10-50 Gbps and
beyond
Wired Internet connections: Telephone
Dial up or POTS
Up to 56 Kbps
Slow access to ISP using modem and dial-up over
phone lines
ISDN
64/128 Kbps
ISDN (integrated services digital network) is outdated
business-use connections to ISP over dial-up
SDSL (Symmetric Up to 22 Mbps
Equal bandwidth in both directions, type of
Digital
broadband (carries more than one type of signal);
Subscriber Line)
uses regular phone lines
ADSL
640 Kbps up and up
Most bandwidth allocated for data coming from ISP
to 24 Mbps down
VDSL (very-high- Up to 70 Mbps
Type of asymmetric DSL that works only over short
bit-rate-DSL)
distances
Other wired connections
Cable internet
Up to 160 Mbps
Connects home or SOHO to ISP
Dedicated line
Up to 43 Tbps
Dedicate fibre line from ISP
using fibre
Wired local network: Ethernet
Fast Ethernet
100 Mbps
Used for local networks
(100BaseT)
Gigabit Ethernet 1 Gbps
Fastest Ethernet standard for small, local networks
(1000BaseT)
10-Gigabit
10 Gbps
Typically requires fibre media, mostly used on the
Ethernet
backbone of larger enterprise networks, can only be
(10GBaseT)
used on WAN connections
Wireless local network: Wifi
802.11a
Up to 54 Mbps
Not used
802.11b
Up to 11 Mbps
Experiences interference from cordless phones and
microwaves
802.11g 2.4 GHz Up to 54 Mbps
Compatible with and has replaced 802.11b
802.11n 2.4/5.0 Up to 600 Mbps
Uses MIMO (can have up to 4 antennas)
802.11ac 5.0
Up to 8 Gbps, but at Supports up to 8 antennas and supports
GHz
1.3
beamforming (detects connected devices and
increases signal strength in that direction)
802.11ad
Up to 7 Gbps
Only achieved when within 3.3m of AP
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Port address – applications defined by the port they are sent out of
o Most applications used on the internet or local network are client/server
applications
o Port forwarding – opening certain ports to certain computers so that activity
initiated from the internet can get past the firewall
DMZ (Demilitarized zone) – a network not protected by a firewall or has limited protection
Ranges and frequencies for wireless standards:
o 802.11a – 50m, 5.0 GHz
o 802.11b – 100m, 2.4 GHz
o 802.11g – 100m, faster than 11b at 54 Mbps
o 802.11n – Indoor range of 70m, outdoor of 250m, can be 2.4 GHz or 5.0 GHz
o 802.11ac – Indoor range of 70m, outdoor of 250m, only 5.0 GHz and has stronger
performance at the edge of its reach compared to 802.11n
Three main security standards for 802.11 wireless are:
o WEP (wired equivalent privacy) – no longer consider secure, key is static
o WPA (wifi protected access) – stronger than WEP and designed to replace it,
typically uses TKIP (temporal key integrity protocol), no longer considered secure
o WPA2 (wifi protected access 2) – also called 802.11i standard, current standard.
Typically uses AES (advanced encryption standard), which is faster and more secure
encryption than TKIP
o WPA3 (wifi protected access 3) – better encryption, can securely configure a nearby
wireless device, eliminating the need for a wired connection to configure it. Includes
IDE (individual data encryption)
SSID (service set identifier) – name of a wireless network
Channel – specific radio frequency within a broader frequency. To avoid overlap, the 2.4
GHz pick channels 1, 6, or 11. The 5 GHz band offers up to 24 channels.
Some high-end access points allow radio power level adjustment to reduce interference,
save on electricity, or limit the range of the network to your own property
Wifi protected setup (WPS) – generates the SSID and security key using a random string of
hard-to-guess letters
o can be a security risk if not managed well
ping command:
o ping <network> - tests connectivity using an IP address
o ping -a <network> - tests for name resolution to verify DNS is working
o ping -t <network> - continues pings until interrupted
o ping 127.0.0.1 – the IP address 127.0.0.1 always refers to the local
computer. This is a loopback address. If the local computer does not respond, there
is a problem with network config
o ping cengage.com – uses a host name to find out the IP address of a remote
computer
ipconfig command:
o ipconfig /all – displays a network connection’s configuration information
o ipconfig /release – releases IP address and other TCP/IP assignments
o ipconfig /release6 – releases IPv6 and other TCP/IP assignments
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ipconfig /renew – leases a new IP address from DHCP
ipconfig /renew6 – leases a new IPv6 address from DHCP
ipconfig /displaydns – displays info about name resolution
ipconfig /flushdns – flushes the name resolution cache, might solve
problems with browser cannot find a host on the internet
nslookup (namespace lookup or name server lookup) – used to test name resolution
with DNS servers allowing you to request information from a DNS server’s zone data, which
is the portion of the DNS namespace that the server knows about
tracert - useful when trying to resolve a problem reaching a destination host such as
an FTP site or website
netuse – requires elevated command prompt access, connects or disconnects a
computer from a shared resource or can display information about connections
netuser – manages user accounts
netstat – gives statistics about network activity and includes several parameters:
o netstat – list stats about network connection, including IP addresses of active
connections
o netsat >> netlog.txt – direct output to a text file
o netsat -b – lists programs using the connection, useful for finding malware
o netsat -b -o – includes process ID of each program listed to use taskkill
command
o netsat – a – lists stats about all active connections and the ports the
computer is listening on
Chapter 8 – Network Infrastructure and Troubleshooting
*NOTE: Several notes have been left out of this chapter due to coverage in the Network+ and CCNA
course.
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Types of IPv6 Addresses:
o Link: local area network
o Node: any device that connects to the network
o Neighbors: nodes on the same LAN
o Multicast address: delivers messages to all nodes in a targeted multicast group
o Anycast address: delivered only to the closest destination
o Unicast address: send messages to a single node. Three types of unicast addresses are:
 Link local: used for limited communication with neighboring nodes on the same
link. Begin with FE80::/64 and end in %
 Unique local: private addressed assigned by a DHCP6 server that can
communicate across subnets within a private network. Always begins with FC or
FD
 Global address: can be routed on the internet, the first 48 bits of the address is
the Global Routing Prefix
IPv6 uses subnetting but doesn’t need a subnet because the subnet ID is a part of the address
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FQDN is a fully qualified domain name and must be associated with an IP address
TCP/IP protocols used by applications:
o HTTP: used for the internet by web browsers and servers to communicate
o HTTPS: refers to HTTP using a secure socket layer (SSL) or Transport Layer Security (TLS)
to create a secure socket, TLS is better than SSL. A socket is a connection between a
browser and a web server
o SMTP – simple mail transfer protocol is used to send mail
o POP and IMAP – used to receive mail. POP3 downloads email to the client from an
email server. IMAP4, the client manages the email while it is still stored on the server
o RDP – remote desktop
o SSH – secure shell encrypts communicate to prevent hacking
o FTP – file transfer protocol, used to transfer a file between two computers over a WAN
or LAN. FTP is not secure. FTPS uses SSL encryption, and SFTP uses SSH encryption
o SMB – server mail block is a file access protocol to share files and printers on a network.
SMB3 and CIFS are the latest versions
o AFP – apple filing protocol is a file access protocol
o LDAP – lightweight directory access protocol used when applications need to query a
data base for things such as the email addresses for all employees, is not encrypted.
o SNMP – simple network management protocol is a protocol used to monitor network
traffic and manage network devices
Ethernet over Power uses power lines in a building to transmit data, but this data is sent out on
a network that you cannot necessarily contain because power lines are not confined to a single
building
o Powerline adapters offer 128-bit AES encryption activated by pairing the adapters
Power over Ethernet allows power to be transmitted over Ethernet cable, and can provide up to
25.5 watts from a single port
o If a switch does not offer PoE, you can attach a PoE injector which adds power to an
ethernet cable
Chapter 9 – Supporting Mobile Devices
*NOTE: Several notes have been left out due to the familiarity with mobile devices.
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IMEI – internal mobile equipment identity is a unique number that identifies each mobile phone
or tablet device worldwide
IMSI – international mobile subscriber identity is a unique number that identifies a cellular
subscription for a device or subscriber along with its home country and mobile network
PRL is a preferred roaming list database file that lists the service providers or radio frequencies
your carrier wants the device to use when outside your home network
S/MIME (secure/multipurpose internet mail extensions) is a more secure protocol than SMTP,
which encrypts the email and includes a digital signature to validate the identity of the sender
End of life limitations – a device that ages out of the vendor’s updates
Product release instructions – describe new features or patches the update provides and how
long the update will take
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Back up and recovery:
o File level backup – syncing information through online accounts or to your computer
o Partial image – backs up settings, native app data, Wifi password, account profile, and
device/app configuration
o Combination of file-level and partial image – prepares for catastrophic failure or loss by
using both file level and partial image
o Image level – includes everything on the device and can completely restore the device
to its previous state. Some OS don’t support this
Internet of Things:
o Z-wave – transmits around 900 MHz band and requires less power than wifi, reaches up
to 100m
o Zigbee – 2.4 GHz or 900 MHz band, requires less power than wifi, generally reaches an
inside range of 20m
 Both can connect in a mesh network
 Zigbee is generally for large-scale commercial/industrial
o RFID – radio frequency identification is traditionally used in small tags that attach to and
identify clothing inventory, car keys, bags, luggage, etc. Contains a microchip and
antenna
Chapter 10 – Virtualization, Cloud Computing, and Printers
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Virtualization is when one physical machine hosts multiple activities that are normally done on
multiple machines. There are two types:
o Application – one computer can serve up to multiple apps
o Desktop – also called client-side virtualization. This is when one computer provides
multiple desktops for users, each virtual desktop is contained in its own virtual machine
 Software called a hypervisor creates and manages virtual machines (VMs) that
have their own virtual hardware
Hypervisor software can be type 1 or type 2, the main difference being whether the host
computer has its own OS:
o Type 1: installs on a computer before any OS and is called a bare-metal hypervisor
 Ex: XenServer, KVM, ESXi
 For server-hosted desktops, most likely the hypervisor used is a type 1
o Type 2: installs a host OS as an application and is sometimes called a hosted hypervisor
 Ex: Hyper-V, Oracle VirtualBox, VMware Workstation
 Not as powerful as type 1 because it is dependent on the host OS to allot its
computing power
Developers us VMs to test applications, help-desk techs use it to switch from one OS to another
when a user asks for help
Honeypots are used to lure hackers to protect the real network
Hardware-assisted virtualization (HAV) must be enabled on the processor settings to enhance
processor support for virtual machines
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Cloud computing is when a vendor or corporation makes computing resources available over
the internet, such as cloud file storage and synchronization apps on mobile devices and
computers to sync data
o Public cloud – provided over the internet to the general public
o Private cloud – services established on an organization’s own servers for private use
o Community cloud – services are shared between multiple organizations with a common
interest, but not available publicly
o Hybrid cloud – combination of public, private, and community clouds used by the same
organization
All cloud computing service models incorporate the following elements:
o On-demand services
o Rapid elasticity to scale up or down
o Support for multiple client platforms – refers to the OS
o Resource pooling and consolidation – services to multiple customers are hosted on
shared physical resources
o Measured service – measured or metered for billing purposes
Cloud computing service models:
o
o
IaaS (infrastructure as a service) – customer rents hardware, including servers, storage,
and networking, and can use these hardware services virtually
 Ideal for fast-changing applications, to test software, or for start up businesses
PaaS (platform as a service) – customer rents hardware, OS, and some applications
 Popular with software devs
 Ex: Google Cloud Platform and Microsoft Azure
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SaaS (software as a service) – customers use applications hosted on the service
provider’s hardware and operating systems, and typically access the applications
through a web browser
 Ex: Gmail, Yahoo mail
o XaaS (Anything as a service or Everything as a service) – cloud can provide any
combination of functions depending on a customer’s exact needs
Thick client – fat client; regular desktop computer or laptop that is sometimes used as a client
by a hypervisor server
Thin client – has an OS but little computing power of its own and might only need to support a
browser
o Reduce cost by meeting only minimum requirements for a basic OS, support basic apps
required for interaction with server, and support high-speed network connectivity
Zero client – dumb terminal; does not have an OS and is little more than an interface to the
network with a keyboard, monitor, and mouse
o Ex: Wyse Zero
Persistent VDI – user owns the virtual desktop and can customize it
Nonpersistent VDI – user receives a desktop from a pool and each time the user signs on, the
desktop reverts to its original state
7 steps of laser printing:
1. Processing – firmware inside the printer processes the incoming data to
produce a bitmap
2. Charging/Conditioning – drum condition by roller that places an electrical
charge of -600 to -1000 V on the surface; roller is called the primary charging
roller or primary corona
3. Exposing/Writing – laser beam controlled by motors and a mirror scans across
the drum until it completes the correct number of passes
4. Developing – developing cylinder applies toner to surface of drum, toner is
charged between -200 to -500 V to stick to the developing cylinder; a control
blade prevents too much toner from sticking to the drum
5. Transferring – strong electrical charge draws the toner off the drum onto the
paper; the transfer roller puts a positive charge on the paper to accomplish this
6. Fusing – the fuser assembly uses heat and pressure to fuse the toner to the
paper
7. Cleaning – sweeping blade cleans the drum of any residual toner
The charging, exposing, developing, and cleaning steps use the most printer components that
undergo the most wear
Transfer belt – does the transferring and can be replaced in some printers
Pickup roller – pushes a sheet of paper forward
Separation pad – ensures that only one page of paper is moving forward into the printer
Inkjet printers use ink-dispersion using a print head
o Highly dependent on paper quality
Impact printer – creates a printer image using a mechanism that touches or hits the paper, such
as a dot matrix printer
Thermal printer – use heat to create an image
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o Can be direct that burns dots onto specially coated paper called thermal paper
o Can be transfer that uses a ribbon that contains wax-based ink
o Suggested to clean the head with isopropyl wipes
Local printer – connects directly to a computer by a physical port
Network printer – has an ethernet port connected directly to the network or uses wifi to
connect to a wireless access point
Wifi adhoc mode is when a wifi printer can connect directly to a nearby computer using a wifi
hotspot, a computer hotspot, or a device-to-device connection called an ad hoc network
Integrated print server – printers that connect directly to a router or switch so devices can find
the printer
Computer as a print server – a computer shares its local printer with other computers on the
network
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