Welcome to the first half, CompTIA A+ 220-901 study notes. This is quite the wall of text so a fair warning if you have a weak PC.

Luckily, it's only text.

As much as I wanted to throw in images and videos, it just made this article load too slow. It was even slow with my beefy computer, beefy internet connection, and optimized VPS hosting for this website.

Update 8/26/18: that could be because of the theme I was using previously. Things seem to be smoother now.

This information came from some knowledge I already had being in the industry and taking the exam many years ago. Other parts came from random articles including Wikipedia and a few YouTube videos. I'd say a good portion of this is my own words but I did have to lookup a few things, especially things that are technically correct but is no longer usable (best practices and older architecture stuff). I ordered this guide by the 220-901 exam objectives and filled in the blanks.

Know going into this that you won't retain all industry knowledge at all times. I'll happily admit I don't have this entire page of notes memorized. What's more important is taking notes and knowing where to look when you need to recall something or fix an issue.

Treat these notes as a review. You should be shaking your head yes as you go through these notes. Learn and retain as much of the concepts as possible. There's no shortcut to being an IT pro. Put the work and and do great.

Let me know how you do. The CompTIA A+ 220-902 study notes are up next. Good luck!

Table of Contents

Section 1: Hardware

1.1 – BIOS and UEFI

Types of BIOS

UEFI – Unified Extensible Firmware Interface
  • GUI with mouse support
  • Implemented by manufacturers
  • Think of it as updated BIOS tech
  • Support for boot from large GPT disks (<2.2TB)
  • Pre–boot has it’s own OS
    • PXE – Preboot Execution Environment
    • Enables booting from a network device
    • Apple devices have Apple Netboot
  • Able to connect remotely
  • Modular by design with a wide compatibility
BIOS – Basic Input / Output System
  • The software or motherboard firmware you see when you start your computer
  • BIOS chip is on the motherboard
  • CPU performance, memory performance, and more can be configured here
  • You can also set a password at the BIOS level to keep anyone from making changes
  • Initial hardware checks (POST)
    • POST – Power on self test
    • Basic hardware diagnostic tests
    • Indicates status through beeps
  • Allows OS to interact with hardware
    • This is the same purpose as device drivers
  • After BIOS, computer looks for boot devices in a set order
  • Settings are saved in nonvolatile memory (ROM chip)
    • EPROM/EEPROM – (Electrically) Erasable programmable read–only memory
    • Retains data even when powered off.
    • Used to store mission–critical data that doesn't require initialization (BIOS)
    • This sounds familiar because flash memory also serves this purpose
  • MSinfo32.exe allows user to view basic information about BIOS
    • You can also make changes through this executable as well
  • CMOS Ram – ram supported by small batteries in order to retain settings after power off
  • Supervisor password is the highest permission level
  • Secure boot capability will only run applications with known–good signatures
Legacy BIOS
  • Limited hardware support
  • Over 25 years old

BIOS Configuration

  • RAM – view and configure memory settings
  • Hard drive/ SSD – view and enable/disable
  • Optical drive – view and enable/disable
  • CPU – Adjust settings
  • Hardware diagnostics – Built in BIOS
  • Firmware – It's usually best practice to not upgrade unless there are fixes you need or current build is having issues

BIOS Security

  • BIOS password / User password – system OS will not start without the BIOS password
  • Supervisor password – think of this password as an admin account password that is required to make BIOS changes
  • Full disk encryption – encrypts everything on disk
  • TPM – Trusted Platform Module
    • Built in chip to motherboard. Can be added
    • Used by the full disk encryption process for password protection and other security features
    • Retains encryption keys, signatures, and other security information
    • Enables DRM for certain media
    • Integrates with Windows BitLocker
  • LoJack for Laptops (formally known as CompuTrace)
    • Built into the BIOS
    • Automatically installs to storage
    • Useful for tracking lost or stolen devices
    • Phone home function sends location info to central location
    • Theft Mode allows you to delete files or simply lock down the device
  • Secure Boot – compares digital signatures to the OS you're running

Installing BIOS Upgrades

  • Upgrading firmware
    • Upgrade done to nonvolatile memory so you'll need a reliable power source for no interruptions
    • Improves performance or fixes bugs
    • It's usually best practice to upgrade if you're having problems so you don't introduce new problems to an already functioning system
    • Modern upgrades run from .exe files
  • You can identify the BIOS version
    • At BIOS startup screen
    • In Windows devices – MSinfo32.exe

1.2 – Motherboards

There are many different types of motherboards (over 40 different types) but there are 3 main form factors.

Form Factors

ATX – Advanced Technology Extended
  • Regular size motherboards
  • Uses 20 or 24 pin power connector
  • May see an addition 4 or 8 pin connector
  • Includes I/O backplate
Micro ATX
  • Smaller ATX motherboards
  • Backwards compatible as long as the components can fit the smaller form factor
  • Similar power connectors to ATX
  • Will mount in an ATX case
ITX
  • Series of smaller motherboards
  • Heat (airflow) can be an issue
  • Mini, Nano, Pico, Mobile form factors
  • Developed by VIA tech in 2001
  • Screws compatible with ATX and Micro ATX
  • Ideal for single use computing like media streaming

Expansion Slots and Bus Speeds

Bus width
  • How much traffic can pass (throughput)
  • Each part of motherboard is connected via bus
  • Each bus has a clock speed, which is how fast the bus can go
Clock Speed
  • Measured in Hertz
  • 1 MHz = megahertz = 1 million cycles/second
  • 1 GHz = 1000 MHz
  • Clock speed can be multiplied
PCI – Peripheral Component Interconnect
  • Communicates data in parallel between the south bridge and the PCI device
    • 32 and 64 bit bus length
    • 32 bit = 32 lines of communication
    • 64 bit = 64 lines of communication
  • 32 bit slots are shorter
  • Parallel bus means that all bits are transferred at once
PCIx – PCI Extended
  • More throughput
  • Higher speed
  • Parallel communication
  • Designed for servers
PCIe – PCI Express
  • Replaced PCI, PCIx, and AGP
  • Communicates serially, faster than parallel
  • x1, x2, x4, x8, x16, and x32 full duplex transfer lanes
  • Slots have varying physical lengths
  • v1.x – 250 MB/s
  • v2.x – 500 MB/s
  • v3 – 1 GB/s
  • v4 – 2 GB/s
Mini PCI and PCIe Mini
  • Similar design but smaller
  • Can have WiFi cards
  • Made for laptops

RAM Slots

DIMM – Dual Inline Memory Module
  • Standard memory chip
  • One single chip set
  • Electrical contacts are different on each side
  • 64 bit data width
  • Double Data Rate (DDR) SDRAM – 184 pins
  • DDR3 and DDR3 SDRAM – 240 pins
  • You can tell what DDR it is by where the tab in the middle of the connections is
SO–DIMM – Small Outline Dual Inline Memory Module
  • Smaller form used in laptops
  • DDR and DDR2 – 200 pins
  • DDR3 – 204 pins
Micro DIMM
  • Very small, used in small laptops and other mobile devices
  • DDR – 172 pins
  • DDR2 and DDR3 – 214 pins

CPU Sockets

Based on motherboard and CPU combination.

ZIF – Zero Insertion Force
  • Many tiny pins on the CPU
  • Holes are in motherboard connector
LGA Socket – Land Grid Array
  • Tiny pins on motherboard instead of CPU
Common Types
  • Intel
    • LGA 775
      • 775 pins
      • Also called Socket T
      • Pentium 4, Intel Core 2 Duo, Xeon, and Celeron
      • Released in 2004
    • LGA 1366
      • 1366 pins
      • Socket B
      • Replaced 775
      • Intel Core I7
      • Released in 2008
    • LGA 1156
      • 1156 pins
      • Socket H1
      • Also replaced 775
      • Integrates Northbridge into the chip
      • I3 / I5 /I7
      • Released in 2009
    • LGA 1155
      • Socket H2
      • Supports Sandy Bridge and Ivy Bridge CPU
      • Released in 2011
    • LGA 1150
      • Socket H3
      • Haswell and Broadwell architecture
      • Released in 2013
    • LGA 2011
      • Socket R
      • Replaces 1366 and 1567
      • Sandy Bridge–E/EP and Ivy Bridge–E/EP (enthusiast/xeon class)
      • Released in 2014
  • AMD
    • AM3
      • 941 pins
      • Replaces Am2/Am2+
      • PGA
      • Released in 2009
    • AM3+
      • 942 pins
      • PGA
      • Released in 2011
    • FM1
      • 905 pins
      • AMD 10H architecture
      • A–series process
      • DDR3 support, integrated PCI–e
      • Released in 2011
    • FM2
      • 904 pins
      • Piledriver architecture
      • Released in 2012
    • FM2+
      • 906 pins
      • Micro PGA – ZIF package
      • Steamroller architecture
      • Released in 2014

Chipsets

Chipsets vary in bus speeds, cooling systems, layouts, and more.

Northbridge
  • Central memory connector
  • Connects the CPU to the memory and high speed graphics Card (PCIe or AGP)
  • High bandwidth
Southbridge
  • Central manager
  • Connects the PCI interface slots, USB, Ethernet, IDE, BIOS, onboard graphics, etc.
Super I/O
  • Single chip that handles I/O for serial and parallel ports, floppy disk, keyboard, mouse, and other low bandwidth devices
Modern Boards for CPUs
  • Chipsets using Ivy bridge, which combines many functions
  • Most have multiple cores, memory controllers, and GPUs integrated
  • Reduces reliance on a slower bus
  • Allows for more devices to be consolidated and handled by functions with higher speed

Motherboard Jumpers and Connectors

  • Connects reset button, power button, NIC connectors, speaker (optional), fans, LEDs, and more
  • Enable or disable certain features, often labeled JP
  • A connector covers 2 or more pins you want to jump
  • Could be used to reset BIOS

1.3 – Ram

  • RAM – Random Access Memory
  • ROM – Read Only Memory
    • Does not change (BIOS)
    • PROM – Programmable Read Only Memory
      • Written once
    • EPROM – Erasable PROM
      • Write / erase / write again
    • EEPROM – Electrically Erasable PROM
      • Flash memory, SSD
  • SRAM – Static RAM
    • Very fast, large, and expensive
    • Used often in CPU caches (L1, L2, L3)
  • DRAM – Dynamic RAM
    • Needs constant refreshing or memory disappears
    • Data can be stored anywhere and accessed directly
  • SDR SDRAM – Single Data Rate Synchronous DRAM
    • Synchronized with clock cycles
    • Very slow
    • Queues a process while waiting on another
    • 168 pins
  • DDR – Double Data Rate
    • Twice as fast as SDR
    • Typical memory
    • Multiplies data rate by the clock speed
    • 184 pins
    • Example
      • DDR–200 = 200 Million transfers per second = Clock speed = 100 MHz
      • DDR means two transfers per clock
      • 200 million transfers
      • Multiply by 8 to get throughput in MB/s
  • DDR2 – Twice as fast as DDR
    • 240 pins
    • Example
      • DDR2–400 = Clock speed = 100 MHz
      • DDR2 means four transfers per clock
      • 400 million transfers
      • Multiply by 8 to get throughput in MB/s
  • DDR3 – Twice as fast as DDR2
    • 240 pins
    • Example
      • DDR3–800 = Clock speed = 100 MHz
      • DDR3 means eight transfers per clock
      • 800 million transfers
      • Multiply by 8 to get throughput in MB/s

All 3 DDRs are not backwards compatible with each other since the notches are off.

Understanding PC Memory

Parity Memory
  • Adds additional parity bit to detect simple errors
  • Will not always detect error
  • Will not fix error
ECC Memory
  • Error Correcting Code memory
  • Detects and fixes errors
  • Not used by all systems
    • Expensive, used by enterprise systems
  • Even parity, parity bit makes an even number
Registered Memory
  • Used in servers
  • Buffer zone
  • To stabilize the OS
  • You can see chips in the middle of the stick
Multi–channel Memory
  • Installed in pairs or trios for max throughput
  • Combinations need to match
Buffered Memory
  • Used to place less electrical load on the memory controller
Single–Sided vs Double–Sided
  • Can be physical
  • “Ranks” of memory
  • Think of virtual separation between RAM

1.4 – PC Expansion Cards

  • Huge amount of PC expansion card types
  • You'll have additional options for expansion of upgraded video, audio, storage, and even network capabilities
  • Most motherboards include several expansion card slots
  • Check requirements, documentation, and other user experiences for a card your interested in getting

1.5 – Storage Devices

  • Optical storage
    • Small bumps are written to disc with a laser
    • CR–ROM
      • 700 MB capacity
      • R
      • RW
    • DVD–ROM
      • Single layer – 4.7 GB
      • DL – 8.5 GB
      • R
      • RW
    • Blu–ray
      • Single layer – 25GB
      • Dual layer – 50GB
      • R
  • HDD – Hard Disk Drive
    • Mechanical, spinning drive
    • Slower speeds
    • Can break as it has moving parts
  • SSD – Solid State Drive
    • No moving parts
    • Very fast, usable for boot drives
    • Flash memory
  • SSHD – Solid State Hybrid Drive
    • Has spinning drive and SSD flash memory
    • Faster than a regular HDD
    • More hard disk than solid state
    • Uses flash memory to cache in order to increase I/O rate
  • Hot swappable
    • Remove or add without powering off machine
    • USB, firewire, SATA, eSATA
  • SD – Secure Digital
    • Memory card mostly used in cameras and other smaller devices for storage
  • USB Flash Drives
    • EEPROM – Electrically Erasable Programmable ROM
    • Nonvolatile – loss of power does not erase data
    • Limited number of writes
    • Easy to damage casing and memory chip
  • Tape drives
    • Magnetic tape
    • Cheap, long term storage
    • Sequential storage
    • LTO – Linear Tape Open
      • Ultrium form factor

RAID

RAID 0
  • Striping – data files split between 2 or more drives
  • High performance
  • No redundancy, one bad drive = data loss
RAID 1
  • Mirroring – exact duplicate of data across 2 or more drives
  • Redundancy
  • Not speed
RAID 5
  • Striping with parity – files are striped
  • Requires at least 3 drives
  • High redundancy
  • Efficient use of disk space
  • Parity calculation may affect performance
RAID 1+0
  • Stripe of mirrors
  • Requires at least 4 drives
  • Speed of striping and has redundancy of mirroring

1.6 – CPU Technologies

CPU Characteristics

  • CPU Clock
    • Primarily in GHz
  • Actual Speed
    • Comprised of clock speed, architecture, bus speed, bus width, L1/L2 cache size, OS
    • Are no longer marketed on clock cycles, instead on key features
    • No clear benchmark for performance
  • Multi–core
    • Each core in a multi–core could have its own L1/L2 cache, but could share an L3 cache
  • Caches
    • Very fast memory
    • Increased throughput significantly
    • L1 – First check
    • L2 – Secondary Data
    • L3 – Tertiary Data
  • HTT – HyperThreading Technology
    • Pretends to be multiple cores
    • 15–30% improvement over raw cores
  • Intel Virtualization Technology VT (AMD–V)
    • Enables virtualization within processor
    • Greatly improves virtual OS
  • 32 bit vs 64 bit
    • 64 bit has more data ‘width’
    • Bigger integer size, larger memory addresses, larger bus size
    • Can move twice as much data as 32 bit
    • OS must be optimized for 64 bit
  • Integrated GPU
    • Helpful, power users rarely use
  • Integrated Security – NX bit – No eXecute bit
    • Intel calls it XD bit eXecute Disable
    • Memory areas where code can’t run
    • Windows calls it DEP – Data Execution Prevention
  • CPU Cooling
    • Heat sink of copper or aluminum
    • Sits on chip with a thin layer of thermal paste
    • Water cooling can be a custom loop or all in one cooler
    • Some smaller devices just use heatsinks, no fans

1.7 – Interfaces

USB 1.1
  • 1.5 Mb/s – 12 Mb/s
  • 3 – 5 meters max
USB 2.0
  • 480 Mb/s
  • 5 meters max
  • A, B, Micro, Mini plugs
USB 3.0
  • Also called Superspeed
  • 5 Gb/s
  • 3 meters max
  • A, B, Micro plugs
Firewire
  • Apple trademark, IEEE 1394
  • Daisy chain up to 63 devices
  • 4.5 meters (15 ft) distance limit per link
  • Firewire 400
    • 100, 200, and 400 Mb/s
    • Half duplex
    • Alpha mode 1394a
  • Firewire 800
    • 800 Mb/s full duplex
    • Optical support up to 100m range
    • Beta mode 1394b
Sata
  • Pins
    • Power – 15 pins
    • Data – 7 pins
  • 1.0 – 1.5 Gb/s
    • 1 meter range
  • 2.0 – 3 Gb/s
    • 1 meter range
  • 3.0 – 6 Gb/s
    • 1 meter range
eSata
  • Matches regular sata revisions
  • 2 meter range
VGA – Video Graphics Array
  • Blue DB–15 connector
  • 5–10 meters max range
  • Analog signal only
HDMI – High Definition Multimedia Interface
  • All digital signal
  • 20 meter range before signal loss
  • 19 pin type A connector
    • Proprietary
  • Type C connector for MiniHDMI (like cameras)
  • 4–14 Gbps depending on type
    • 1.0 = 4 Gbps
    • 2.0 = 14 Gbps
BNC – Bayonet Neill–Concelman
  • High end video
Mini–DIN
  • S video
  • 2 channel analog
DVI – Digital Video Interface
  • DVI–A: Analog
  • DVI–D: Digital
  • DVI–I: Integrated (digital and analog)
  • Single link – 3.7 Gbps HDTV at 60 fps
  • Dual link – 7.4 Gbps HDTV at 85 fps
Digital Toslink
  • Old consumer grade fiber
  • 10 meter range
Audio Ports
  • Analog TRS plugs (Tip, Ring, Sleeve)
  • ¼” = 6.5mm
  • ⅛” = 3.5mm
  • Digital optical fiber
  • 10m range max
RJ11
  • Registered Jack #11
  • Telephone connection
  • 6P2C (6 positions, 2 wires used)
RJ45
  • Registered Jack #45
  • Ethernet connection
  • 8P8C (8 positions, 8 wires used)
Thunderbolt
  • Based on mini displayport
  • Data and power on same cable
  • Daisy chain up to 6 devices
  • V1: 10 Gb/s per channel, 20Gb/s total
  • v2: 20 Gb/s
  • v3: 40 Gb/s
  • Copper max range is 3 meters
  • Optical max range is 60 meters
MIDI – Musical Instrument Digital Interface

Wireless

Infrared
  • IrDA
  • 4Mb/s Line of sight
  • 1 meter max range
  • Found in laptops, phones, cameras, remote controls
NFC – Near field communication
  • 106 kb/s, 212 kb/s, 424 kb/s
  • Range of 10 cm (3.9 in) or less
  • Used in mobile devices and payment devices
Bluetooth
  • Class 1 – industrial, 100mW, 100m range
  • Class 2 – mobile devices, 2.5mW, 10m range
  • Class 3 – Short range use, 1mW, 1m range
  • Version 1.2 – 1 Mb/s
  • Version 2.0 + EDR (Enhanced Data Rate) – 3 Mb/s
  • Version 3.0 + High speed – 24 Mb/s
  • Version 4.0 + Low power – 24 Mb/s
802.11 Networking
StandardFrequencyRateRange
802.11a5 Ghz54 Mb/s120 meters
802.11b2.4 Ghz11 Mb/s140 meters
802.11g2.4 Ghz54 Mb/s140 meters
802.11n2.4 Ghz or 5 Ghz600 Mb/s
(4 channels 150Mb/s)
250 meters
802.11ac5 Ghz693 Gb/s
(8 channels 866.7 Mb/s)
250 meters

Frequency – number of cycles/second (measured in hertz)

1.8 – Computer Power

  • PC power connectors
    • 20 and 24 pin main power
    • Provides 3.3V, 5V, and 12V
    • 20 pin for original ATX, 24 pin added for PCIe
    • 24 pin will fit 20 pin mobo
  • SATA Power
    • 15 pin power connector
    • 3.3V (rare), 5V, and 12V
  • Molex
    • 4 pins
    • Provides 12V and 5V
    • Used to power storage devices, drives, fans, other peripherals
  • 4 pin ATX
    • 12V (ATXV12, P4, or cpu label)
  • 8 pin EPS
    • 12V connector, provides 12V to multiple CPUs
    • Mostly on servers
    • 4+4 connector, not the same as PCI express
  • PCIe 6+2 pin and 12 pin
    • Often 6+2 pins
    • 6 pin 75W
    • 8 pin 150W
    • Additional power for PCIe adapters
    • Primarily for GPUs

PSU Specs

  • To identify the size of the PSU you need, just add the watts of every device you want to connect and double the result
  • Modular PSUs are easier to work with to keep unnecessary cables connected
Amp
  • Rate of electron flow per second
Voltage
  • Electrical “pressure” pushing the electrons
Watts
  • Volts * Amps
AC – Alternating Current
  • Great long range efficiency
  • NA: 110–120 volts and 60Hz
  • Europe: 220–240 volts and 50 Hz
DC – Direct Current
Voltage Rails
  • Single Rail
    • One 12 volt rail power supply
  • Multiple Rails
    • Each output on PSU has separate 12v rail
    • Additional protection from multiple rails
    • Overloads won’t smoke up

1.9 – Computer Configurations

  • Computers aren't one size fits all
  • Learn how to build and configure computers based on specifications of use
  • Different computers include, workstations, graphics workstations for editing, virtualization workstations, specialized PCs like meda based computers, and more

1.10 – Display Devices

  • LCD – Liquid Crystal Display
    • Light shines through liquid crystals
  • TN – Twisted Nematic
    • Most common
    • Low power
    • Fast response time for games
    • Poor viewing angle
  • IPS – In plate Switching
    • Excellent color representation
    • More expensive than TN
  • Backlighting
    • CCFL
      • Cold Cathode Fluorescent Lamp
      • High V
      • Thick
      • Converts power
    • LED backlit LCD
      • LEDs light the display
  • Plasma
    • Tiny cells with noble gas and mercury
  • Digital Projectors
    • LCD are common
    • Metal projectors can have a halide lamp
  • OLED
    • Organic LEDs
    • Thinner and lighter, no glass needed
    • No backlight
    • Short life, fades over time
  • Display specs
    • Refresh rates
      • Number of times a screen is redrawn
      • Measured in hertz (Hz)
    • Resolution
      • Number of pixels (W x H)
      • Standard 4:3 (1600 x 1200)
      • Widescreen 16:10
      • HD 16:9
    • Wireless and Bluetooth antennas often wind around the display

1.11 – Connector Types

  • Out of all connector types inside the case and out, you should be able to identify what the connection is by the shape
  • They won't always be labeled
  • These can be, data, audio, video, and power cables
  • A good test is to look on the back of your motherboard at the I/O backplate and identify each connection
  • It doesn't stop there, know there are adapters and converters that you can use to connect the aforementioned cables to external peripheral devices

1.12 – Computer Peripherals

  • Know about popular input devices like keyboards, mice, scanners, controllers, sensors, smartcards, microphones, webcams, and more
  • Know about popular output devices like speakers, printers, monitors, etc.
  • Know that peripherals do not have to directly connect to a computer and may have limited input and output options
  • Also know how these devices connect to your computer

1.13 – SOHO Multifunction Devices

  • The biggest thing to keep in mind is how multifunction devices can print, scan, fax, copy, and connect to the network.
  • Think of connections, printer drivers, and usage considerations

1.14 – Printers

Laser Printers

  • Uses lasers
  • High voltage
  • High quality
  • Very fast
Imaging Drum
  • Painted with a laser
  • Picks up toner and transfers to paper
Fuser Assembly
  • Melts plastic toner permanently to paper
Colors
  • Cyan, Yellow, Magenta, Black
  • 4 separate toner cartridges
Pickup Rollers
  • One page at a time
  • Periodically needs cleaned
Separation Pads
  • Pulls just top sheet of paper
Duplexing Assembly
  • Prints to both sides of paper

Process

  1. Processing
    • Ready to print full page at one time
  2. Charging
    • Wire set negative charge to photosensitive drum
  3. Exposing
    • Laser writes image to photosensitive drum
  4. Developing
    • Toner applied to drum
  5. Transferring
    • Toner placed on paper from drum
  6. Fusing
    • Heat and pressure to make toner permanent
  7. Cleaning
    • Toner off drum

Inkjet Printers

  • Inexpensive
  • Quiet
  • High resolution
  • Expensive ink
  • Ink cartridges places drops of ink on pages
  • Colors CYMK
    • Cyan, Yellow, Magenta, Key (black)
  • Printhead
    • Integrated into the cartridges, some do not
  • Feed rollers
    • Feeds paper, some duplex
  • Cartridge and belt
    • Moves cartridges over paper
  • Calibration
    • Aligns nozzles to paper

Thermal Printers

  • Receipt printers
  • White paper turns black when heated
  • Very quiet
  • Paper sensitive to light and heat
  • Heating element heats up parts of paper form characters
  • Paper covered with chemicals that changes color with heat

Impact Printers

  • Dot Matrix
  • Printhead has pins that press against paper and mark
  • Good for carbon copies, multiple copies
  • Low cost
  • Noisy
  • Poor graphics, mostly for numbers and letters
  • Paper is pulled through with holes on each side of it
  • Print head
    • Moves back and forth
    • Ribbon in between head and paper
  • Ribbon
    • Made of fabric
    • Easy to replace

Virtual Printers

  • No physical output
  • Sending information a digital file
  • Print to file
    • Basically saving to a file
    • Can only be read by certain programs
  • Print PDF
    • Portable Document Format
    • Cross platform compatibility
  • Print to XPS
    • XML paper specification
    • Similar to PDF, but included with Windows
  • Print to image
    • Letter imaging or sharing
    • Not integrated with OS

1.15 – Printer Maintenance

Laser Printers

  • Kits that include new rollers, fuser units, etc.
  • Check page count to determine maintenance need
  • Do calibration
  • Clean dust from toner

Thermal Printers

  • Clean heating element with alcohol
  • Remove tiny bits of paper
  • Print head pops out with lever

Inkjet Printers

  • Print heads need cleaned
  • Can be done automatically or manually

Section 2: Networking

2.1 – Cables and Connectors

  • ST connectors
    • Straight Tip connector
  • SC connectors
    • Subscriber
    • Square
    • Standard Connector
  • LC connector
    • Lucent
    • Local
    • Little Connector
  • RJ 11
    • 6 position, 2 conductor (6P2C)
    • Telephone connector
  • RJ45
    • 8 position, 8 conductor (8P8C)
    • Modular
    • T568A and T568B need to be the same termination on both sides
  • RJ48C
    • 8P4C
    • T1
    • WAN
    • Data lines
  • BNC connectors
    • Coaxial cable connector
    • Rigid and hard to work with
    • DS3 WAN links
  • F connector
    • Used on coax cables

2.2 – Cable Characteristics

Network Cabling

Fiber Optic
  • Uses light instead of RF
  • Hard to monitor or tap
  • No electromagnetic interference (EMI)
Multimode Fiber
  • Short range, up to 2Km
  • Inexpensive light source (LED)
Singlemode Fiber
  • Long range, up to 100Km without processing
  • Expensive light source (laser beam)
Twisted Pair Copper Cabling
  • Two wires with equal and opposite signals
  • Pairs with different twist rates
  • Twists help with interference
UTP
  • Unshielded twisted pair
  • Most common
STP
  • Shielded twisted pair
  • Protects from interference
  • Needs grounding
Plenum Rated Cable
  • Special cable jacket to minimize smoke during fire
Coax
  • Two or more forms share a common axis
  • RG6 – used for tv
  • RG59 – used as a patch cable (not for long distance)

Calculating Signal Loss

  • Distance = signal loss
  • Attenuation = loss of intensity of signal
  • Decibel (1/10 of a bell) = signal strength ratio measurement
Cable CategoryEthernet StandardMax Distance
CAT310BASE–T100 meters
CAT5100BASE–TX
1000BASE–T
100 meters
CAT5e100BASE–TX
1000BASE–T
100 meters
CAT610GBASE–T37–55 meters
CAT6A10GBASE–T100 meters
CAT7 SHIELDED10GBASE–T100 meters

2.3 – TCP/IP

IPv4 and IPv6

  • IPv4
    • 32 bit address
    • 4 octets with 8 bits each
    • Max decimal value is 255
  • IPv6
    • 128 bit address
    • First 64 network prefix, last 64 host address
    • Hexadecimal
    • IPv6 link local address is required on every IPv6 interface
    • IPv6 compression rules
      • Remove leading 0’s and 2 or more groups of 0’s
      • 2200:0ab0:0000:0000:0000:0000:00b0:0001
      • 2200:ab0::b0:1
RFC1918 Addresses

Private Addresses

RangeMaskHost Size
10.0.0.0 – 10.255.255.255255.0.0.024 bits
172.16.0.0 – 172.31.255.255255.240.0.020 bits
192.168.0.0 – 192.168.255.255255.255.0.016 bits
Automatic Private IP Addressing (APIPA)
  • Used if DHCP is not working
  • Assigned by a workstation server
  • Range: 169.254.0.1169.254.255.254
  • First and last 256 addresses reserved
  • Usable range: 169.254.1.0169.254.254.255
  • Auto assigned: ARP to confirm address not in use

TCP/IP addressing

IP Address
  • Every device needs a unique IP
Subnet mask
  • Used by local workstation to determine what subnet it is on
Default Gateway
  • Allows you to communicate outside local network
DNS
  • Translates domain names to ip addresses
  • Many DNS servers
  • 13 root server clusters
  • Hundreds of generic top level domains (.com, .net, .org, .edu)
  • Over 275 country code top level domains (.us, .ca, .uk)
  • IPs of DNS servers provided by admins
  • Two addresses for redundancy
DHCP
  • Auto assigns IPs
  • Configures IP
  • Subnet mask
  • Default gateway
  • Separate from DNS
  • IPs used to be static
Classless Subnetting
  • CIDR – Classless Inter–Domain Routing
  • Noted as slash at end of IP
MaskCIDR
255.0.0.0/8
255.255.0.0/16
255.255.255.0/24

2.4 – Ports and Protocols

Common TCP/UDP Ports

ProtocolPortNameDescription
FTPTCP/20
TCP/21
File Transfer Protocolsend/receive files between systems
SSHTCP/22Secure ShellEncrypted console access
TelnetTCP/23Telecommunications networkInsecure console access
SMTPTCP/25Simple mail transfer protocolTransfer email between mail servers
DNSUDP/53 TCP/53Domain Name ServiceConvert domain names and IP addresses
HTTPTCP/80Hypertext Transfer ProtocolWeb server communication
POP3TCP/110Post office protocol V3Receive email into an email client
IMAP4TCP/143Internet message access protocol V4A newer email client protocol
HTTPSTCP/443Hypertext transfer protocol secureWeb server communication with encryption
RDPTCP/3389Remote desktop protocolGraphical display of remote access
NETBIOSUDP/137NetBIOS name serviceRegister, remove, and find Windows services by name
NETBIOSUDP/138NetBIOS datagram serviceWindows connectionless data transfer
NETBIOSUDP/139NetBIOS session serviceWindows connection oriented data transfer
SLPUDP/427 TCP/427Service Location ProtocolFind MAC OS services by name
SMBTCP/445Server message blockWindows file transfers and printer sharing
AFPTCP/548Apple filing protocolMAC OS File transfer
LDAPTCP/389 UDP/389Directory service protocolWindows active directory

Port and Protocol Basics

TCP – Transmission Control Protocol
  • Connection oriented
  • Reliable delivery
  • Station
  • Responds back acknowledging receipt of data
  • Can manage out of order messages
UDP – User Datagram Protocol
  • Connectionless
  • No formal setup
  • Data just sent
  • Unreliable, no acknowledgement of receipt
  • No reorder of data, received as is

4 things needed to communicate:

  • Server IP and port number
  • Client IP and port number

Example: 192.168.1.1:62315 –> 182.168.1.2:22

Ports
  • Non–ephemeral ports
    • Permanent port numbers
    • Usually on a server
  • Ephemeral port
    • Temporary port numbers
    • Client side
  • Port numbers can be TCP or UDP
    • Range from 0 – 65,536
    • 0–1024 are well known ports (servers)

2.5 – Wireless Networking

Wireless Standards

  • Wireless networks – IEEE 802.11
  • Popular standards – a, b, g, n, ac
StandardFrequencyStreamsMax Throughput (Stream)Notes
802.11a5 GHz154MB/sSmaller range than b because high frequency (5GHz) is absorbed rather than bouncing like 2.4 GHz
802.11b2.4 GHz111MB/sBetter ranger than a, more frequency conflicts (microwaves)
802.11g2.4 GHz154MB/sBackwards compatible with b, same frequency conflicts as b
802.11n5 and 2.4 GHz4150MB/s
600MB/s
Multiple inputs, multiple outputs (MIMO)
802.11ac5 GHz8866.7MB/s
6934 MB/s
 

Wireless Encryption

WEP – Wired Equivalent Privacy
  • 64 bit or 128 bit key size
  • Very vulnerable, capture enough packets and you can get key
WPA – WiFi Protected Access
  • Larger encryption hash
  • RC4 with TKIP (Temporary Key Integrity Protocol)
  • Every packets gets a unique encrypted key
WPA2
  • Uses AES (Advanced Encryption Standard)
  • CCMP replaces TKIP
  • WPA2 Enterprise
    • Everyone has their own key

2.6 – Configuring a SOHO Router

Wireless Channels and Encryption
  • WPA2 over WPA
  • Never use WEP
  • Not all devices compatible with WPA2, may need upgrade devices
  • Use an open frequency, some APs do automatically for interference
Configuring NAT
  • Automatic on SOHO routers
  • Internal IPs translate to external IP(s)
Port Forwarding
  • 24/7 access to an internal hosted service (Plex, web servers)
  • External IP:port maps to internal IP:port
    • Also called destination NAT or static NAT
    • Does not expire
Port Triggering
  • Like port forwarding, but only under certain circumstances
  • Opens for game, closes when game is turned off
  • Only one person can trigger at a time
IP Addressing
  • Most use DHCP
  • IPs are easy to see on open network
Firewall and DMZ ports
  • Every SOHO router is a firewall
  • No external device can directly access network
  • DMZ ports can allow unrestricted access
    • This is a bad idea for everything on network
Managing QOS
  • Change priority of traffic (VOIP high, streaming low)
  • Prioritize apps, could slow down apps
Firmware Updates
  • Doesn't happen often as it should
  • Usually it's not a good idea flat out upgrade unless there's need or you're technically capable of doing it
  • Save backup of old firmware
UPnP
  • Devices find other devices automatically
  • Auto port forwarding
  • No approval needed so it's a security risk
  • Can make changes to firewall

2.7 – Internet Connections

Internet Connection Types

Cable Modem
  • Data over cable
  • Multiple services
  • DOCSIS – Data Over Cable Service Interface Specification
    • International telecommunications standard that permits the addition of high–bandwidth data transfer to an existing cable TV (CATV) system
DSL
  • ADSL – Asymmetric Digital Subscriber Line
    • 1.5 Mb/s
    • Uses phone lines
    • Download faster than upload (asymmetric)
  • VDSL
    • Very–high–bit–rate DSL
    • 7 Mb/s
Dial up
  • Voice telephone lines
  • 56k modems
  • Slow throughput
  • Analog lines
Fiber
  • High speed
  • Voice and data over line
  • Hundreds of HD channels
  • 1 Gb/s internet, 1 TB cloud, 2 TB DVR
Satellite
  • 2 GHz range
  • high cost
  • 15 Mb/s download, 2 Mb/s upload
  • Sensitive to weather
  • High latency
ISDN – Integrated Services Digital Network
  • Used on legacy telephone systems
Cellular Networks
  • Separates land into cells
  • Antenna covers cell with certain frequencies
  • Tethering turns your phone into a router
LOS
  • Line of sight
  • Visual path between 2 antennas
  • High frequencies
  • Common in metropolitan areas
WI–MAX – Worldwide Interoperability for Microwave Access

Network Types

LAN – Local Area Network
  • Could be one building or a group of buildings
  • Usually high speed
  • Ethernet or 802.11 (wireless)
WAN – Wide Area Network
  • Larger than LAN
  • Communicating across country or world
  • Usually slower than LAN
  • Different types of connections (point to point, satellite)
MAN – Metropolitan Area Network
  • Larger than LAN
  • Smaller than WAN
  • Usually in city, common to see owned by government
PAN – Personal Area Network
  • Bluetooth
  • IR
  • NFC

2.8 – Network Devices

Hub
  • Called a multiport repeater
  • Traffic repeated from one port to all ports
  • 10 megabit, 100 megabit variations
  • Hard to find today
Switches
  • Bridging done in Application Specific Integrated Circuits (ASIC)
  • Forwards traffic based on destination address
  • Core of enterprise networks
  • Multi–layer switches refer to switching and routing capabilities (layer 2 and 3)
Routers
  • Routes traffic between IP subnets
  • Forwarding decisions based on IP addresses
  • Routers inside of switches sometimes called “layer 3 switch”
  • Can connect different types of networks (LAN, WAN, copper, fiber)
WAP – Wireless Access Point
  • Acts as a bridge
  • Extends the wired network onto the wireless network
  • Forwards based on mac address
Modem
  • Modulator/demodulator
  • Converts analog to digital
  • Uses phone lines
Firewalls
  • Integrated into wireless routers or on a standalone device
  • Can proxy traffic
  • Can filter traffic based on TCP/UDP port number
  • Can be a router
  • Can filter based on data in packets
  • Some have VPN capabilities
Patch Panels
  • Combo of punch down blocks and RJ45 connectors
  • Permanent setup
Copper Line Drivers or Extender
  • Extends range of copper or copper ethernet
PLC
  • Power line communication
  • Ethernet over powerline
  • 500 MB/s
PoE
  • With switch – endspan
  • With injector – midspan
  • Mode A – power on data pairs
  • Mode B – power on spare pins

2.9 – Networking Tools

Cable Crimpers
  • Pinches connector to wire
  • Metal prongs pushed in insulation
  • Exact modular connector for type of wire
Multimeters
  • Read voltage, ohms, current
Toner Probe
  • Finds other end of wire
  • Tone generator
    • Puts an analog sound on the wire
  • Inductive probe
    • Does not need to touch wire
  • Hear sound through a small speaker
Cable Testers
  • Continuity checks
  • Identifies missing pins or crossed wires
  • Not used to test frequencies
Lookback Plugs
  • Used for testing physical ports
  • Serial, RS232, network connections
  • Not used for crossover cables
Punchdown Tools
  • Punch a wire into a wiring block
  • Tedious, trims wire during punch
Wireless Analysis
  • Easy to monitor
  • Identifies errors and interference
  • Purpose built hardware or mobile device add on

Section 3: Mobile Devices

3.1 – Laptop Hardware

Expansion Options
  • Express cards – 34mm and 54mm
  • External slotted expansion
  • SB2: 48 Mb/s
  • USB2 bus: 480 Mb/s
  • USB3 bus: 5 Gb/s
  • PCIe bus: 2.5 Gb/s
SO–DIMM – Small Outline Dual Inline Memory Module
  • 64mm x 32mm
  • DDR and DDR2 – 200 pin
  • DDR3 – 204 pin
USB Flash Drive
  • EEPROM – Electrically Erasable Programmable ROM
  • Limited number of writes
  • Nonvolatile
Thunderbolt
  • Same as mini displayport
  • Provides high speed data
Smart Card Reader
  • Security card reader built into the laptop

Replacing a Desktop with a Laptop

Laptop keyboards have less keys than desktop keyboards.

  • Storage – 2.5” and 1.8” drives
  • SSHD – flash memory and spinning disks
  • Laptop and mobile memory – SO–DIMM and Micro DIMM
  • Smartcard readers – integrated or USB
  • Optical Disks – becoming more rare
  • Wifi Cards – PCIe and mini PCI
  • Screens – LCD, fixed resolution, very fragile
  • Power adapter converts AC to DC
  • Batteries – Lithium ION or Li–ion, charging diminishes battery life
  • Laptop frames – heavy duty plastic or metal
  • Motherboards – built to fit certain models, not easy to replace
  • CPU – designed for mobility
    • Integrated features (memory controller, video)
    • Not easily upgradeable

3.2 – Laptop Displays

  • LCD – Liquid Crystal Display
    • Light shines through liquid crystals
    • Requires backlight
    • Inverter converts DC to AC
    • Image but no light may be bad inverter
  • TN – Twisted Nematic LCD
    • Fast response for gaming
    • Low power
  • IPS – In plate Switching
    • Excellent resolution
    • More expensive
  • Fluorescent backlight
    • Higher voltage
    • Added thickness
  • LED backlight
    • LEDs around edge of screen
  • OLED – Organic LED
    • No backlight
    • Degrades overtime
    • Expensive
  • WiFi antennas
    • Wires wrap around outside of LED display
    • Main and auxiliary wire
  • Webcam
    • Audio and video

3.3 – Laptop Features

Function Key
  • Fn + key
  • Some are toggleable
  • Example Uses: volume, screen brightness, airplane mode, enable or disable touchpad, screen orientation, gps, media options, and more
Docking Stations
  • Laptop slides into device to connect to mouse, keyboard, and other devices

3.4 – Mobile Devices

  • Tablets – 7” or longer
  • Smartphones – 3.5” – 5.5”
  • Phablet – 5.5” to 7”
  • E–readers – books plus music and other media
  • Smart Camera – face recognition and other features

3.5 – Mobile Device Accessories

Mobile Device Communication

NFC – Near Field Communication
  • You can send small amounts of data over a limited area
  • Built into phone
  • Used for payment systems, transportation, access tokens, and identity cards
  • Short range with encryption
Proprietary Mobile Interfaces
  • Early phones have power cable and a separate cable for data
  • EU set a standard on USB
  • Micro USB standard, common worldwide
  • Other devices use mini USB
  • Apple has lightning cable
    • Higher power output
    • Inserted either way
    • More durable
Bluetooth
  • Personal Area Network (PAN)
IR
  • Used to control other IR devices, like phone for TV remote
Hotspot/Tethering
  • Phone acts as 802.11 WAP

Mobile Device Accessories

  • Headsets – wired used TRRS connector (Tip Ring Ring Sleeve)
    • Wireless used Bluetooth
  • TRRC – allows the use of a microphone
  • Speakers – wires or Bluetooth
  • External Game Pads – game controllers for mobile
  • Docking Stations – no wires, charge and sync
  • Credit Card Readers – phone becomes Point of Sale terminal
    • Uses internet link for approvals
    • Email receipt, sign with finger
    • SD/MicroSD

Section 4: Hardware and Network Troubleshooting

4.1 – Troubleshooting Computer Hardware

Unexpected Shutdowns
  • Could be heat related
  • Check temps, heatsink, fans
Overheating
  • Heat from CPUs, video cards, dust build up
  • Clean dust, check fans, airflow, heatsink,
Failing Hardware
  • Run hardware diagnostics
Lockups
  • Computer freezes up
  • Check for activity (HDD light, status light)
  • CTRL + ALT + DEL
  • Update drivers
  • Low resources such as RAM or storage
Hardware Diagnostics

POST

  • Power on self test
  • Tests major components
  • Beep codes for failures
  • Every manufacturer has unique beep codes
Blank Screen
  • Bad video
  • Listen for beeps
  • BIOS issue
Continuous Reboots
  • How far is the boot going?
Bad Driver Configuration
  • Boot with F8 in safe mode
  • Select last known good configuration
No Power
  • Check power source
  • No POST could be bad motherboard
  • Check power supply output
Loud Noises
  • Rattling – loose components
  • Scrapping – HDD issue
  • Clicking – check fans
  • Popping or smoke – check capacitors
Intermittent Device Failure
  • Bad install, reseat
  • Could be bad hardware
Indicator Lights
  • POST codes on motherboard
  • Power, link light, speed light, HDD
Smoke and Burning Smell
  • Electrical issue, remove power
BSOD
  • Windows crash, Windows stop error
  • Check event log for clues
Spinning Ball of Death
  • Apple computer issue
  • Bug or hardware issue

Hardware Troubleshooting Tools

  • DMM – check voltage, continuity
  • Power supply tester – plugs in power supply, LCD shows voltage
  • Loopback Plugs – useful for testing physical plug, serial/RS232 (9 or 25 pin)
  • Port card/USB – detailed diagnostics during POST, LED numbers and letters

4.2 – Troubleshooting Storage Devices

  • Read/write failures
  • Slow performance – constant LED activity
  • Loud clicking noise – mechanical issue
  • Troubleshooting – backup, check cables, check for heat, check PSU, diagnostic
  • Boot failure – drive not recognized, beeps, error messages
  • NO OS – HDD seen but Windows not seen, check boot order
  • RAID not found – missing or faulty raid connector, check raid software
  • Crash screens – may indicate bad HDD
  • S.M.A.R.T. – Self monitoring, Analysis and Reporting Technology
    • Monitors how drive is operating
    • Uses 3rd party utilities, finds warning signs

HDD Troubleshooting Tools

  • Physical Tools – screw drivers and external disc enclosures
  • CHKDSK /f – finds errors and repairs them
  • CHKDSK /r – locates bad sectors and recovers, also does /f
    • If volume is in use, run at startup (/r and /f)
  • Format – Windows command, adds a file system a partition
    • Also removes all file entries
  • File recovery software – recovers files if not overwritten
  • Defragmentation – moves files fragments so they are contiguous
    • Not necessary for SSD, defrag on cmd

Troubleshooting Boot Process

  • PC only knows the basics: keyboard, mouse, RAM, etc.
  • Bootstrap Loader – In BIOS, loads program that loads the OS
  • 2nd stage Boot loader – winload, GRUB, legacy
    • Gets the OS Started
  • Master Boot Record (MBR)
    • First sector of the HDD
    • Usually only 512 bytes
    • Contains table of primary partitions
    • Contains disk signature and directions to starting OS
    • EFI does not use MBR, EFI System Partition (ESP)
  • Windows Command Prompt
    • Boot from install disc to access CLI
    • Very powerful, last resort
    • Complete control, modify OS files
    • Enable / disable service or device startup
    • Repair system boot sector or MBR
  • BOOTREC command
    • BootREC /scanOS – identifies Windows OS
    • BootREC /fixboot – writes a new boot sector
    • BootREC /rebuildBCD – creates new boot config data store
  • DISKPART – manage partitions

4.3 – Troubleshooting Display Issues

  • No video connection
    • First check everything is connected
    • No video after Windows boot, use VGA mode (F8)
  • Image Quality Issue
    • Check cables, pins, and interfaces
  • Distorted
    • Check OS refresh rate and resolution
    • Disable hardware acceleration
  • Oversized Images
    • Resolution too low, lower = larger
  • Image Sticking
    • Problem with LCDs, white screen to refresh
  • Pixel Issues
    • Stuck pixels = always bright
    • Dead pixels = always black
  • Artifacts
    • Unusual graphics, check adapters and drivers
  • Motion trails
    • Disable advanced video features
  • BSOD and overheating
    • Video drivers
    • Monitor internal temp

4.4 – Troubleshooting Networks

  • No network connection
    • Check lights on physical connection
    • Ping loopback 127.0.0.1
    • Ping local IP address
    • Ping default gateway
    • Ping devices outside local network
  • Automatic Private IP addressing (APIPA)
    • Link local address
    • Communicates inside local subnet
    • 169.254.1.0169.254.254.255
    • 169.254.0.0/24 and 129.254.25.0/24 are reserved
    • Automatically assigned, when DHCP unavailable
    • Uses ARP to confirm address not in use
  • Limited or no connectivity
    • Check local IP, make sure APIPA not used
    • If DHCP is in use, do PING tests
  • Intermittent connectivity
    • Check system tray, check cables and NIC
    • Check switch or WAP
  • IP conflicts
    • Two devices cannot used same IP
    • DHCP helps, statics can cause issues
    • Windows will identify duplicates and prevent issues
    • Reboot or reset NIC to restart DHCP process
  • Slow transfer Speeds
    • Overloaded network or devices
    • Speed and duplex must match
    • Hardware issue or cabling
    • Also could be malware infection
  • Low RF wireless signal
    • Interference with devices on same frequency
    • Incorrect channel, usually automatic
    • Bounce and latency
    • WAP location
  • Wireless interference
    • Fluorescent lights, microwaves, cordless phones
    • High power sources, multi tenant buildings
  • SSID not found
    • Could be too far away, closer networks could be louder
    • SSID could be hidden, must enter manually

Network Troubleshooting Tools

  • Cable tester – continuity checks, crossed wires
  • Loopback plug – tests physical ports, serial/RS232, RJ35, T1
    • Only used for diagnostics
  • Punchdown Tools – punches wire into block, 60 and 110 blocks
    • Trims wires, makes neat, must maintain twist
  • Toner Probe
    • Finds where cable goes
    • Generator puts analog sound signal on wire
    • Probe does not need to touch, sound through speaker
    • Used on punchdown blocks
  • Crimpers – pinches connector onto wire
    • Metal prongs pushed through insulation
  • Wireless Locators –  software or hardware
    • Shows network frequencies, channels, etc.

Command Line Troubleshooting

  • PING
    • Tests reachability and round trip time
    • Uses ICMP
    • Primary a troubleshooting tool
  • IPCONFIG
    • Used in Windows
    • IP info, DNS, default gateway, etc.
  • IPCONFIG /all
    • Much more info
  • IFCONFIG
    • IPCONFIG in Linux
  • TRACERT
    • Determine route packet takes to destination
    • Tracert – Windows
    • Traceroute – Linux
    • Uses ICMP TTL
    • TTL= time to live = number of hops
    • Decreased by 1 everytime packet goes through router
    • Not all devices will reply with ICMP
    • Some firewalls block ICMP
  • NETSTAT
    • Network statistics
    • Netstat –a = shows all active connections in and out PC
    • Netstat –b = shows binaries
    • Netstat –n = do not resolve names, only show IPs
  • NBTSTAT
    • Netbios over TCP/IP
    • Windows utility for querying netbios over TCP/IP info
    • Nbtstat –n = list local netbios names
    • Nbtstat –A 192.168.1.1 = list remote netbios names and IPs
  • NET
    • Windows network commands
    • NET stop: stop a service (net stop spooler)
    • NET start: start a service (net start spooler)
    • NET use: map a network share to drive letter (net use h:\<servername> \ <sharename>)
    • Net view: view network resources (net view \\<servername>)
  • NETDOM
    • Manage AD, Windows 8 and higher
    • Used to join PC to domain, remove account, view domain info
  • NSLookup
    • Lookup info from DNS servers, Windows, Mac and Linux

4.5 – Troubleshooting Mobile Devices

Troubleshooting Laptops

  • No display or dim – verify backlight,
  • No light = replace inverters
  • External Display – video good but bad LCD, replace LCD
  • Flickering Video – check cables and connectors
  • Input issues – laptop keyboards more fragile
  • Ghost Cursor – modify configuration, update drivers
  • Wireless troubleshooting – check antenna cables, multiple cables
  • Power issues – battery not charging, batteries lose capacity over time
    • No power = check outlet
  • Master laptop reset – hold power button for 10 seconds
  • External Monitor Issues – Fn keys to toggle LCD, CRT
    • External monitor bypassed LCD (uses hardware)

Troubleshooting Mobile Devices

  • Unresponsive Screen
    • Could be software issue, do a reset
    • Apple iOS
      • Power, slide, power button
      • Hold power and home for 10 seconds
    • Android
      • Remove and reinstall battery
  • APP issues
    • Not loading or slow, reset app
    • iOS
      • Double tap home, slide app up
    • Android
      • Settings, apps, select app, force stop
  • Unable to decrypt Email
    • Encryption built into email system
    • Each user has a private key
    • Mobile device manager for private keys
  • Short battery life
    • Bad reception, always searching for signal
    • Airplane mode to fix that
    • Disable unnecessary features, check app usage
    • Replace aging batteries
  • Overheating
    • Phone will shut down automatically to prevent damage
    • Causes include charging, CPU usage
    • Avoid direct sunlight
  • Frozen Systems
    • Nothing works, do a soft or hard reset
    • Ongoing issue may require factory reset
  • No sound from speakers
    • Check volume settings (also in app)
    • Reinstall software, try headphones
    • Intermittent could be conflicting with other app
    • No sound = factory reset
  • GPS not working
    • Enable GPS and location services, need good sky view
  • Swollen Battery
    • Buildup of gas, designed to self contain
    • Stop using immediately
  • Device Disassembly
    • Much harder than desktops, hard to reassemble
    • Fragile
    • Document where parts go, cable locations
    • Use organizer for screws and other parts
    • Step by step take picture
    • Anti–static important, tinier tools than desktop

4.6 – Troubleshooting Printers

  • Test printer
    • Print or scan a test page
    • Build into Windows, not printer app
    • Diagnostic tools
  • Bad output
    • Inkjet– clean print heads
    • Laser – check for scratched drum
  • Faded or blank
    • Low toner or ink
  • Ghost images
    • Drum not cleaned properly
    • Shadow of previous rotation
  • Wrong color
    • Low ink in one cartridge
  • Smudges
    • Toner now fused to paper
    • Fuser may not be hot
  • Paper Jam
    • Do not rip paper out, could damage components
  • Not feeding
    • Check rollers
  • Creased paper
    • Paper loading incorrectly or wrong type of paper
  • Printer Network Issues
    • No connectivity – check power, wired cabling or wireless settings
  • Access denied
    • Check security tab, print, manage printer, manage docs
  • Bad output – garbled characters
    • Bad drivers / wrong model
    • Wrong page description language (PCL or postscript)
    • Bad app, check test page
  • OS issue
    • Unable to install printer, check 32 bit or 64 bit requirements
    • User must have proper rights to install
  • Backed up print queue
    • Print server not working
    • Spooler crash
    • Restart spooler (in Windows)
  • Error message
    • On printer LCD screen
  • Low memory
    • Laser printer builds entire page in memory
    • Complex images use more memory
  • No output
    • Check power, run test page (button on printer)
    • Check connectivity, print with attached device (USB)
    • Check network and apps

Printer Troubleshooting Tools

  • Laser printer maintenance kits
    • Laser printers do wear out
    • New feed rollers and fuser unit
    • Check page counter to determine if needed
    • Reset page counter when finished
  • Toner Vacuum
    • Specially made, anti static
  • Outside of printer
    • Use water or IPA
  • Inside of printer
    • Wipe dust away, clean rollers with IPA
  • Printer Spooler
    • Manages printing in the background of Windows
    • Runs as a Windows service
    • Is not always perfect

Conclusion

Whoo boy. That does it. Over 7K words of CompTIA A+ 220-901 goodness. Let me know what was easy for your and of course, what you had trouble with.

If anything needs to be corrected or added, please sound off in the comments below.

Thanks and good luck on the exam!

Update: When you're ready for the next CompTIA A+ exam, head over to the 220-902 exam study notes post to review your stuff. If you need to see the A+ exams overview again, check out that post.

You're almost CompTIA A+ certified!

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