Neko

C393 - IT Foundations (A+ Core 1)

Exam Compass -> Professor Messer -> Dion Practice -> Win.


Last updated: May 4th, 2023

Course Notes

Module 1: Mobile Devices

Laptop Displays

  • Portable LCD
    • Advantages
      • Lightweight
      • Low power consumption
      • Relatively Inexpensive
    • Disadvantages
      • Black level challenges
      • Requires backlight
      • Lights are difficult to replace
    • Backlight Tech
      • CCFL
        • Cold Cathode Fluorescent Lamp
        • Uses mercury
        • Not as efficient as LEDs
      • TN
        • Twisted Nematic
        • Fast response time
        • Low viewing angle
      • IPS
        • In-Plane Switching
        • Excellent Color
        • More Expensive than TN
      • VA
        • Vertical Alignment
        • Compromise between TN and IPS
        • Slow response time
  • OLED
    • Organic Light Emitting Diode
    • Uses organic compounds that emit light when electric current is recieved.
    • Thin and lightweight
    • High contrast
    • No backlight allows true black
  • Inverter
    • Turn DC into AC
  • Digitizer
    • Converts touch input into digital data

Cellular Standards

  • PRL
    • Preferred Roaming List
    • Contains a list of towers that the phone will connect to
  • 2G
    • GSM
      • Global System for Mobile Communications
      • 90% of the global market
      • EU Standard
      • Used by AT&T and T-Mobile
      • Multplexing
    • CDMA
      • Code Division Multiple Access
      • Used by Verizon and Sprint
      • Calls use unique codes
  • 3G
    • Introduced in 1998
    • Better connectivity enabled new functionality
    • Several megabits per second
    • HSPA
    • EVDO
  • 4G
    • LTE
      • Long Term Evolution
      • Introduced in 2009
      • Based on GSM and EDGE
      • Supports 150 Mbps
    • LTE Advanced
      • Supports 300 Mbps
    • 5G
      • Introduced in 2019
      • Supports 10 Gbps
      • IoT impact

Module 2: Networking

Common Ports and Services

  • FTP
    • tcp/20 for data
    • tcp/21 for control
  • SSH
    • tcp/22
  • Telnet
    • tcp/23
  • SMTP
    • tcp/25
    • Server to Server
  • DNS
    • udp/53
  • DHCP
    • udp/67
    • udp/68
  • HTTP
    • tcp/80
  • POP3
    • tcp/110
    • Server to one client
  • IMAP
    • tcp/143
    • Server to multiple clients
  • HTTPS
    • tcp/443
  • SMB
    • tcp/445
    • NetBIOS
      • tcp/137 for name services, registration, removal by name
      • tcp/139 for session services and data transfer
  • SNMP
    • udp/161 for queries/metrics/management
    • udp/162 for responses/traps/alerts
    • V1
      • Structured Table
      • Cleartext
    • V2
      • Enhanced data types
      • Bulk Transfer
      • Cleartext
    • V3
      • Authentication
      • Encryption
  • LDAP
    • tcp/389
  • RDP
    • tcp/3389

Network Devices

  • Routers
    • Connects networks
    • Forward packets based on IP
    • Layer 3
  • Switches
    • Forward packets based on Layer 2 address
    • Multilayer switch includes router functionality
    • Unmanaged Switches
      • Plug and play
      • Fixed Configuration
      • Cheap
    • Managed Switches
      • Supports VLANs
      • Traffic Prioritization
      • SPT redundancy
      • Port mirroring
      • SNMP
  • Hub
    • Connects devices
    • Repeats all traffic to all ports
  • Patch Panels
    • Connects cables to switches
    • Keeps cables organized
  • Power over Ethernet
    • POE
      • IEEE 802.3af - 2003
      • 15.4W DC, 350mA max current
    • POE+
      • IEEE 802.3at - 2009
      • 25.5W DC, 600mA max current
    • POE++
      • IEEE 802.3bt - 2018
      • 51W (Type 3), 600mA max current
      • 71.3W (Type 4), 960mA max current
      • PoE with 10GBASE-T
  • ONT
    • Optical Network Terminal

Network Tools

  • Cable Crimper
    • Strips, cuts, and crimps cables
  • WiFi Analyzer
    • Identifies errors and interference
  • Tone Generator
    • Identifies cable runs using analog sound
  • Punchdown Tool
    • Punches down wires into patch panels
  • Cable Tester
    • Tests for continuity
  • Loopback Plug
    • Useful for testing physical ports
  • Taps and Port Mirrors
    • Used to monitor and intercept traffic

Software Defined Networking

  • Split the network into 3 layers
    • Control Plane
    • Data Plane
    • Management Plane
  • Control Plane
    • Routing tables
    • Session tables
    • NAT tables
  • Data Plane
    • Process network frames and packets
    • Forward packets
  • Management Plane
    • Configuration
    • Monitoring

Wireless Network Standards

  • 802.11a
    • 1999
    • 5GHz
    • 54Mbps
  • 802.11b
    • 1999
    • 2.4GHz
    • 11Mbps
  • 802.11g
    • 2003
    • 2.4GHz
    • 54Mbps
  • 802.11n (WiFi 4)
    • 2009
    • 2.4GHz and 5GHz
    • 40MHz channel widths
    • 150Mbps per MIMO stream
    • 600Mbps
  • 802.11ac (WiFi 5)
    • 2013
    • 5GHz
    • 160MHz channel widths
    • 867Mbps per MIMO stream
    • 6.9Gbps
    • Eight EU-MIMO downlink streams
  • 802.11ax (WiFi 6)
    • 2021
    • 2.4GHz and 5GHz
    • 20, 40, 80, 160MHz channel widths
    • 1.2Gbps per MIMO stream
    • 9.6Gbps
    • Eight bidirectional Multi-User MIMO (MU-MIMO) streams
    • Orthogonal Frequency Division Multiple Access (OFDMA)

WiFi Channels

  • 2.4GHz
    • 1-11, in the US and Can
    • 1-13, in the EU
    • 1-14, in Japan
    • 1, 6, 11 are the most common
    • b, g, n, and ax
  • 5GHz
    • Not as effective at penetrating walls
    • a, n, ac, and ax

Assigning IP Addresses

  • DHCP
    • Replaced BOOTP in 1997
      • BOOTP was Introduced in 1993
    • APIPA
      • Automatic Private IP Addressing
      • IPs are assigned when DHCP is not available
      • 169.254.0.0/16

DNS

  • Address Records
    • A
      • IPv4
    • AAAA
      • IPv6
  • MX Records
    • Mail Exchanger
  • SPF
    • Sender Policy Framework
    • Prevents spoofing
  • DKIM
    • Domain Keys Identified Mail
    • Digitally sign outgoing mail
  • DMARC
    • Domain-based Message Authentication, Reporting, and Conformance
    • Combines SPF and DKIM

Internet Connection Types

  • DSL
    • Direct Subscriber Line
    • Uses existing copper telephone lines
    • CO (Central Office) - CPE (Customer Premises Equipment)
    • 200Mbps/DOWN, 20Mbps/UP
  • Cable
    • Broadband
    • 50Mbps to 1Gbps
    • Uses insulated and shielded coaxial cable
    • DOCSIS
      • Data Over Cable Service Interface Specification
  • Fiber
    • Higher cost than copper
    • Uses glass or plastic surrounded by a protective coating to transmit light.
    • SONET
      • Synchronous Optical Network
  • Satellite
    • Uses a satellite dish to receive signals from a satellite in orbit
    • High cost
    • Good for remote locations
  • Cellular
    • Uses radio waves sent from a cell towers that are placed in a way to divide the land into cells
  • WISP
    • Wireless Internet Service Provider
    • Need an antenna

Module 3: Hardware

Network Cables

  • Twisted Pair
    • Cat 5
      • 1000Base-T
      • 100 meters
    • Cat 5e
      • 1000Base-T
      • 100 meters
      • Enhanced
    • Cat 6
      • 10GBASE-T
      • Unshielded: 55 meters
      • Shielded: 100 meters
    • Cat 6a
      • 10GBASE-T
      • 100 meters
      • Augmented
    • S
      • Braided Shielding
    • F
      • Foil Shielding
    • U
      • Unshielded
  • Coaxial
    • RG-6 used in TV cable
  • Plenum-rated Cable
    • Fire resistant
    • Flourinated Ethylene Polymer (FEP) or Polyvinyl Chloride (PVC)
  • Optical Fiber
    • No electrical interference, difficult to monitor or tap
    • Single-mode
      • Short-Range; 2km
      • May use LEDs or other inexpensive light sources
    • Multimode
      • Long-Range; 100km
      • Uses lasers

568A and 568B

  • 568A
    1. White/Green
    2. Green
    3. White/Orange
    4. Blue
    5. White/Blue
    6. Orange
    7. White/Brown
    8. Brown
  • 568B
    1. White/Orange
    2. Orange
    3. White/Green
    4. Blue
    5. White/Blue
    6. Green
    7. White/Brown
    8. Brown

Peripheral Cables

  • USB
    • Universal Serial Bus
    • USB 1.0 - 1.5Mbps
    • USB 1.1 - 12Mbps
    • USB 2.0 - 480Mbps
    • USB 3.0 - 5Gbps
    • USB 3.1 - 10Gbps
    • USB 3.2 - 20Gbps
    • USB 3.2 Gen 2x2 - 40Gbps
    • USB 4.0 - 40Gbps
  • DB-9
    • Serial
    • Commonly used as a console port
  • IDE
    • Integrated Drive Electronics
    • Parallel
    • Used for hard drives and optical drives
    • 40-pin

Video Cables

  • VGA
    • Video Graphics Array
    • DE-15
    • 15-pin D-Sub
    • Blue color
    • Analog
    • Degrades after 5 to 10 meters
    • A VGA cable, it has a large bulky blue case that has two twisting locks. The connector is rectangular and has three rows of 5 pins
  • DVI
    • Digital Visual Interface
    • Single Link
      • 3.7 Gbps (HDTV at 60 fps)
    • Dual Link
      • 7.4Gps (HDTV at 85 fps)
    • No audio
    • DVI-A
      • Analog
    • DVI-D
      • Digital
    • DVI-I
      • Integrated
      • Can be analog or digital
    • Similar to the vga in shape and has two twisting locks, the case is black and bulky, the connector has two units with three rows of three pins and to the left of one unit is another longer pin and in between the two units is a collapsed rectangle.
  • HDMI
    • High-Definition Multimedia Interface
    • All digital
    • 19-pin
    • Audio and video
    • Degrades around 20 meters
  • DisplayPort
    • Information is sent in packets
    • Compatible with HDMI and DVI
    • Video and Audio

SATA

  • Serial Advanced Technology Attachment
  • Revision 1.0 - 1.5 Gbps
  • Revision 2.0 - 3.0 Gbps
  • Revision 3.0 - 6.0 Gbps
  • Revision 3.2 - 16.0 Gbps
  • Uses a 7-pin connector for data
  • Uses a 15-pin connector for power
  • Commonly used for storage devices

SCSI

  • Small Computer Systems Interface
  • Some configuration is done by the SCSI

Connectors

  • RJ-11
    • Telephone or DSL
    • 6P2C
    • Used for analog phone lines
  • RJ-45
    • 8P8C
    • Commonly used for Ethernet
  • RS-232
    • Versatile
    • DE-9
    • DB-25
    • It has the two twist things
  • BNC
    • Bayonet Neill-Concelman
    • Used for coaxial cable
    • Twist-lock
  • F-Connector
    • Coaxial
    • Associated with Cable
  • Fiber Connectors
    • ST
      • Straight Tip
      • It has the extended tip
    • SC
      • Subscriber Connector
      • Square
    • LC
      • Latching/Local Connector
      • Often comes in a pair

Memory

  • DIMM
    • Dual Inline Memory Module
    • Used for desktops
    • SODIMM
      • Small Outline DIMM
      • Used for laptops
  • DDR
    • Double Data Rate
  • SDRAM
    • Synchronous Dynamic Random Access Memory
  • Parity Bit
    • In a set of 8 bits, one bit is used to check the other 7 bits
    • It checks if there is an even or odd number of 1s, if odd the parity bit will equal one. If even, the parity bit will remain zero
  • ECC
    • Error Correcting Code
    • High Integrity

Storage

  • AHCI vs NVMe
    • AHCI
      • Advanced Host Controller Interface
      • Move data from the hard drive to RAM
      • Designed for hard drives
    • NVMe
      • Non-Volatile Memory Express
      • Move data from the hard drive to RAM
      • Uses PCIe
      • Designed for SSDs
  • M.2 Interface
    • B-Key
    • M-Key

RAID

  • Redundant Array of Independent Disks
  • RAID 0
    • Striping
    • Fastest
    • Least reliable, no redundancy
    • Does not increase capacity
  • RAID 1
    • Mirroring
    • Slowest
    • High redundancy
    • Requires two drives
  • RAID 5
    • Striping with parity
    • Fast
    • Reliable
    • Requires 3 or more drives
  • RAID 10
    • Striping with mirroring
    • The speed of striping and the reliability of mirroring
    • Requires 4 or more drives

Motherboards

  • Form Factor
    • ATX
      • Best used in servers or desktops
      • Standardised in 1995
      • 20pin or 24pin power connector
      • 8pin or 4pin CPU power connector
    • Micro ATX
      • Commonly used in small desktops
      • Same as ATX but smaller
      • Uses a 20pin power connector
    • ITX
      • Low power
      • Small
      • Compatible with ATX screws
      • Useful for single-purpose computers, such as a media center
  • Expansion Slots
    • Computer Bus
      • Sends data between devices
    • Expansion Bus
      • Connects the motherboard to the expansion cards
      • Width of the bus determines the speed of the data transfer
      • Clock rate is the speed of the bus
    • PCI
      • Peripheral Component Interconnect
      • The PCI bus is a type of expansion bus
      • The PCI slot provides power to cards
      • 32-bit is shorter in length and has less pins than 64-bit pci card/slot
      • PCIe
        • Peripheral Component Interconnect Express
        • Replacement for PCI, PCI-X and AGP
        • Communicates serially using serial lanes (serial experiments lain?)
        • Used for GPUs, RAID controllers, network cards, sound cards, etc
        • PCIe x1
          • 1 lane
          • 1.5GB/s
          • Network Cards
        • PCIe x4
          • 4 lanes
          • 6GB/s
        • PCIe x8
          • 8 lanes
          • 12GB/s
        • PCIe x16
          • 16 lanes
          • 24GB/s
          • Graphics Cards
    • Riser Card
      • Allows cards to be placed in different orientations
  • Connectors
    • CPU Socket
      • Not an easy task to replace
    • ZIF Socket
      • Zero Insertion Force
      • Used for CPUs
      • Has lots of holes for Pin Grid Array (PGA) CPUs
    • LGA Socket
      • Land Grid Array
      • Reverse of PGA
    • Storage Connectors
      • SATA
      • PATA
        • Uses IDE slot

BIOS

  • Navigating to BIOS Settings
    • Del, F1, F2, CTRL-S, CTRL-ALT-S
    • Hold shift when pressing restart in Windows
  • UEFI Secure Boot
    • Verifies the bootloader by checking the signature
  • TPM
    • Trusted Platform Module
    • Crypto processor
  • HSM
    • Hardware Security Module
    • Crypto Hardware, Key Backup, Crypto Accelerator
  • CMOS
    • Complementary Metal Oxide Semiconductor
    • Stores BIOS settings
    • Uses a battery to keep settings when the computer is off
    • Modern systems use a flash memory chip instead

CPU technologies

  • ARM
    • Advanced RISC Machine
    • Power efficient
      • Simpler instruction set
    • Used in mobile and IoT devices
  • Multithreading
    • HTT
    • One CPU acts like two
      • Usually sees a performance increase of 15-30%
    • Most modern OS support this
  • Virtualization
    • Intel VT-x
    • AMD-V

Computer Power

  • Always disconnect a device when working on it
  • If a device stores a charge in a capacitor, it will still have power even when disconnected
  • Power Supply
    • Converts 120V AC or 240V AC to 3.3V DC, 5V DC, 12V DC
  • Amp, Watt, Volt, Ohm
    • Amp = Current
      • How much charge is flowing through a circuit
      • The diameter of the hose
    • Volt = Voltage
      • Electrical pressure
      • How open the faucet is
    • Watt = Power
      • How much energy is being used
      • Watt = Volt * Amp
    • Ohm = Resistance
      • How much resistance there is to the flow of electricity
      • Ohm = Volt / Amp
  • Current
    • AC
      • Alternating Current
      • Current that changes direction
      • US/Canada use 120V AC, 60Hz
      • Europe uses 240V AC, 50Hz
    • DC
      • Direct Current
      • Current that flows in one direction
  • Ground
    • Electrical current flows to ground
    • Ground is a conductor
    • Ground is a reference point
  • Power Supply Output
    • +12V
      • PCIe adapters, hard drives, optical drives, fans
    • +5V
      • Some motherboard components
    • +3.3V
      • M.2 SSDs, RAM slots, logic circuits
    • +5VSB
      • Standby voltage
    • 12V
      • Integrated LAN
      • Older serial ports
    • -5V
      • ISA slots
      • Not used anymore

Multifunction Devices

  • Printers
    • Laser
      1. Processing in memory
      2. Charge drum
      3. Exposing with laser
      4. Add toner to charged areas
      5. Transfer to paper
      6. Fuse with heat
      7. Remove excess toner
      • Pros
        • Fast
        • High quality
      • Cons
        • Complex
        • Moving Parts
      • Image Drum
        • Contains the toner
        • Drum rotates and applies toner to the paper
        • Image is drawn on the drum by the laser
      • Fuser Assembly
        • Melt plastic toner using heat and pressure
      • Transfer Belt
        • Image is transferred from all cartridges to the single belt
        • Cyan, Magenta, Yellow, Black
      • Pickup Roller
        • Rolls the paper through the printer
      • Separation Pad
        • Pulls one sheet from the paper tray
      • Duplexing assembly
        • Prints on both sides of the paper
      • Maintenance
        • Replace toner, low does not mean empty
        • Toner may contain the OPC drum, sensitive to light
        • Printers page counter will tell you when to perform maintenance
        • Clean the printer routinely, the toner and paper dust spreads. Stick to the manufacturers recommendations
    • Inkjet
      • Pros
        • Low cost tech
        • Quiet
        • High resolution
      • Cons
        • Ink is proprietary and expensive
        • Ink Fades
        • Print head clogs
      • Ink Cartridge
        • CMYK
        • Place droplets of ink on the paper
      • Print Head
        • Occasionally the print head will be integrated into the ink cartridge
        • Print head may clog
      • Feed Roller
        • Rolls the paper through the printer
      • Carriage and Belt
        • Carriage moves the print head back and forth
        • Belt moves the carriage
      • Maintenance
        • Replace ink cartridges when they are empty, empty cartridge can be recycled.
        • Jams are inevitable
        • Calibrate the printer routinely
    • Thermal
      • Pros
        • Very Quiet
        • No ink
      • Cons
        • Sensitive to light and heat
      • Thermal Paper
        • Paper changes color when heated
      • Feed Assembly
        • Rolls the paper through the printer
      • Heating element
        • Heats the paper
      • Maintenance
        • Thermal paper measurements differ
        • A cleaning pen and IPA can be used to clean the heating element
    • Impact
      • Pros
        • Low cost per page
        • Good for multiple copies
      • Cons
        • Low resolution
        • Noisy
      • Print Head
        • Moves back and forth, pressing a ribbon against the paper
      • Ribbon
        • One ribbon
        • Proprietary size
      • Maintenance
        • Replace ribbon when ink lightens
        • Print head can be replaced when the ribbon is replaced
    • 3D
      • Filament
        • FDM
          • Fused Deposition Modeling
          • More Common than SLA
          • Uses a heated nozzle to melt plastic
        • SLA
          • Stereolithography
          • Uses a laser to cure a liquid resin
          • Resin is hazardous

Module 4: Virtualization and Cloud Computing

Cloud Deployment Models

  • Public Cloud
    • Resources are shared with the public
  • Private Cloud
    • Resources are shared with a single organization
  • Hybrid Cloud
    • A mix of public and private cloud

Cloud Service Models

  • Software as a Service (SaaS)
    • Software is hosted by the cloud provider
    • Users access the software through a web browser
    • Examples: Google Docs, Office 365
  • Platform as a Service (PaaS)
    • Platform is hosted by the cloud provider
    • Users can develop and deploy their own applications
    • Examples: Google App Engine
  • Infrastructure as a Service (IaaS)
    • Infrastructure is hosted by the cloud provider
    • Users can deploy their own applications
    • Examples: Amazon Web Services

Virtualization

  • Hypervisor
    • Software that creates and runs virtual machines
    • Type 1: Runs directly on the hardware
      • Examples: VMware ESXi, Microsoft Hyper-V
    • Type 2: Runs on top of an operating system
      • Examples: VMware Workstation, VirtualBox
  • Requirements
    • AMD-V or Intel VT-x
  • Security Concerns
    • VM escape
      • VM escapes the hypervisor and gains access to the host
      • Often is done using shared memory, clipboard, drives, etc
    • VM sprawl
      • VMs become unmanageable

Module 5: Hardware and Network Troubleshooting

Troubleshooting

  1. Identify the problem
  2. Establish a theory of probable cause
  3. Test the theory
  4. Create a plan to fix the problem
  5. Implement the plan
  6. Verify the problem is fixed
  7. Document the solution

Hardware Troubleshooting

  • POST
    • Power On Self Test
    • Test major components before boot
    • Beep codes
  • POST and Boot
    • Blank screen on boot
      • Any beeps?
      • Bad video, bad RAM, bad cpu, bios misconfiguration
    • BIOS time and settings
      • Maintained with the motherboard battery
    • Boots in incorrect order
      • Check boot order in BIOS
      • Does the selected device have a valid OS?
      • Is the device connected?
  • Crash Screen
    • Blue Screen of Death (BSOD)
      • Windows
      • Driver issue
      • Use last known good configuration
      • Use safe mode
    • Spinning ball of death (SBOD)
      • Mac
      • App bug, bad hardware, disk issue
      • Restart
      • Check logs
    • Black Screen
      • Is the monitor plugged in and turned on?
      • Is the monitor using the correct input?
      • Try another monitor
      • If no video after windows loads, try vga mode (f8)
    • No power
      • Use a multimeter to check for power
      • Is anything powered on? Fans?
        • Check PSU output
        • On a laptop, check the power brick
        • On a desktop, check the power switch
        • If the laptop is plugged in and working but shuts off when unplugged, the battery is bad or not plugged into board
    • Sluggish performance
      • Task manager, update, disk space, powersaving, virus
    • Overheating
      • Check fans, vents, heat sink, bad components
      • Use a can of compressed air to clean out dust
      • cpuid.com
    • Intermittent Shutdown
      • Heat, Hardware
      • Eliminate working parts
    • App crashes
      • Look for error message, check event logs, check the reliabiltiy monitor
    • Grinding noises
      • Bad hard drive, bad fan, blown capacitor, bad power supply
    • Lockups
      • Check for responses, try shortcuts, update drivers and software, low resources
    • Continuous Reboot
      • F8

Storage Troubleshooting

  • Symptoms
    • R/W errors
    • Slow performance
    • Clicking/Grinding noises
  • Disk Failures
    • Backups, Check for loose/damaged cables
    • Check for overheating, power supply, run hardware diagnostics
  • RAID Failures
    • RAID not found
      • Faulty controller
    • RAID stops working
      • Check the console, every RAID is different
    • RAID failure conditions
      • RAID 0: 1 drive failure
      • RAID 1: 1 must remain operational
      • RAID 5: All drives must remain operational but one
      • RAID 10: All but one from each set of mirrors

Video Troubleshooting

  • Native Resolution
    • Check the monitor manual
  • Burn-in
    • Static images on the screen
    • Use a white page for a while
  • Dead Pixels
    • Pixel is always black
    • Factory defect
  • Flashing Screen
    • Replace cable
    • Check display settings
  • Projector Problems
    • Check the lamp
      • Relatively expensive to replace
      • May be hot
    • Check the filter
    • Check the fan

Mobile Troubleshooting

  • Battery
    • Check battery usage
    • Aging batteries need to be replaced
    • Swollen battery
      • Buildup of gas
      • Fire risk
      • Dispose and replace
  • Liquid Damage
    • LCI
      • Liquid Contact Indicator
    • Power phone down, remove case
    • Place in silica gel
    • Leave it alone for at least a day
    • Power on
  • Digitizer
    • Touch screen not working
    • Check for cracks
    • Reboot

Networking Troubleshooting

  • Is there a link light?
  • Ping loopback
  • Ping gateway
  • Ping local device
  • Ping 8.8.8.8
  • Tracert