A+ 220-1102

• Laptops


  • Smaller, portable versions of desktop PCs
  • Replaceable items such as keyboards and touchpads
  • Fn key for implementing secondary key functions
  • 2.5" or 1.8" hard drives (SSD, HDD, or hybrid)
  • M.2 and Mini PCle cards
  • SODIMM RAM: DDR3 (204-pin), DDR4 (260-pin), DDR5 (262-pin)
• Smartphones and tablets


  • Have ARM-based CPUs
  • Internal flash memory
  • Multitouch displays
  • Li-ion batteries
  • Often IP68-compliant (dust and watertight)
  • Android = USB-C or microUSB; IOS = USB-C or Lightning connector
• GPS and geotracking


  Provide location information about mobile devices
• Mobile device connectivity


  • Cellular WWAN (5G, 4G, LTE, CDMA, GSM)
  • WISP
  • Wi-Fi (WLAN)
• Network types


  • LAN = local area network
  • WAN = wide area network
  • MAN = metropolitan area network
  • PAN = personal area network
  • SAN = storage area network
  • WMN = wireless mesh network
  • WLAN = wireless local area network
• Networking devices

  • Switches connect computers in a LAN
  • Routers connect LANs and LANs to the Internet
  • Firewalls protect individual computers and networks from unwanted intrusion
  • IDS = intrusion detection system
  • IPS = intrusion prevention system
• Networking connectors


  • Twisted pair (RJ45, RJ11)
  • Fiber optic (SC, ST, and LC)
  • Coaxial (RG-6, F-connector)
• Straight through cable


  568B to 568B
• Crossover cable


  568B to 568A
• IPv4 addresses


  • 32-bit dotted-decimal numbers (example: 192.168.1.1)
  • Can be statically (manually) inputted or dynamically (automatically) assigned (DHCP)
• 127.0.0.1


  Loopback address
• APIPA


  169.254.x.x (also known as link-local)
• IPv6 addresses


  • 128-bit hexadecimal numbers (example: 2001:7120:0000:8001:0000:0000:0000:1F10)
  • ::1 is the loopback address
  • Link-local addresses begin with FE80::/10 prefix
• Common network speeds


  • 1000 Mbps (Gigabit Ethernet)
  • 10 Gbps (10 Gbps Ethernet)
• Networking protocols


  • FTP (File Transfer Protocol)
  • Secure versions: FTPS and SFTP
  • SSH (Secure Shell)
  • Telnet
  • SMTP (Simple Mail Transfer Protocol)
  • Secure version uses SSL/TLS
  • DNS (Domain Naming System)
  • DHCP (Dynamic Host Configuration Protocol)
  • HTTP (Hypertext Transfer Protocol)
  • POP3 (Post Office Protocol)
  • Secure version uses SSL/TLS
  • NetBIOS/NetBT (NetBIOS over TCP/IP)
  • IMAP (Internet Message Access Protocol)
  • Secure version uses SSL/TLS
  • SNMP (Simple Network Management Protocol)
  • LDAP (Lightweight Directory Access Protocol)
  • Secure version uses SSL/TLS
  • HTTPS (HTTP Secure)
  • SMB/CIFS (Server Message Block/Common Internet File System)
  • RDP (Remote Desktop Protocol)
• Wireless Ethernet standards


  • 802.11a, 5 GHz
  • 802.11b, 2.4 GHz
  • 802.11g, 2.4 GHz
  • 802.11n, 5 and 2.4 GHz
  • 802.11ac (Wi-Fi 5), 5 GHz
  • 802.11ax (Wi-Fi 6), 5 GHz
• 2.4 GHz wireless channels


  • 1-11
• 5 GHz wireless channels


  • 36, 40, 44, 48, 149, 153, 157, 161, 165
• Bluetooth


  • Short-range technology aimed at simplifying communications and synchronization among network devices
  • Class I maximum transmission range: 100 meters
  • Class || (most common) range: 10 meters
  • Class III range: 1 meter
  • Class 4 range: .5 meter
• NAT (Network Address Translation)

  • Process of modifying an IP address as it crosses a router
  • Translates from one network to another
• Port forwarding


  Forwards an external network port to an internal IP address and port
• Screened subnet (aka DMZ)


  Area of network for servers, not within LAN but between LAN and the Internet
• QoS (quality of service)


  Prioritizes computers or applications
• PoE (Power over Ethernet)

  802.3af PoE devices send Ethernet data and power over twisted pair cable to compliant devices (for example, a PoE injector)
• Video cards


  • Typically connect to motherboards by way of x16 PCle expansion slots
  • Video connector types include DVI, VGA, HDMI, Mini-HDMI, DisplayPort
• USB


  • Type A/Type B connectors are used by desktops/laptops
  • microUSB and USB-C connectors are used by tablets/smartphones, etc.
  • USB 2.0 (high-speed) = 480 Mbps
  • USB 3.0 (SuperSpeed) = 5 Gbps
  • USB 3.1 (SuperSpeed+) = 10 Gbps
  • USB 3.2 = 10/20 Gbps (requires USB-C)
• RAM


  • DIMMs include DDR3 (240 pins), DDR4 (288 pins), and DDR5 (288 pins), none are backward compatible
  • Example of DDR transfer rate: DDR4-2666 = 21,333 MB/s
  • Dual-channel is double width, 128-bit bus
  • Triple-channel is 3x the width, 192-bit bus
  • Quad-channel is 4x the width, 256-bit bus
  • ECC detects and corrects errors
• Storage drives


  • HDD: Hard disk drive (magnetic-based)
  • SSD: Solid-state drive (flash-based). Can be SATA or M.2
  • SATA: Serial ATA uses a 15-pin power connector and 7-pin data connector
  • SATA Rev 3 6 Gb/s, Rev 3.2 (SATA Express) = 16 Gbps
• RAID


  • RAID 0 = striping (not fault tolerant)
  • RAID 1 = mirroring
  • RAID 5 = striping with parity
  • RAID 10 is mirrored sets that are striped
• Power supply connectors


  • ATX 12V 2.x power supplies connect to motherboard (24-pin cable), CPU (4-pin/8-pin), PCle video (6 or 8-pin), SATA (15-pin), Molex (4-pin)
• BIOS/UEFI


  • Identifies, tests, and initializes components and boots to storage drive, optical disc, USB flash drive, or network via PXE
  • CR2032 lithium battery provides backup power
  • Configurations: Time/date, boot device priority (boot order), passwords, power management, WOL, monitoring, clock and bus speeds, virtualization support (Intel VT or AMD-V), enable/disable devices, and intrusion detection
  • For BIOS/UEFI update, flash it with new firmware
• CPU


  • Takes care of most calculations
  • Speed measured in GHz
  • PGA (AMD) = Pin Grid Array
  • LGA (Intel) = Land Grid Array
  • L1/L2 cache in each core
  • L3 cache is shared among entire CPU
  • Thermal paste is required whenever heat sink is installed
  • TDP = thermal design power (example: 140 watts)
• Laser-printing imaging process


  1. Processing

  2. Charging

  3. Exposing

  4. Developing

  5. Transferring

  6. Fusing

  7. Cleaning
• Printer configuration settings


  • Duplexing = printing on both sides
  • Orientation = portrait or landscape
  • Quality = DPI (600 or 1200)
  • Tray settings (such as size = 8.5" x 11")
• Cloud types


  • SaaS (software as a service)
  • laaS (infrastructure as a service)
  • PaaS (platform as a service)
• Cloud concepts


  • Metered utilization (service): only the services accessed are paid for
  • Rapid elasticity: ability to scale the network quickly
• Virtualization


  • Type 1 hypervisor is native or bare metal (has direct access to hardware)
  • Type 2 is hosted; runs on top of OS
  • Examples: VMware, Hyper-V, VirtualBox
  • Network connectivity: bridged (direct access to Internet), NAT (separated access), host-only (private, no Internet), or no networking
• CompTIA 6-step troubleshooting methodology

  1. Identify the problem

  2. Establish a theory of probable cause

  3. Test the theory to determine cause

  4. Establish a plan of action to resolve the problem and implement the solution

  5. Verify full system functionality and, if applicable, implement preventive measures

  6. Document findings, actions, and outcomes
• Time/date resets to earlier date

  Check lithium battery
• Trouble with CPU


  Check CPU fan, heat sink and thermal compound, overclocking setting in BIOS, and whether CPU is secure