CompTIA A+ Core 1 220-1201

CompTIA A+ Core 1 220-1201 Flashcards: 455 cards

455 free CompTIA A+ Core 1 flashcards from the course's cheat sheet and glossary. Tap a card to flip it. Mark the ones you know and they drop out of the deck; the rest keep coming back.

Acronyms 272

12VHPWR: 12 volt high power connector. The 16-pin connector on new graphics cards rated up to 600 W.
3G: Third-generation cellular. The older mobile data generation, being switched off by carriers.
4G: Fourth-generation cellular. The LTE generation of mobile broadband.
5G: Fifth-generation cellular. The current mobile network generation with higher speed and lower latency than LTE.
802.11: IEEE 802.11. The family of Wi-Fi standards.
802.3af: IEEE 802.3af. The original Power over Ethernet standard: about 15.4 W at the switch, 12.95 W at the device.
802.3at: IEEE 802.3at. PoE+: about 30 W at the switch, 25.5 W at the device.
802.3bt: IEEE 802.3bt. PoE++: 60 W (Type 3) or up to 90 W (Type 4) using all four pairs.
AAA: Authentication, authorization, and accounting. Prove who you are, decide what you may do, record what you did.
AAAA: Quad-A record. The DNS record that maps a name to an IPv6 address.
AC: Alternating current. Mains power, which reverses direction 60 times a second in North America.
ACK: Acknowledgment. The TCP flag or message confirming data arrived.
ADF: Automatic document feeder. The tray on a scanner or printer that feeds a stack of pages.
AES: Advanced Encryption Standard. The standard symmetric cipher, with 128, 192, or 256-bit keys.
AHCI: Advanced Host Controller Interface. The SATA controller mode that enables native command queuing and hot plug.
AIO: All-in-one. A liquid CPU cooler with a sealed pump and radiator, or a computer built into its monitor.
AM4: AMD socket AM4. AMD's PGA socket for Ryzen processors through 2022.
AM5: AMD socket AM5. AMD's current LGA socket for Ryzen processors with DDR5.
AMD: Advanced Micro Devices. The other major maker of x86 CPUs and of Radeon graphics.
AMD-V: AMD Virtualization. AMD's hardware support for running virtual machines.
AP: Access point. The radio that bridges Wi-Fi clients onto the wired network.
API: Application programming interface. The defined way one program talks to another, such as the web endpoints a cloud service exposes.
APIPA: Automatic Private IP Addressing. The 169.254.x.x address a host gives itself when it cannot reach a DHCP server.
ARM: Advanced RISC Machine. The low-power processor design in phones, tablets, and newer laptops.
ARP: Address Resolution Protocol. Finds the MAC address that goes with a known IPv4 address on the local segment.
ATX: Advanced Technology Extended. The standard full-size desktop motherboard and power supply form factor, 12 x 9.6 inches.
B+M: B and M keyed M.2 module. An M.2 SSD notched for both B and M key slots, usually a SATA drive.
BIOS: Basic Input/Output System. The original PC firmware: 16-bit, text setup, MBR disks up to 2 TB.
BNC: Bayonet Neill-Concelman connector. The twist-lock coax connector used on older LANs, test equipment, and CCTV.
BSOD: Blue screen of death. The Windows stop error screen from a driver or hardware fault.
BYOD: Bring your own device. Staff use personal phones and laptops for work.
CAS: Column address strobe (latency). The delay in clock cycles before memory returns requested data; lower is faster.
CCFL: Cold cathode fluorescent lamp. The backlight in older LCDs, driven by a high-voltage inverter.
CCTV: Closed-circuit television. Security cameras on a private video system.
CD: Compact disc. Optical media holding about 700 MB.
CEC: Consumer Electronics Control. The HDMI feature that lets one remote control several devices.
CF: CompactFlash card. A larger, older flash memory card used in professional cameras and industrial gear.
CIFS: Common Internet File System. An older name for the SMB file-sharing protocol.
CL16: CAS latency 16. A memory module that answers in 16 clock cycles.
CMOS: Complementary metal-oxide semiconductor. The small battery-backed memory that keeps firmware settings and the clock.
CNAME: Canonical name record. A DNS alias: one name points to another name.
CPU: Central processing unit. The processor that executes instructions.
CR2032: CR2032 coin cell. The 3 V lithium coin battery that keeps CMOS settings and the clock.
CRM: Customer relationship management. Software for tracking customers and sales, usually SaaS.
CRT: Cathode ray tube. The old glass-tube monitor; holds dangerous voltage even when unplugged.
CSM: Compatibility Support Module. UEFI's legacy mode that boots BIOS-style operating systems.
DaaS: Desktop as a service. VDI hosted by a cloud provider.
DB9: D-subminiature 9-pin connector. The 9-pin serial port connector.
dBm: Decibels relative to one milliwatt. An absolute power level: 0 dBm is 1 mW; Wi-Fi signals are negative numbers such as -65 dBm.
DC: Direct current. Current in one direction: batteries, power supply outputs, and PoE.
DCI-P3: Digital Cinema Initiatives P3 color space. A wide color gamut used for video and film work.
DDR: Double data rate (memory). The family of SDRAM generations (DDR3, DDR4, DDR5) that transfer twice per clock cycle.
DDR3: Double data rate 3 SDRAM. The memory generation before DDR4, 240-pin DIMMs at 1.5 V.
DDR4: Double data rate 4 SDRAM. The common memory generation: 288-pin DIMM, 260-pin SODIMM, 1.2 V, 2133 to 3200 MT/s.
DDR4-2666: DDR4 at 2666 megatransfers per second. A slower DDR4 speed rating.
DDR4-3200: DDR4 at 3200 megatransfers per second. A DDR4 module speed rating.
DDR5: Double data rate 5 SDRAM. The current memory generation: higher speed, 1.1 V, on-module voltage regulation.
DE-15: D-subminiature E shell, 15 pins. The formal name of the VGA connector.
DFS: Dynamic frequency selection. Wi-Fi channels in the 5 GHz band that must yield to radar.
DHCP: Dynamic Host Configuration Protocol. Hands out IP addresses, masks, gateways, and DNS servers automatically (UDP 67 and 68).
DIMM: Dual in-line memory module. The full-size desktop memory stick.
DKIM: DomainKeys Identified Mail. Outgoing mail is digitally signed; the public key is published in DNS.
DMARC: Domain-based Message Authentication, Reporting, and Conformance. A DNS policy telling receivers what to do with mail that fails SPF or DKIM, and where to send reports.
DNS: Domain Name System. Translates names such as www.example.com into IP addresses (UDP 53, TCP 53 for zone transfers).
DOCSIS: Data Over Cable Service Interface Specification. The standard cable modems use to carry internet over the TV coax.
DORA: Discover, Offer, Request, Acknowledge. The four-step DHCP lease exchange.
DP: DisplayPort. The computer-oriented digital video connector with daisy-chaining and high bandwidth.
DRAM: Dynamic random-access memory. The main system memory technology, refreshed constantly.
DSL: Digital subscriber line. Internet over the telephone line through an RJ11 jack; speed falls with distance from the exchange.
DSSS: Direct-sequence spread spectrum. The spreading technique used by early 2.4 GHz Wi-Fi (802.11b).
DVD: Digital versatile disc. Optical media holding 4.7 GB, or 8.5 GB dual layer.
DVI: Digital Visual Interface. The older white digital video connector; DVI-D digital, DVI-A analog, DVI-I both.
DVI-A: DVI analog. A DVI connector that carries only an analog VGA-style signal.
DVI-D: DVI digital. A DVI connector that carries only a digital signal.
DVI-I: DVI integrated. A DVI connector carrying both digital and analog signals.
ECC: Error-correcting code memory. Memory that detects and fixes single-bit errors; used in servers and workstations.
EPS: Entry-level Power Supply specification (CPU power connector). The 4-pin or 8-pin 12 V connector near the CPU socket.
eSATA: External SATA. A SATA port on the outside of the case for external drives.
ESD: Electrostatic discharge. Static electricity that can destroy chips; prevented with a wrist strap, mat, and antistatic bags.
eSIM: Embedded SIM. A SIM built into the phone and provisioned by software.
FDM: Fused deposition modeling. 3D printing that melts plastic filament through a nozzle layer by layer.
FTP: File Transfer Protocol. Plaintext file transfer on TCP 21 (control) and 20 (data); replace with SFTP or FTPS.
FTPS: FTP Secure. FTP wrapped in TLS, ports 990 and 989 (implicit) or 21 with an upgrade (explicit).
GB: Gigabyte. About a billion bytes; the unit for RAM, storage, and data caps.
GG45: GG45 connector. A backward-compatible Cat 7 and Cat 8 connector that also accepts RJ45 plugs.
GHz: Gigahertz. Billions of cycles per second; CPU clock speed and Wi-Fi band frequency.
GPS: Global Positioning System. Satellite positioning, also used as a stratum 0 time reference.
GPT: GUID Partition Table. The modern disk partition scheme: any disk size, up to 128 partitions, required for UEFI boot.
GPU: Graphics processing unit. The processor that renders images; on a card or built into the CPU.
HD: High definition. Video resolutions of 1280 x 720 (HD) and 1920 x 1080 (Full HD).
HDD: Hard disk drive. Spinning magnetic storage: cheap per terabyte, slower, and fragile.
HDMI: High-Definition Multimedia Interface. The common digital video and audio connector for monitors and TVs.
HEPA: High-efficiency particulate air (filter). A filter that traps fine dust; used in vacuums safe for electronics and toner.
HR: Human resources. The department that handles staff records; its documents are the exam's example of sensitive printouts.
HSM: Hardware security module. A tamper-resistant appliance or card that generates, stores, and uses cryptographic keys.
HTTP: Hypertext Transfer Protocol. Web traffic in the clear on TCP 80.
HTTPS: Hypertext Transfer Protocol Secure. HTTP inside TLS on TCP 443.
HVAC: Heating, ventilation, and air conditioning. The building's climate systems, which keep server rooms cool and are themselves networked controls.
Hz: Hertz. Cycles per second; display refresh rate, AC mains frequency, and signal frequency.
IaaS: Infrastructure as a service. The provider supplies virtual machines, storage, and networks; you manage the operating system and up.
ID: Identifier or identification. A name or number that uniquely labels a user, device, session, or record.
IDE: Integrated Drive Electronics. The legacy parallel ATA drive interface, and the legacy SATA controller mode.
IDS: Intrusion detection system. Watches a copy of the traffic and alerts on attacks; cannot block them.
IMAP: Internet Message Access Protocol. Reads mail that stays on the server, synced across devices; TCP 143, secure 993.
IOPS: Input/output operations per second. A measure of how many small reads and writes a drive handles per second.
IoT: Internet of Things. Networked devices such as cameras, sensors, thermostats, and smart TVs.
IP: Internet Protocol. The Layer 3 protocol that addresses and routes packets between networks.
IPS: In-plane switching. The LCD panel type with the best color accuracy and viewing angles. Also: Intrusion prevention system. A security device that sits inline and blocks attacks as they pass, unlike an IDS that only alerts.
IPv4: Internet Protocol version 4. 32-bit addresses written as four decimal octets, such as 192.168.1.10.
IPv6: Internet Protocol version 6. 128-bit addresses in eight hex groups; no broadcast, built-in autoconfiguration.
iSCSI: Internet SCSI. SCSI storage commands over a TCP/IP network, giving block-level storage without Fibre Channel.
ISO: International Organization for Standardization; also an ISO disc image. The standards body, and the .iso file format that holds a complete disc image.
ISP: Internet service provider. The company that connects you to the internet.
IT: Information technology. Computers, networks, and the people who run them.
ITX: Information Technology eXtended (Mini-ITX). The 6.7-inch square small-form-factor motherboard size.
LAN: Local area network. One site's network: a building, floor, or campus that one organization owns and runs.
LC: Lucent connector. The small square snap-in fiber connector, the most common on modern transceivers.
LCD: Liquid crystal display. The flat panel that shapes light from a backlight into an image; TN, IPS, and VA are the panel types.
LDAP: Lightweight Directory Access Protocol. Queries a directory such as Active Directory for users and groups; TCP 389, secure 636.
LDAPS: LDAP Secure. LDAP over TLS on TCP 636.
LED: Light-emitting diode. A small light source: the status lights on a port, the lamp in cheap fiber transmitters, and modern display backlights.
LGA: Land grid array. A CPU socket where the pins are in the socket and the chip has flat contacts (Intel, and AMD AM5).
LTE: Long-Term Evolution. 4G cellular data; the workhorse mobile broadband standard.
M.2: M.2 form factor. The small card slot for SSDs and wireless cards, keyed B, M, or B+M.
MAC: Media access control (address). The 48-bit hardware address burned into a network interface, used at Layer 2.
macOS: Mac operating system. Apple's desktop operating system.
MAN: Metropolitan area network. A city-sized network: bigger than a LAN, smaller than a WAN.
MB: Megabyte. About a million bytes; file sizes and older media capacities.
MBR: Master boot record. The legacy partition scheme: disks up to 2 TB, four primary partitions, BIOS boot.
MDIX: Medium-dependent interface crossover. Auto-MDIX ports sense the cable and swap transmit and receive pairs, so crossover cables are rarely needed.
MDM: Mobile device management. Software that enrolls phones and tablets and enforces policy: passcodes, encryption, apps, remote wipe.
MHz: Megahertz. Millions of cycles per second; memory speed, radio channels, and older CPU clocks.
microSD: Micro Secure Digital card. The fingernail-sized flash card in phones, cameras, and single-board computers.
MIMO: Multiple input, multiple output. Using several antennas at once to send parallel data streams for more speed.
ms: Millisecond. One thousandth of a second; latency and response times.
mSATA: Mini-SATA. A small SATA SSD card used in older laptops before M.2.
MT/s: Megatransfers per second. The speed rating of memory: millions of data transfers per second.
MU-MIMO: Multi-user MIMO. The access point serves several clients at the same time with separate streams.
MX: Mail exchanger record. The DNS record that says which server accepts email for a domain.
NAS: Network-attached storage. A file server appliance that shares folders over the regular network using SMB or NFS.
NAT: Network address translation. Rewrites private inside addresses to a public address at the router so many hosts can share it.
NAT64: Network address translation 6 to 4. Lets IPv6-only hosts reach IPv4-only servers by translating between the two.
NFC: Near-field communication. Very short range radio (about 4 cm) at 13.56 MHz for tap-to-pay and badge readers.
NFS: Network File System. The Unix and Linux file-sharing protocol.
NIC: Network interface card. The adapter that connects a computer to the network, wired or wireless.
NS: Name server record. The DNS record listing the authoritative name servers for a zone.
NTP: Network Time Protocol. Synchronizes clocks across the network (UDP 123); wrong time breaks Kerberos, certificates, and logs.
NVMe: Non-Volatile Memory Express. The fast SSD interface that talks to PCIe lanes directly, usually in an M.2 slot.
OFDMA: Orthogonal frequency-division multiple access. Wi-Fi 6 splits a channel into small sub-channels so many clients share it efficiently.
OLED: Organic light-emitting diode. A display whose pixels emit their own light: perfect blacks, thin, but prone to burn-in.
OM3: Optical multimode 3. Laser-optimized 50 micron multimode fiber, aqua, 10 Gbps to about 300 m.
ONT: Optical network terminal. The box that converts the fiber provider's light signal to Ethernet at the customer premises.
OS: Operating system. The software that manages hardware and runs applications: Windows, macOS, Linux, iOS, Android.
OSI: Open Systems Interconnection model. The seven-layer reference model used to describe where a protocol or device does its work.
PaaS: Platform as a service. The provider runs the platform (OS, runtime, database); you deploy code.
PAN: Personal area network. A network within arm's reach, such as Bluetooth between a phone and earbuds.
PC: Personal computer. A desktop or laptop for one user.
PC4-25600: PC4-25600 bandwidth label. The DDR4-3200 speed written as 25,600 MB/s of bandwidth.
PCI: Peripheral Component Interconnect. The older expansion bus; PCIe (PCI Express) is its modern serial successor.
PCL: Printer Command Language. HP's page description language, fast and common in office printing.
PDF: Portable Document Format. Adobe's fixed-layout document file.
PGA: Pin grid array. A CPU package with pins on the chip that drop into holes in the socket (AMD AM4).
PIN: Personal identification number. A short numeric secret, a something-you-know factor.
PJL: Printer Job Language. Commands that wrap a print job to set options and switch languages.
PoE: Power over Ethernet. Delivers DC power to devices over the data cable: 802.3af 15.4 W, 802.3at 30 W, 802.3bt 60 to 90 W.
POP3: Post Office Protocol version 3. Downloads mail to one device and usually deletes it from the server; TCP 110, secure 995.
POST: Power-on self-test. The firmware's hardware check at power-up; failures show as beep codes or a POST card reading.
PPI: Pixels per inch. Pixel density; higher is sharper.
PRL: Preferred roaming list. The carrier's list of networks a phone may use, updated over the air.
PS: PostScript. Adobe's page description language, favored for graphics and publishing.
PSU: Power supply unit. Converts wall AC to the DC voltages a computer needs: 12 V, 5 V, 3.3 V.
PTR: Pointer record. The reverse DNS record: IP address back to a name.
PVC: Polyvinyl chloride. The ordinary cable jacket, which gives off toxic smoke; plenum cable is required in air spaces.
PWM: Pulse-width modulation. Controls fan speed (4-pin headers) and LED brightness by switching power on and off rapidly.
PXE: Preboot Execution Environment. Booting a computer from the network to install or image an operating system.
QHD: Quad high definition. 2560 x 1440 resolution.
QR: Quick response code. The square barcode a phone camera reads.
RADIUS: Remote Authentication Dial-In User Service. The AAA server behind Wi-Fi Enterprise, VPNs, and 802.1X; UDP 1812 and 1813.
RAID: Redundant array of independent disks. Combining disks for speed, capacity, or fault tolerance: 0 stripe, 1 mirror, 5 stripe with parity, 6 double parity, 10 mirrored stripes.
RAM: Random-access memory. The working memory that holds running programs and data; lost at power off.
RDP: Remote Desktop Protocol. Microsoft's remote graphical desktop on TCP 3389.
RFID: Radio-frequency identification. Tags read by radio for badges, inventory, and asset tracking.
RG-59: Radio Guide 59 coaxial cable. Thinner coax for short runs such as CCTV, often with a BNC connector.
RG-6: Radio Guide 6 coaxial cable. The modern coax grade for cable TV and cable modems, with an F-type connector.
RGB: Red, green, blue. The three color channels of displays and the name of decorative lighting headers.
RISC: Reduced instruction set computer. A processor design with a small set of simple instructions, as in ARM.
RJ11: Registered jack 11. The small telephone plug, used for analog phone lines and DSL.
RJ45: Registered jack 45. The eight-pin plug on Ethernet twisted-pair cables (properly an 8P8C connector).
ROM: Read-only memory. Non-volatile memory holding firmware.
RPM: Revolutions per minute. Rotation speed: hard drive platters at 5400 or 7200, and fans.
RS-232: Recommended Standard 232 serial. The classic serial port: slow, simple, and still used for console access and legacy devices.
RX: Receive. The receiving side of a link or the receiving fiber strand.
S.M.A.R.T: Self-Monitoring, Analysis, and Reporting Technology. Drive self-diagnostics that warn of impending failure.
SaaS: Software as a service. Complete applications delivered over the web, such as email and office suites.
SAN: Storage area network. A dedicated network that gives servers block-level access to shared disk arrays.
SAS: Serial Attached SCSI. The enterprise drive interface for servers; faster, dual-ported, and accepts SATA drives.
SATA: Serial ATA. The standard drive interface: SATA III at 6 Gb/s, 7-pin data and 15-pin power cables.
SC: Subscriber connector. The larger square push-pull fiber connector, common on older gear and patch panels.
SCADA: Supervisory control and data acquisition. Systems that monitor and control industrial processes such as power, water, and manufacturing.
SCP: Secure Copy Protocol. Simple file copying over SSH, TCP 22.
SCSI: Small Computer System Interface. The old parallel drive and peripheral bus; SAS and iSCSI carry its command set today.
SD: Secure Digital card. The flash memory card used in cameras and devices; miniSD and microSD are the smaller sizes.
SFP: Small form-factor pluggable transceiver. The hot-swappable module that gives a switch port its fiber or copper interface, 1 Gbps.
SFTP: SSH File Transfer Protocol. File transfer inside an SSH session, TCP 22.
SFX: Small form factor power supply. A compact power supply for small cases.
SIM: Subscriber identity module. The card or embedded chip that identifies a phone to the cellular network.
SLA: Service level agreement. The contract stating measurable service commitments, such as 99.9% uptime.
SLAAC: Stateless address autoconfiguration. IPv6 hosts build their own address from the router's advertised prefix, no DHCP server needed.
SMB: Server Message Block. Windows file and printer sharing on TCP 445.
SMT: Simultaneous multithreading. One physical core runs two threads at once (Intel calls it Hyper-Threading).
SMTP: Simple Mail Transfer Protocol. Sends email between servers on TCP 25; clients submit on 587 with TLS.
SNMP: Simple Network Management Protocol. Polls and receives alerts from network devices (UDP 161 polls, 162 traps).
SODIMM: Small outline DIMM. The short memory module used in laptops and small PCs.
SOHO: Small office, home office. A small network with a consumer-grade router doing NAT, DHCP, Wi-Fi, and firewall in one box.
SPAN: Switched port analyzer. A switch feature that mirrors traffic from ports or VLANs to a monitoring port.
SPF: Sender Policy Framework. A DNS TXT record listing which servers may send mail for a domain.
SQL: Structured Query Language. The language used to query databases; also the name of the servers on TCP 1433 (Microsoft) and 3306 (MySQL).
SRAM: Static random-access memory. Faster memory that needs no refresh, used for CPU cache.
SSD: Solid-state drive. Flash storage with no moving parts: fast, silent, and shock resistant.
SSH: Secure Shell. Encrypted remote command-line access and file transfer on TCP 22; replaces Telnet and FTP.
SSID: Service set identifier. The Wi-Fi network name that access points broadcast and clients join.
ST: Straight tip connector. The round bayonet twist-lock fiber connector; legacy.
STP: Shielded twisted pair. Twisted-pair cable with foil or braid around the pairs for noisy environments; the shield must be grounded.
SYN: Synchronize flag. The first packet of a TCP handshake.
Syslog: System logging protocol. Sends device log messages to a central server on UDP 514 with severity levels 0 to 7.
T568A: TIA/EIA 568A wiring standard. One of the two pin-outs for RJ45 cables; green pair on pins 1 and 2.
T568B: TIA/EIA 568B wiring standard. The more common RJ45 pin-out; orange pair on pins 1 and 2.
TACACS+: Terminal Access Controller Access-Control System Plus. Cisco's AAA protocol for device administration on TCP 49; encrypts the whole payload and separates authentication from authorization.
TB: Terabyte. About a trillion bytes; the unit for large drives.
TCP: Transmission Control Protocol. Reliable, ordered, connection-based transport: three-way handshake, acknowledgments, retransmission.
TFTP: Trivial File Transfer Protocol. Bare-bones UDP 69 file transfer with no login, used for firmware and config files.
TFX: Thin form factor power supply. A slim power supply for low-profile desktop cases.
TLD: Top-level domain. The last part of a domain name, such as .com or .org.
TLS: Transport Layer Security. The encryption layer under HTTPS and most secure protocols; use 1.2 or 1.3.
TN: Twisted nematic. The fastest and cheapest LCD panel type, with poor viewing angles and color.
TPM: Trusted Platform Module. A security chip on the motherboard that stores keys and measurements; required for BitLocker and Windows 11.
TRIM: TRIM command. Tells an SSD which blocks are no longer in use so it can erase them ahead of time.
TTL: Time to live. A counter that keeps packets and DNS records from living forever.
TV: Television. A display or broadcast receiver; smart TVs are IoT devices.
TX: Transmit. The sending side of a link or the sending fiber strand.
TXT: Text record. A free-text DNS record, used for SPF, DKIM, DMARC, and domain ownership checks.
UDP: User Datagram Protocol. Connectionless, fast transport with no delivery guarantee; used for voice, video, DNS, DHCP.
UEFI: Unified Extensible Firmware Interface. Modern firmware that replaces BIOS: GPT disks, Secure Boot, mouse-driven setup.
UHD: Ultra high definition. 3840 x 2160 resolution, commonly called 4K.
UPS: Uninterruptible power supply. A battery unit that keeps equipment running through a power cut and conditions the power.
US: United States. The country; US standards, 60 Hz mains, and US connector conventions.
USB: Universal Serial Bus. The standard port for peripherals, storage, and charging.
USB-A: USB Type-A connector. The classic flat rectangular USB plug.
USB-C: USB Type-C connector. The small reversible connector that carries USB, DisplayPort, Thunderbolt, and power delivery.
USB4: Universal Serial Bus 4. The 40 Gbps USB generation over USB-C, based on Thunderbolt.
UTM: Unified threat management. One appliance bundling firewall, IDS/IPS, antivirus, content filtering, and VPN.
UTP: Unshielded twisted pair. The standard copper network cable: four twisted pairs, no shield.
VA: Vertical alignment. An LCD panel type with high contrast and deep blacks, slower than IPS.
VAC: Volts AC. An alternating-current voltage rating, such as 120 VAC.
VCSEL: Vertical-cavity surface-emitting laser. The cheap laser used in multimode fiber transceivers.
VDI: Virtual desktop infrastructure. User desktops run as virtual machines in the data center; the user connects with a thin client.
VGA: Video Graphics Array. The blue 15-pin analog video connector.
VLAN: Virtual local area network. A logical LAN on a switch: ports in different VLANs are separate broadcast domains.
VM: Virtual machine. A complete computer running as software on a hypervisor.
VNC: Virtual Network Computing. A cross-platform remote desktop protocol.
VoIP: Voice over IP. Telephone calls carried as packets on the data network.
VPN: Virtual private network. An encrypted tunnel across an untrusted network such as the internet.
VRAM: Video RAM. The memory on a graphics card that holds frames and textures.
VT: Virtualization technology. Intel's hardware virtualization support, enabled in firmware.
WAN: Wide area network. Connects LANs across cities or countries, usually over links leased from a provider.
Wi-Fi: Wireless fidelity. The trade name for IEEE 802.11 wireless networking.
WISP: Wireless internet service provider. An ISP that delivers internet by fixed wireless from a tower to an antenna on the building.
WLAN: Wireless local area network. A LAN delivered over Wi-Fi instead of cables.
WPA2: Wi-Fi Protected Access 2. Wi-Fi security using AES with CCMP; still common and acceptable.
WPA3: Wi-Fi Protected Access 3. The current Wi-Fi security standard: SAE in Personal mode, stronger encryption, protected management frames.
WPS: Wi-Fi Protected Setup. The push-button or PIN method for joining Wi-Fi; its PIN mode is insecure and should be disabled.
ZIF: Zero insertion force. A socket or connector that clamps without pushing, used for CPUs and laptop ribbon cables.

The exam itself 8

Exam: CompTIA A+ Core 1, 220-1201 (A+ needs Core 1 and Core 2, 220-1202)
Questions and time: Up to 90 questions in 90 minutes; multiple choice plus performance-based items
Passing: 675 on a scale of 100 to 900 (Core 2 needs 700)
Hardware and Network Troubleshooting: 28%
Hardware: 25%
Networking: 23%
Mobile Devices: 13%
Virtualization and Cloud Computing: 11%

Network hardware and services 15

DNS: Names to addresses
DHCP: Addresses, masks, gateways, DNS servers by lease
File share and print server: Shared folders (SMB) and shared printers with queues
Mail server: SMTP out, IMAP or POP3 in
Syslog: Collects logs from devices
Web server: HTTP and HTTPS
AAA: Authentication, authorization, accounting (RADIUS, TACACS+)
Database server: SQL data for applications
NTP: Time
Spam gateway: Filters inbound mail before the mail server
UTM: Unified threat management: firewall, IDS/IPS, antivirus, content filter in one box
Load balancer: Spreads requests across several servers; high availability
Proxy server: Fetches web content on behalf of clients; caching, filtering, logging
SCADA and legacy embedded: Industrial control; old, fragile, isolate on their own network
IoT: Smart devices: thermostats, cameras, speakers, locks; segregate and patch

IP addressing and configuration 17

IPv4 address: 32 bits, four octets 0 to 255, such as 192.168.1.20
Private ranges: 10.0.0.0 to 10.255.255.255 (/8); 172.16.0.0 to 172.31.255.255 (/12); 192.168.0.0 to 192.168.255.255 (/16)
Public addresses: Everything else; routable on the internet; shared through NAT at the router
APIPA: 169.254.x.x: the client got no DHCP answer; link or DHCP server problem
Loopback: 127.0.0.1 (IPv6 ::1): tests the local TCP/IP stack
Subnet mask: 255.255.255.0 = /24 (254 hosts); 255.255.0.0 = /16; 255.0.0.0 = /8; same network portion means direct delivery, otherwise via the gateway
Default gateway: The router's address on the local network; must be in the same subnet as the host
Static versus dynamic: Static typed in (servers, printers); dynamic from DHCP (workstations, phones); reservations give a fixed address by MAC
IPv6 address: 128 bits, eight hex groups; :: compresses zeros; fe80:: link-local on every interface; 2000::/3 global; no NAT needed
A: Name to IPv4 address
AAAA: Name to IPv6 address
CNAME: Alias of another name
MX: Mail server for a domain
TXT: Free text; carries SPF, DKIM, and DMARC
SPF (TXT): Which servers may send mail for the domain
DKIM (TXT): Cryptographic signature proving the message was not altered and came from the domain
DMARC (TXT): Policy telling receivers what to do when SPF or DKIM fails (none, quarantine, reject) and where to send reports

Internet connection and network types 6

PAN: Personal: Bluetooth, a few meters
LAN: One building or site
WLAN: A LAN over Wi-Fi
MAN: A city or campus
WAN: Between sites, across regions; the internet
SAN: Storage area network: block storage over a dedicated network (Fibre Channel, iSCSI)

Displays 7

LCD TN (twisted nematic): Cheapest, fastest response, poor viewing angles and color
LCD IPS (in-plane switching): Best color and viewing angles; slower and pricier; professional and most laptops
LCD VA (vertical alignment): High contrast, deep blacks; middle on angles and speed
OLED: Each pixel emits its own light; perfect blacks, thin, flexible; risk of burn-in; used in phones and premium laptops
Mini-LED: An LCD with thousands of tiny backlight zones; high brightness and contrast without burn-in
Inverter: Converts DC to AC for CCFL backlights in old LCDs; a dim screen visible with a flashlight means backlight or inverter
Touch screen and digitizer: The digitizer layer senses touch or pen; a cracked digitizer works badly even if the image is fine

Memory, storage, and RAID 7

HDD: Spinning platters; 5,400, 7,200, 10,000, 15,000 rpm; 2.5-inch (laptop) and 3.5-inch (desktop); slow, cheap per TB; fails with clicking and grinding
SSD SATA: No moving parts; about 550 MB/s limited by SATA III; 2.5-inch or mSATA or M.2 SATA
SSD NVMe: Talks PCIe directly; M.2 or add-in card; thousands of MB/s (Gen 3 about 3.5 GB/s, Gen 4 about 7 GB/s)
M.2: A slot and form factor, not an interface: keys B, M, or B+M; sizes 2242, 2260, 2280 (22 mm wide, length in mm); can be SATA or NVMe
SAS: Serial Attached SCSI; enterprise drives, 12 Gb/s, dual ports; SAS controllers accept SATA drives, not the reverse
Removable: USB flash drives; SD, microSD, CompactFlash memory cards; speed classes on the card
Optical: CD 700 MB; DVD 4.7 GB (8.5 dual layer); Blu-ray 25 GB (50 dual layer)

Motherboards, CPUs, firmware, and power 25

PCIe: Lanes x1, x4, x8, x16; a card fits in a longer slot; per lane about 1 GB/s (Gen 3), 2 GB/s (Gen 4), 4 GB/s (Gen 5) each direction; graphics cards use x16
PCI: Legacy 32-bit parallel slot; 133 MB/s shared
Main power: 24-pin (20+4) ATX; 4- or 8-pin EPS for the CPU; 6-pin (75 W) and 8-pin (150 W) PCIe for graphics; 12VHPWR 16-pin up to 600 W
Drive power: SATA 15-pin; Molex 4-pin
SATA and eSATA: 7-pin data ports on the board; eSATA on the rear panel
Headers: Front panel (power, reset, LEDs), USB 2.0 and 3.0, audio, fan (3-pin voltage, 4-pin PWM), RGB
M.2: Key and length printed by the slot; some slots are SATA only, some NVMe only, some both
CPU sockets: Intel LGA (pins in the socket, such as LGA 1700 and 1851); AMD AM4 PGA (pins on the chip) and AM5 LGA; board chipset must match the CPU generation; servers may be multisocket
UEFI versus legacy BIOS: UEFI: GPT disks over 2 TB, Secure Boot, graphical setup, network boot; legacy uses MBR
Boot options: Order of devices; USB or network boot for installs; disable unused to harden
USB permissions: Disable ports or block storage devices to prevent data theft
TPM: Trusted Platform Module: stores keys for BitLocker and Windows Hello; TPM 2.0 required by Windows 11; can be firmware (fTPM) or a chip
Secure Boot: Only signed boot loaders run; blocks boot-sector malware; may need disabling for some Linux or older media
Passwords: Supervisor (setup) versus user (boot) password; cleared by the CMOS jumper or battery removal
Fans and temperature: Fan curves, temperature monitoring, thermal shutdown thresholds
Virtualization support: Intel VT-x or AMD-V must be enabled for hypervisors
HSM: Hardware security module: a dedicated external device for key storage and crypto in servers and enterprises
CMOS battery: CR2032 coin cell; a dead one resets time, date, and settings at every boot
Input: 110 to 120 VAC (North America, 60 Hz) or 220 to 240 VAC (much of the world, 50 Hz); auto-switching or a red voltage selector; wrong setting destroys the supply
Output rails: 3.3 V (orange), 5 V (red), 12 V (yellow), ground (black); 12 V feeds CPU, GPU, and drives
Connectors: 24-pin (20+4) main, EPS CPU, PCIe, SATA power, Molex
Wattage: Add the components' draw and leave headroom; a GPU may need 300 W or more by itself
Efficiency: 80 Plus Bronze, Silver, Gold, Platinum, Titanium; higher wastes less as heat
Modular: Only the cables you need; better airflow
Redundant: Two supplies in servers; one fails, the other carries the load; hot swappable

Printers 7

1 Processing: The page is rasterized into a bitmap in the printer's memory
2 Charging: The primary charge roller (or corona wire) puts a uniform negative charge (about minus 600 V) on the drum
3 Exposing: The laser writes the image, removing charge where toner should stick
4 Developing: Negatively charged toner from the developer roller clings to the exposed areas
5 Transferring: The transfer roller (or corona) gives the paper a positive charge that pulls toner off the drum
6 Fusing: Heat (about 180 C) and pressure melt the toner into the paper; the fuser is hot
7 Cleaning: A blade scrapes leftover toner off the drum; a lamp erases the charge

Mobile devices 7

Battery: Lithium-ion; internal on most modern laptops; discharge and disconnect before other work; swollen means replace now
Keyboard and keys: Ribbon cable under the palm rest; individual keycaps on scissor or butterfly mechanisms
RAM: SODIMM; many thin laptops solder it (not upgradable)
Storage: 2.5-inch SATA or M.2 (SATA or NVMe); check the key and length
Wireless card: M.2 (2230) card; the two antenna leads (main and aux) route through the hinge to the lid; black and white or gray leads must go to their marked terminals
Camera and microphone: In the lid bezel; cable through the hinge; a physical privacy shutter on some
Biometrics and NFC: Fingerprint reader in the power button or palm rest; smart card or NFC reader for badges

Virtualization and cloud 15

Type 1 hypervisor: Bare metal, runs directly on hardware (server virtualization); best performance
Type 2 hypervisor: Runs as an application on a host OS (desktop virtualization, testing)
Sandbox: An isolated VM to open suspicious files or test changes safely
Test and development: Many OS versions on one machine; snapshots to roll back
Application virtualization: Run legacy software or another OS's programs; cross-platform virtualization
VDI: Virtual desktop infrastructure: desktops run on servers, users connect with thin clients
Containers: Share the host kernel; lighter than VMs; package an application with its dependencies
VM requirements: CPU virtualization enabled, enough RAM and storage for each guest, network mode (bridged, NAT, host-only), and security (patch guests, isolate, guard against VM escape)
Public: Provider's shared infrastructure, pay as you go
Private: Dedicated to one organization, on premises or hosted
Hybrid: Private plus public, workloads move between them
Community: Shared by organizations with common needs (government, healthcare)
IaaS: Rent virtual machines, storage, and networks; you manage the OS up
PaaS: A platform to build and run applications; the provider manages OS and runtime
SaaS: A finished application over the web; email, office suites, CRM

Troubleshooting 57

No power, no fans: Outlet, cord, PSU switch and voltage selector, PSU (test with a tester or paperclip), front panel header
Fans spin, no POST, beeps: Beep codes point to RAM or video; reseat RAM and card; one module at a time
Blank screen after POST: Monitor input, cable, GPU seating and power; onboard video
Random shutdown, overheating, burning smell: Dust, failed fan, dried thermal paste, failing PSU; check temperatures in firmware
Proprietary crash screen (BSOD, pinwheel): Driver, RAM (run a memory test), storage, overheating; note the stop code
Sluggish performance, application crashes: RAM shortage, thermal throttling, failing drive, malware
Unusual noise: Fan bearing (whine), HDD (clicking, grinding), coil whine under load
Capacitor swelling or leaking: Board or PSU failure; replace
Inaccurate date and time: CMOS battery (CR2032)
Clicking, grinding: HDD mechanical failure; back up immediately, replace
Bootable device not found: Boot order, loose cable, dead drive, corrupted boot record, USB stick left in
S.M.A.R.T. failure warning: Drive predicts its own failure; back up and replace
Extended read and write times, low IOPS: Failing drive, fragmentation on HDD, nearly full SSD, wrong SATA mode
Data loss or corruption: Failing drive, bad cable, power loss during writes; run chkdsk after a backup
RAID failure, array missing, audible alarm: A failed member; replace the drive and rebuild; check the controller and its battery; a missing array may be a controller or driver
Missing drives in the OS: Not initialized or partitioned, driver, cable, power, disabled port in firmware
LED status indicators: Amber or red on a drive bay means degraded or failed
No image, incorrect input source: Select the right input; check the cable and adapter; try another cable
Dim image: Brightness, power saving, failing backlight or inverter; shine a flashlight at the screen
Fuzzy image, sizing issues: Non-native resolution, scaling, VGA over a long cable, projector focus
Flashing or flickering screen: Loose cable, refresh rate, driver, failing panel or inverter
Incorrect color, distorted image: Bent VGA pins, cable, driver, color profile, degaussing on CRTs
Dead pixels: Panel defect; warranty policy; stuck pixels may recover
Burn-in: Static image on OLED or plasma; pixel shift and screensavers prevent it
Burnt-out bulb, intermittent projector shutdown: Replace the lamp (hours counter); overheating from a clogged filter
Audio issues over HDMI or DisplayPort: Select the display as the output device; cable supports audio
Poor battery health, short life: Aged battery (check health percentage), background apps, brightness, radios; replace
Swollen battery: Stop using it; do not puncture; replace and dispose properly
Improper charging: Cable, adapter wattage, dirty or damaged port, wrong charger
Overheating: Charging while gaming, direct sun, malware, a failing battery
Liquid damage: Power off, do not charge, dry thoroughly; indicators inside show exposure
Digitizer issues, cursor drift, touch calibration: Cracked digitizer, screen protector, calibration utility, moisture
Poor or no connectivity: Airplane mode, Wi-Fi or cellular toggles, SIM seating, forget and rejoin the network, carrier settings
Malware, cannot install apps, degraded performance: Unofficial app sources, full storage, OS out of date, factory reset as last resort
Stylus does not work: Battery or pairing on active pens, wrong pen model, digitizer
Broken screen, damaged port: Replace the assembly; ports are soldered on many devices
Intermittent wireless: Weak signal, interference, channel overlap, roaming between APs, driver
Slow speeds: Congestion, wrong cable category, duplex mismatch, bandwidth hogs, a hub
Limited connectivity, APIPA address: No DHCP: link, cable, VLAN, DHCP server
Intermittent internet: ISP, modem, router overheating, DNS; test the modem directly
Jitter, high latency, poor VoIP: Congestion; no QoS; wireless for voice; satellite links
Port flapping: Link going up and down: bad cable or connector, failing NIC, switch port, duplex or speed mismatch
External interference: Microwaves, motors, fluorescent ballasts, neighbors' Wi-Fi; move to 5 GHz or shielded cable
Authentication failures: Wrong password or key, expired certificate, RADIUS server, MAC filtering, time skew
Lines or streaks down the page: Dirty or scratched drum, low toner, dirty print head (inkjet), a scratch on the fuser
Faded prints: Low toner or ink, economy mode, transfer roller worn, humidity
Speckling: Loose toner in the printer; leaking cartridge; clean
Double or echo images (ghosting): Drum not cleaned, worn drum, fuser problem
Toner not fused, smears when touched: Fuser failed or not reaching temperature; wrong paper
Garbled print: Wrong driver or language (PCL versus PostScript), bad cable, corrupted job, low printer memory
Paper jams, multipage misfeed: Worn pickup rollers or separation pad, damp or wrong paper, overfilled tray, debris
Paper not feeding, tray not recognized: Rollers, tray seating, paper guides, tray sensor, firmware
Multiple prints pending, frozen queue: Restart the print spooler service, clear the queue, check the printer status and connectivity
Incorrect page orientation or size: Driver settings, application settings, tray paper size mismatch
Grinding noise: Gears, rollers, drum drive, foreign object; maintenance kit
Finishing issues (staple jams, hole punch): Clear the finisher, refill staples, check the finisher tray sensors
Connectivity issues: IP change on DHCP (use a reservation), Wi-Fi, cable, sleep mode, firewall

Networking and hardware tools 12

Crimper: Attaches RJ45 or RJ11 plugs to cable ends
Cable stripper: Removes the jacket without nicking conductors
Punchdown tool: Seats wires into a 110 or 66 block or a keystone jack and trims them
Cable tester: Checks wire map, opens, shorts, split pairs; certifiers measure to category
Toner probe (tone generator and probe): Finds the far end of a cable in a bundle or closet
Loopback plug: Tests a NIC or switch port by looping transmit to receive
Wi-Fi analyzer: Shows signal strength, channels, and interference; site surveys
Network tap: Copies traffic on a link for a protocol analyzer without disrupting it
Multimeter: Voltage, continuity, resistance; PSU rails and cables
Power supply tester: Checks each PSU rail and the power-good signal
POST card: Reads the firmware's progress codes when a board will not boot
ESD strap and mat: Prevents static damage while handling boards, RAM, and cards

Questions people ask

How many CompTIA A+ Core 1 220-1201 flashcards are there?

455: 272 Acronyms, 8 The exam itself, 15 Network hardware and services, 17 IP addressing and configuration, 6 Internet connection and network types, 7 Displays, 7 Memory, storage, and RAID, 25 Motherboards, CPUs, firmware, and power, 7 Printers, 7 Mobile devices, 15 Virtualization and cloud, 57 Troubleshooting, 12 Networking and hardware tools. They come from the course's cheat sheet and glossary, so what you drill is what the lessons teach.

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No. The cards you mark as known are remembered in this browser only. Sign in to the course for progress that follows you between devices.