A+ acronyms and glossary (Core 1 and Core 2)

Glossary

AAAAuthentication, Authorization, and Accounting

The framework for controlling access: prove who you are (authentication), decide what you may do (authorization), and record what you did (accounting). RADIUS and TACACS+ are classic AAA servers. 220-1201 2.0 (Networking)

AAAAAuthentication, Authorization, Accounting, and Auditing

CompTIA's A+ list expands it as the AAA access framework (authentication, authorization, accounting) plus auditing, the later review of those records. In DNS, however, AAAA is the record that maps a hostname to an IPv6 address, the IPv6 equivalent of an A record. 220-1201 2.0 (Networking)

ACLAccess Control List

An ordered list of rules that permit or deny traffic or access by criteria such as address, port or user. Firewalls and routers check rules top-down, first match wins, with an implicit deny at the end; NTFS permissions are also ACLs. 220-1202 2.0 (Security)

ADFAutomatic Document Feeder

The tray on a scanner or multifunction printer that pulls in a stack of pages one at a time so they can be scanned without lifting the lid for each sheet. Misfeeds and streaks on ADF scans usually point to dirty rollers or glass. 220-1201 3.0 (Hardware)

AESAdvanced Encryption Standard

The symmetric block cipher that encrypts most data today, with 128-, 192- or 256-bit keys. It secures Wi-Fi under WPA2 and WPA3 (replacing the broken RC4 of WEP and TKIP), BitLocker, FileVault and TLS. 220-1202 2.0 (Security)

AMDAdvanced Micro Devices, Inc.

The chipmaker whose Ryzen, Threadripper and EPYC CPUs and Radeon GPUs compete with Intel and NVIDIA. For A+, know that AMD CPUs use their own sockets (such as AM4 and AM5) and are not interchangeable with Intel sockets. 220-1201 3.0 (Hardware)

APAccess Point

The device that lets wireless clients join a wired network, bridging Wi-Fi to Ethernet. Enterprise APs are often powered over PoE and managed by a controller; a rogue AP is one plugged in without authorization.

APFSApple File System

Apple's default file system for macOS (since High Sierra), iOS and iPadOS, built for SSDs with snapshots, strong encryption and space sharing between volumes. Windows cannot read it natively. 220-1202 1.0 (Operating Systems)

APIPAAutomatic Private Internet Protocol Addressing

The fallback that gives a Windows host a self-assigned link-local address in 169.254.0.0/16 when no DHCP server answers. Seeing a 169.254.x.x address means the client could not reach DHCP; it can talk only on the local subnet. 220-1201 2.0 (Networking)

ARMAdvanced RISC [Reduced Instruction Set Computer] Machine

A processor architecture with a reduced instruction set, prized for low power draw. It runs phones, tablets, Raspberry Pi, Apple Silicon Macs and Windows on ARM devices; software compiled for x86/x64 needs emulation or a native build to run on it. 220-1201 3.0 (Hardware)

ATXAdvanced Technology Extended

The standard motherboard form factor (305 x 244 mm) with its matching power supply and case layout. The smaller microATX and Mini-ITX boards use a subset of the same mounting holes, so a full ATX case usually accepts them, but not the reverse. 220-1201 3.0 (Hardware)

AUPAcceptable Use Policy

The policy users accept that states what they may and may not do with company systems, networks and data. 220-1202 4.0 (Operational Procedures)

BECBusiness Email Compromise

A fraud where an attacker impersonates or takes over a business email account, typically an executive or supplier, to redirect payments or obtain sensitive data. 220-1202 2.0 (Security)

BIOSBasic Input/Output System

Legacy firmware that initializes hardware and starts the operating system. Modern systems use UEFI, which adds Secure Boot. 220-1201 3.0 (Hardware); 220-1202 2.0 (Security)

BNCBayonet Neill-Concelman

The twist-locking coaxial connector used on older 10BASE2 thinnet networks and still found on test equipment and some video gear. Its bayonet collar is what distinguishes it from the screw-on F-type connector used for cable TV and cable modems.

BSODBlue Screen of Death

The Windows stop-error screen shown when the kernel hits a fault it cannot recover from, often a driver, memory or storage problem. Note the stop code, check recently added drivers or hardware, and test RAM; the macOS equivalent is a kernel panic. 220-1202 3.0 (Software Troubleshooting)

BYODBring Your Own Device

A model where employees use personal devices for work. It raises questions of data separation, MDM enrolment and what the company may wipe. 220-1201 1.0 (Mobile Devices); 220-1202 2.0 (Security)

CACCommon Access Card

A smart card issued by the US Department of Defense that holds certificates for logging in, signing and encrypting email; it is the classic example of a smart card used for multifactor authentication. CompTIA's A+ list prints it as "Calling-card Authorization Computer".

CIFSCommon Internet File System

The older Microsoft dialect of the SMB file-sharing protocol for Windows shares and printers. The names are now used loosely as synonyms; modern SMB uses TCP 445, legacy CIFS over NetBIOS used 139, and SMB 1.0/CIFS should be disabled as insecure. 220-1201 2.0 (Networking)

CMDBConfiguration Management Database

The database that records every configuration item (servers, network devices, software, licenses) and how they relate. Change management and incident response rely on it to see what a change or outage will affect. 220-1202 4.0 (Operational Procedures)

CNAMECanonical Name

A DNS record that makes one name an alias for another, for example www.example.com pointing to example.com. The alias inherits the target's A/AAAA records; a domain's root (apex) cannot be a CNAME, and a name with a CNAME should carry no other records. 220-1201 2.0 (Networking)

CPUCentral Processing Unit

The processor that executes instructions. A+ asks about cores and threads, clock speed, cache, socket types (Intel LGA vs AMD AM4/AM5), virtualization support and cooling; overheating from a failed fan or dried thermal paste causes throttling and random shutdowns. 220-1201 3.0 (Hardware); 220-1201 5.0 (Hardware and Network Troubleshooting); 220-1202 1.0 (Operating Systems)

DB-9Serial Communications D-Shell Connector, 9 pins

The 9-pin D-shaped connector used for RS-232 serial ports, still found on switch and router console cables and industrial gear, usually paired with a USB-to-serial adapter today. The strictly correct name for the shell size is DE-9, but DB-9 is the common term.

DDoSDistributed Denial of Service

A denial-of-service attack launched from many sources at once, often a botnet, so blocking a single address does not stop it. 220-1202 2.0 (Security)

DDRDouble Data Rate

The family of SDRAM (DDR3, DDR4, DDR5) that transfers data on both the rising and falling edge of the clock. Each generation uses a different slot and voltage, so modules are not interchangeable; match the motherboard's supported type and speed. 220-1201 3.0 (Hardware)

DHCPDynamic Host Configuration Protocol

The protocol that automatically assigns IP addresses and network settings to devices. A rogue DHCP server can redirect traffic; DHCP snooping on switches blocks it. 220-1201 2.0 (Networking)

DIMMDual In-line Memory Module

The full-size memory module used in desktops and servers, with separate contacts on each side. Laptops and small-form-factor systems use the shorter SO-DIMM instead; both must match the DDR generation of the board. 220-1201 3.0 (Hardware)

DKIMDomainKeys Identified Mail

An email authentication method in which the sending domain signs messages with a private key and publishes the public key in DNS, so receivers can verify the message was not altered. 220-1201 2.0 (Networking)

DLPData Loss Prevention

Controls that detect and block sensitive data leaving where it should stay, for example via email, uploads or USB drives. 220-1202 2.0 (Security)

DMARCDomain-based Message Authentication, Reporting, and Conformance

An email policy published in DNS that tells receivers what to do (none, quarantine or reject) with messages that fail DMARC, meaning neither SPF nor DKIM passes in alignment with the visible From domain, and where to send reports. 220-1201 2.0 (Networking)

DNSDomain Name System

The system that translates names such as example.com into IP addresses. Attacks include cache poisoning and tunnelling; DNSSEC adds signed records. 220-1201 2.0 (Networking); 220-1202 1.0 (Operating Systems); 220-1202 2.0 (Security)

DoSDenial of Service

An attack that makes a service unavailable by exhausting its bandwidth, connections or resources, or by crashing it. 220-1202 2.0 (Security)

DRMDigital Rights Management

Technology that controls how licensed digital content and software may be copied, played or installed, for example activation keys, license servers and encrypted media. For technicians, DRM explains why some content will not play after a hardware change or on unapproved devices. 220-1202 4.0 (Operational Procedures)

DSLDigital Subscriber Line

Broadband internet carried over ordinary copper telephone lines. ADSL offers faster download than upload, and speed drops with distance from the provider's equipment. A DSL modem connects to the phone jack, with filters on handsets to remove line noise. 220-1201 2.0 (Networking)

DVIDigital Visual Interface

A video connector for monitors that exists in digital (DVI-D), analog (DVI-A) and combined (DVI-I) versions, plus single- and dual-link variants for higher resolutions. It carries no audio; passive adapters convert DVI-D to HDMI and DVI-A/I to VGA. 220-1201 3.0 (Hardware)

ECCError-correcting Code

Memory that stores extra bits to detect and correct single-bit errors on the fly, used in servers and workstations where silent data corruption is unacceptable. It needs a motherboard and CPU that support it and costs more than non-ECC RAM. 220-1201 3.0 (Hardware)

EDREndpoint Detection and Response

Endpoint software that records activity on hosts, detects suspicious behaviour and lets responders investigate and isolate a machine remotely. 220-1202 2.0 (Security)

EFSEncrypting File System

The Windows feature that encrypts individual files and folders on NTFS volumes, tied to the user's account and certificate. Unlike BitLocker, which encrypts the whole drive, EFS protects per-user data; losing the key or profile without a backup makes the files unrecoverable. 220-1202 2.0 (Security)

EOLEnd-of-life

The vendor's announcement that a product is no longer sold or developed. Devices past EOL may still work, but the next stage, end of support, means no more patches, and running them becomes a security and compliance risk. 220-1202 1.0 (Operating Systems); 220-1202 2.0 (Security)

eSATAExternal Serial Advanced Technology Attachment

An external port that carries the SATA interface to an outside enclosure at full SATA speed, with no USB conversion in between. It supplies no power, so drives need their own supply (eSATAp combined both); USB 3.x and Thunderbolt have largely replaced it. 220-1201 3.0 (Hardware)

ESDElectrostatic Discharge

A sudden transfer of static electricity that can silently damage chips at voltages too low to feel. Use an antistatic wrist strap, mat and bags, touch the chassis before handling parts, and keep humidity moderate; dry air makes static worse. 220-1202 4.0 (Operational Procedures)

EULAEnd-user License Agreement

The license contract a user accepts to install or use software. It defines what you may do (number of installs, personal vs commercial use, no reverse engineering) and makes clear that you are licensing the software, not buying it. 220-1202 4.0 (Operational Procedures)

exFATExtended File Allocation Table

Microsoft's file system for flash drives and SD cards, which removes FAT32's 4 GB file-size limit while staying readable by Windows, macOS and most cameras and consoles. It lacks NTFS features such as permissions, journaling and encryption. 220-1202 1.0 (Operating Systems)

FATFile Allocation Table

The simple, old Microsoft file system family (FAT12, FAT16, FAT32) that tracks disk clusters in a table. It has no permissions, journaling or encryption but is read by almost every device, so it survives on removable media and EFI boot partitions. 220-1202 1.0 (Operating Systems)

FAT3232-bit File Allocation Table

The 32-bit version of FAT, still used on USB sticks, memory cards and the EFI system partition because every OS can read it. Its limits matter on the exam: no single file over 4 GB, and Windows' graphical format tool won't create FAT32 volumes over 32 GB.

FRTFacial Recognition Technology

Biometric authentication that identifies a person from the geometry of their face, as in Windows Hello or Face ID. It is convenient but can be affected by lighting, masks or aging and raises privacy concerns; a PIN or password remains as fallback. 220-1202 2.0 (Security)

FTPFile Transfer Protocol

The classic protocol for transferring files, using TCP 21 for commands and 20 for data in active mode. It sends credentials and files in cleartext, so use SFTP (over SSH, port 22) or FTPS (TLS) instead; passive mode helps through firewalls and NAT. 220-1201 2.0 (Networking)

GFSGrandfather-Father-Son

A backup rotation scheme that keeps daily (son), weekly (father) and monthly (grandfather) sets, so recent restores are granular while older restore points still exist on fewer media. It balances retention depth against storage and tape cost. 220-1202 4.0 (Operational Procedures)

GPSGlobal Positioning System

The satellite system that lets a device compute its position and precise time. On mobile devices it drives location services and find-my-device features; network gear uses GPS receivers as a reference clock for NTP servers. 220-1201 1.0 (Mobile Devices)

GPTGUID [Globally Unique Identifier] Partition Table

The modern partition table that replaced MBR, supporting disks over 2 TB and up to 128 partitions in Windows, with a backup copy of the table for recovery. Booting from a GPT disk requires UEFI; legacy BIOS boot needs MBR. 220-1202 1.0 (Operating Systems)

GUIDGlobally Unique Identifier

A 128-bit value, written as 32 hex digits in five groups, generated so that each one is practically certain to be unique without a central registry. Windows uses GUIDs to identify partitions, devices, COM objects and registry entries. 220-1202 1.0 (Operating Systems)

HDDHard Disk Drive

A storage drive with spinning magnetic platters and a moving read/write head, rated in RPM (5,400, 7,200, 10,000). It offers cheap capacity but is slower and more fragile than an SSD; clicking noises and S.M.A.R.T. warnings signal impending failure. 220-1201 1.0 (Mobile Devices)

HDMIHigh-Definition Multimedia Interface

The standard digital connector that carries video and audio together to monitors and TVs, in full-size, mini and micro forms; newer versions add bandwidth for 4K and 8K at high refresh rates. The real name is High-Definition Multimedia Interface; CompTIA's list prints it as "High-definition Media Interface". 220-1201 3.0 (Hardware)

HSMHardware Security Module

A tamper-resistant hardware device that generates, stores and uses cryptographic keys so they never leave it in plain form. Enterprises use HSMs for certificate authorities, code signing and payment systems; a TPM is the smaller, built-in equivalent for a single PC. 220-1201 3.0 (Hardware)

HTTPHypertext Transfer Protocol

The protocol browsers use to fetch web pages, on TCP port 80. It is cleartext, so anyone on the path can read or alter traffic; modern sites redirect to HTTPS, and HTTP is also a common management interface on network devices. 220-1201 2.0 (Networking)

HTTPSHypertext Transfer Protocol Secure

HTTP carried inside TLS on TCP port 443, encrypting traffic and letting the browser verify the server's certificate. Certificate warnings mean the name, date or issuer did not check out; most web management consoles and cloud APIs use it. 220-1201 2.0 (Networking)

IaaSInfrastructure as a Service

The cloud model where the provider supplies virtual machines, storage and networking and you install, run and patch the operating systems and software yourself, as with Amazon EC2 or Azure VMs. It gives the most control of the three models but also the most responsibility. 220-1201 4.0 (Virtualization and Cloud Computing)

IAMIdentity Access Management

Identity and access management: the processes and tools that create identities, authenticate them and control what they can access. Identity logs are a key source of indicators of compromise. 220-1202 2.0 (Security)

IMAPInternet Message Access Protocol

The email retrieval protocol that keeps messages on the server and syncs folders and read status across devices, on TCP 143 or 993 with TLS, unlike POP3, which downloads mail to one device. The real name is Internet Message Access Protocol; CompTIA's list prints it as "Internet Mail Access Protocol". 220-1201 2.0 (Networking)

IOPSInput/Output Operations Per Second

A measure of how many read or write operations a storage device completes per second, which matters more than raw throughput for databases, virtualization and boot times. NVMe SSDs reach hundreds of thousands of IOPS; a hard drive manages a few hundred. 220-1201 5.0 (Hardware and Network Troubleshooting)

IoTInternet of Things

Everyday devices with network connections: cameras, thermostats, smart speakers, light bulbs, locks. They often ship with default passwords and get few updates, so change credentials, keep firmware current and place them on a separate VLAN or guest network. 220-1201 2.0 (Networking)

IPInternet Protocol

The protocol that addresses and routes packets between networks. In logs and investigations, source and destination IP addresses are key evidence. 220-1201 2.0 (Networking); 220-1202 1.0 (Operating Systems); 220-1202 2.0 (Security)

IPSIn-plane Switching

A system placed inline that inspects traffic and blocks attacks in real time. It is active, so a false positive can block legitimate traffic. 220-1201 3.0 (Hardware)

ISOInternational Organization for Standardization

The International Organization for Standardization. ISO/IEC 27001 and 27002 are the information security standards most often cited in frameworks and audits. 220-1202 1.0 (Operating Systems)

ITXInformation Technology eXtended

A family of small motherboard form factors; Mini-ITX (170 x 170 mm) is the one you will meet, used in compact and home-theater PCs. It fits standard ATX cases through shared mounting holes but typically offers one expansion slot and fewer memory slots. 220-1201 3.0 (Hardware)

KVMKeyboard-Video-Mouse

A switch that lets one keyboard, monitor and mouse control several computers, selected with a button or hotkey. In data centers, IP-based KVMs give remote console access even when the OS is down; do not confuse it with the Linux KVM hypervisor.

LANLocal Area Network

A network covering a limited area such as an office or a home, usually segmented further with VLANs. 220-1201 2.0 (Networking)

LCLucent Connector

A small square fiber-optic connector with a push-pull latch, half the size of SC, and the standard on SFP transceivers. It usually comes as a duplex pair for transmit and receive; keep the ends capped and clean them before plugging in. 220-1201 3.0 (Hardware)

LCDLiquid Crystal Display

The flat-panel display type that uses liquid crystals in front of a backlight to form the image. Modern panels use LED backlights; IPS gives better colors and viewing angles, TN faster response. A very dim screen that still shows a faint image points to backlight failure. 220-1201 3.0 (Hardware)

LDAPLightweight Directory Access Protocol

A protocol for querying and changing directory services such as Active Directory. LDAPS protects it with TLS. 220-1201 2.0 (Networking)

LEDLight-emitting Diode

A semiconductor that emits light efficiently and lasts long. It backlights almost all current LCD monitors, drives the status and link lights on network gear whose color and blink patterns are a first troubleshooting clue, and signals power or error states on motherboards and printers. 220-1201 3.0 (Hardware); 220-1201 5.0 (Hardware and Network Troubleshooting)

MACMedia Access Control

The Layer 2 addressing and access method of Ethernet and Wi-Fi. A MAC address is a 48-bit hardware identifier (the first half is the vendor OUI) that switches use to forward frames; it can be spoofed, so MAC filtering is weak security. 220-1201 2.0 (Networking)

MANMetropolitan Area Network

A network spanning a city or campus, larger than a LAN but smaller than a WAN, usually built on fiber or metro Ethernet from a carrier. It connects an organization's sites within one metro area at near-LAN speeds. 220-1201 2.0 (Networking)

MBRMaster Boot Record

The legacy partition scheme and boot sector at the start of a disk. It is limited to 2 TB disks and four primary partitions (or three plus an extended one), and it is what legacy BIOS boots from; GPT with UEFI replaces it. 220-1202 1.0 (Operating Systems)

MDMMobile Device Management

Tools that enrol, configure and secure mobile devices centrally, for example by enforcing a screen lock, encryption and remote wipe. 220-1201 1.0 (Mobile Devices); 220-1202 2.0 (Security)

MDRManaged Detection and Response

A subscription service in which an outside provider monitors your endpoints and network around the clock, investigates alerts and responds to incidents on your behalf. It gives small IT teams a security operations capability without building a SOC. 220-1202 2.0 (Security)

MFAMultifactor Authentication

Authentication with two or more different factor types, such as something you know, have or are. Two passwords are still one factor. 220-1202 2.0 (Security)

MMCMicrosoft Management Console

The Windows framework that hosts administrative tools as snap-ins in one window: Device Manager, Event Viewer, Disk Management, Local Users and Groups, Services and more. Run mmc.exe to build a custom console or open the .msc files directly. 220-1202 1.0 (Operating Systems)

MNDAMutual Non-Disclosure Agreement

A confidentiality agreement in which both parties promise not to disclose each other's sensitive information, used when a customer and vendor exchange details during a project. Technicians should know that an NDA covers what they see on site. 220-1202 4.0 (Operational Procedures)

mSATAMini-serial Advanced Technology Attachment

A small internal SSD card that plugs into a dedicated slot and speaks the SATA protocol, once common in laptops and small PCs. It has been superseded by M.2, which looks similar but uses a different connector and can also run NVMe. 220-1201 3.0 (Hardware)

MSDSMaterial Safety Data Sheet

The document that lists a chemical's hazards, safe handling, storage and disposal rules, needed for items such as toner, cleaning solvents and batteries. The current standard term is SDS (Safety Data Sheet); the content and purpose are the same. 220-1202 4.0 (Operational Procedures)

MXMail Exchange

The DNS record that names the mail server or servers responsible for a domain, each with a priority value where lower is preferred. Sending servers look up the MX record to deliver mail; a missing or wrong MX means inbound email bounces. 220-1201 2.0 (Networking)

NDANon-Disclosure Agreement

A legal agreement that obliges the signer to keep specified information confidential. 220-1202 4.0 (Operational Procedures)

NetBIOSNetwork Basic Input/Output System

A legacy Windows API for name resolution and session services on a local network, carried over TCP/IP on ports 137, 138 and 139. Modern SMB uses port 445 directly; NetBIOS computer names are limited to 15 characters. 220-1201 2.0 (Networking)

NFCNear-field Communication

Very short-range wireless communication used for contactless payments and badges. Its short range limits, but does not remove, skimming and relay attacks. 220-1201 1.0 (Mobile Devices); 220-1201 2.0 (Networking); 220-1202 3.0 (Software Troubleshooting)

NICNetwork Interface Card

The hardware that connects a device to a network. Each NIC has a MAC address. 220-1201 2.0 (Networking); 220-1201 3.0 (Hardware)

NTFSNew Technology File System

The default Windows file system. It supports file and folder permissions, EFS encryption, compression, journaling and files larger than 4 GB, none of which FAT32 offers. Converting FAT32 to NTFS keeps the data; going back requires a reformat. 220-1202 1.0 (Operating Systems); 220-1202 2.0 (Security)

NTPNetwork Time Protocol

Synchronizes device clocks with a reference time source over UDP port 123, using stratum levels (stratum 0 is the atomic or GPS clock itself). Skewed clocks break Kerberos authentication, certificate validation and log correlation. 220-1201 2.0 (Networking)

NVMeNon-volatile Memory Express

A storage interface designed for flash: the SSD attaches over PCIe lanes, usually in the M.2 form factor, with far more command queues and lower latency than SATA. An M.2 slot can be SATA or NVMe, so check which the motherboard supports before buying. 220-1201 3.0 (Hardware)

OLEDOrganic Light-emitting Diode

A display panel in which each pixel emits its own light, so no backlight is needed. Blacks are true black and contrast is very high, but panels can suffer burn-in from static images and cost more than IPS or VA LCDs. 220-1201 3.0 (Hardware)

ONTOptical Network Terminal

The device at the customer end of a fiber-to-the-home link that converts the optical signal to Ethernet for the home router. It is the fiber equivalent of a cable or DSL modem and is usually supplied and managed by the ISP. 220-1201 2.0 (Networking)

OSOperating System

The operating system: the core software that manages hardware and runs applications. Hardening, patching and secure configuration baselines apply to it. 220-1201 3.0 (Hardware); 220-1201 4.0 (Virtualization and Cloud Computing); 220-1201 5.0 (Hardware and Network Troubleshooting); 220-1202 1.0 (Operating Systems); 220-1202 2.0 (Security); 220-1202 3.0 (Software Troubleshooting)

OTPOne-time Password/Passcode

A one-time password valid for a single login or a short time window, generated by an app or token (TOTP/HOTP) or sent by message. 220-1202 2.0 (Security)

PaaSPlatform as a Service

A cloud model where the provider runs the servers, operating system and runtime, and you deploy only your application code and data. It sits between IaaS (you manage the OS) and SaaS (you manage only your data and users). 220-1201 4.0 (Virtualization and Cloud Computing)

PAMPrivileged Access Management

Privileged access management: controls for admin accounts, such as vaulting credentials, just-in-time access, session recording and approval workflows. 220-1202 2.0 (Security)

PANPersonal Area Network

A very short-range network around one person, linking devices such as a phone, earbuds, smartwatch or keyboard. Bluetooth is the typical PAN technology; NFC and USB tethering also count. 220-1201 2.0 (Networking)

PCPersonal Computer

A general-purpose computer for one user, whether desktop, laptop or all-in-one. On the exam it is the system you build, upgrade and troubleshoot: CPU, RAM, storage, power supply, motherboard and peripherals. 220-1202 3.0 (Software Troubleshooting); 220-1202 4.0 (Operational Procedures)

PCIPeripheral Component Interconnect

A legacy expansion-card bus with a shared parallel 32-bit data path. PCIe, which uses independent serial lanes, replaced it; a PCI card does not fit a PCIe slot, and very few modern motherboards still include PCI slots. 220-1201 3.0 (Hardware)

PCIePeripheral Component Interconnect Express

The serial expansion bus used by modern graphics cards, NVMe drives and add-in cards. Bandwidth scales with lane count (x1, x4, x8, x16) and generation, each generation roughly doubling per-lane speed. A card with fewer lanes works in a longer slot. 220-1201 3.0 (Hardware)

PIIPersonally Identifiable Information

Personally identifiable information: data that identifies a person, such as name, address or ID numbers. A breach involving it can trigger legal notification duties. 220-1202 2.0 (Security); 220-1202 4.0 (Operational Procedures)

PINPersonal Identification Number

A short numeric code used to unlock a device, SIM card or Windows Hello sign-in. A Windows Hello PIN is tied to the specific device and never leaves it, which is why Windows prefers it to a password; still pair it with lockout after failed attempts. 220-1201 1.0 (Mobile Devices); 220-1202 2.0 (Security)

PIVPersonal Identity Verification

A smart card standard for US federal employees and contractors, carrying certificates and a photo for both building access and computer login. On the exam it is an example of a something-you-have factor in multifactor authentication.

PoEPower over Ethernet

Delivers DC power over the same twisted-pair cable as Ethernet data, so access points, IP phones and cameras need no separate outlet. Standards: 802.3af (15.4 W), 802.3at PoE+ (30 W), 802.3bt (60 or 100 W). Power comes from a PoE switch or an injector. 220-1201 2.0 (Networking)

POPPost Office Protocol

An email retrieval protocol (POP3) that downloads messages to one client, usually deleting them from the server. Port 110, or 995 with TLS. For mail kept in sync across several devices, IMAP is the right choice. 220-1201 2.0 (Networking)

POSTPower-on Self-test

The hardware check firmware runs when the computer powers on, before the operating system loads. Failures are reported with beep codes, LED patterns or on-screen messages; no POST at all points to the power supply, motherboard, CPU or RAM. 220-1201 5.0 (Hardware and Network Troubleshooting)

PUPPotentially Unwanted Program

Software the user technically agreed to install but did not really want, such as toolbars, bundled adware or system optimizers. Antimalware tools often flag PUPs separately from malware; teaching users to decline bundled extras prevents most of them. 220-1202 2.0 (Security)

RADIUSRemote Authentication Dial-in User Server

An AAA protocol that lets network devices such as wireless controllers, VPNs and switches check user credentials against a central server. UDP ports 1812 (authentication) and 1813 (accounting); it is the back end for WPA-Enterprise and 802.1X. 220-1202 2.0 (Security)

RAIDRedundant Array of Independent Disks

Combining several drives into one logical volume for speed, redundancy or both. RAID 0 stripes with no redundancy, 1 mirrors, 5 stripes with parity (three drives minimum, survives one failure), 10 mirrors then stripes. RAID is not a backup. 220-1201 3.0 (Hardware); 220-1201 5.0 (Hardware and Network Troubleshooting)

RAMRandom-access Memory

The volatile working memory where the CPU holds running programs and data; its contents are lost when power is removed. Know that DDR4 and DDR5 are not interchangeable, how dual-channel pairing works, SODIMM for laptops and ECC for servers. 220-1201 1.0 (Mobile Devices); 220-1201 3.0 (Hardware); 220-1201 5.0 (Hardware and Network Troubleshooting); 220-1202 1.0 (Operating Systems)

RDPRemote Desktop Protocol

Microsoft's protocol for a remote graphical session on a Windows machine, on TCP port 3389. Never expose it directly to the internet: use a VPN or gateway, enable Network Level Authentication and restrict which accounts can connect. 220-1201 2.0 (Networking); 220-1202 1.0 (Operating Systems); 220-1202 4.0 (Operational Procedures)

ReFSResilient File System

Microsoft's newer file system for data volumes, built for integrity: it checksums metadata, repairs corruption automatically on Storage Spaces mirrors and handles very large volumes. Windows cannot boot from it, so NTFS remains the system drive. 220-1202 1.0 (Operating Systems)

RFIDRadio-frequency Identification

Tags that reply with a stored identifier when energized by a reader's radio field, used in access badges, asset tracking and inventory. Passive tags need no battery. Badge cloning is a risk, so sensitive doors should use encrypted cards plus a PIN. 220-1201 2.0 (Networking)

RJ11Registered Jack Function 11

The small modular connector on telephone cords and DSL modems, with six positions but usually only two or four wires in use. It fits loosely into an RJ45 jack, so check for a wrong plug before assuming an Ethernet port is faulty. 220-1201 3.0 (Hardware)

RJ45Registered Jack Function 45

The eight-position modular plug on twisted-pair Ethernet cables. Pins follow the T568A or T568B color order; use the same standard at both ends for a straight-through cable. Strictly the connector is an 8P8C, but exams call it RJ45. 220-1201 3.0 (Hardware)

RMMRemote Monitoring and Management

Software that managed service providers install on client computers to monitor health, push patches and scripts, and open remote sessions without a user present. Because it grants broad access, attackers abuse stolen RMM credentials; protect them with MFA. 220-1202 4.0 (Operational Procedures)

RSRRapid Security Response

Apple's mechanism for shipping urgent security fixes to iOS, iPadOS and macOS between regular updates, installed quickly without a full OS version change. The installed version shows a letter suffix, such as 16.4.1 (a). 220-1202 1.0 (Operating Systems)

S.M.A.R.TSelf-monitoring Analysis and Reporting Technology

Built-in drive self-monitoring that tracks attributes such as reallocated sectors, pending sectors and temperature and can warn before a failure. A SMART warning means back up now and replace the drive; a clean result does not guarantee the drive is healthy. 220-1201 5.0 (Hardware and Network Troubleshooting)

SaaSSoftware as a Service

Software as a service: complete applications delivered over the internet. The provider runs the stack; the customer still manages data, identities and access. 220-1201 4.0 (Virtualization and Cloud Computing)

SAMLSecurity Assertions Markup Language

An XML-based standard for exchanging authentication assertions between an identity provider and a service provider. It is common for enterprise web SSO. 220-1202 2.0 (Security)

SANStorage Area Network

A dedicated high-speed network that gives servers block-level access to shared storage, so the storage appears as a local disk. It uses Fibre Channel or iSCSI; a NAS, by contrast, shares files over the regular network with SMB or NFS. 220-1201 2.0 (Networking)

SASSerial Attached SCSI [Small Computer System Interface]

An enterprise drive interface using serial point-to-point links, favored in servers for dual-port drives, longer cables and higher reliability. A SAS controller can also run SATA drives, but a SATA controller cannot run SAS drives. 220-1201 3.0 (Hardware)

SATASerial Advanced Technology Attachment

The standard interface for consumer hard drives and 2.5-inch SSDs, with a 7-pin data cable and a 15-pin power connector. SATA III tops out at 6 Gbps (about 550 MB/s), which is why fast SSDs use NVMe over PCIe instead. 220-1201 3.0 (Hardware)

SCSubscriber Connector

A square push-pull fiber connector with a 2.5 mm ferrule, often seen in duplex pairs on older patch panels and ONTs. Remember the shapes: SC square, ST round bayonet, LC the smaller square used on SFP modules. 220-1201 3.0 (Hardware)

SCADASupervisory Control and Data Acquisition

Supervisory control and data acquisition: systems that monitor and control industrial processes across sites, such as pipelines and power grids. They are a subset of ICS. 220-1201 2.0 (Networking)

SCSISmall Computer System Interface

A legacy parallel interface for connecting drives, tape units and scanners on a shared bus, each with a unique ID and the chain terminated at both ends. Replaced by SAS and SATA, though the SCSI command set lives on in SAS, iSCSI and USB storage. 220-1201 3.0 (Hardware)

SIMSubscriber Identity Module

The small card, or embedded eSIM chip, that holds a subscriber's identity and keys so a phone or cellular laptop can authenticate to a carrier. Swapping the SIM moves the number; SIM-swap fraud at the carrier is a way to intercept SMS codes. 220-1201 1.0 (Mobile Devices)

SLAService-level Agreement

A service-level agreement: a commitment with measurable targets, such as fixing critical vulnerabilities within 15 days. Vulnerability reports track compliance against it. 220-1202 4.0 (Operational Procedures)

SMBServer Message Block

The Windows file and printer sharing protocol, on TCP port 445; macOS and Linux (Samba) use it to reach Windows shares too. SMBv1 is obsolete and was exploited by WannaCry, so disable it and block 445 at the perimeter. 220-1201 2.0 (Networking); 220-1201 3.0 (Hardware)

SMSShort Message Service

Text messaging. It is a channel for smishing, and SMS one-time codes are weaker than app or hardware factors because of SIM swapping. 220-1202 2.0 (Security)

SMTPSimple Mail Transfer Protocol

The protocol that sends email between mail servers and from clients to their server. Port 25 is for server-to-server relay, 587 for authenticated client submission with STARTTLS. SMTP only sends; POP3 or IMAP retrieve mail. 220-1201 2.0 (Networking)

SODIMMSmall Outline Dual In-line Memory Module

The compact memory module used in laptops, mini PCs and some all-in-ones, about half the length of a desktop DIMM. Generations are keyed differently, so DDR4 and DDR5 SODIMMs are not interchangeable even though the slots look alike. 220-1201 3.0 (Hardware)

SOHOSmall Office/Home Office

A small office or home setup, typically one router that combines firewall, switch, wireless access point and DHCP server. Hardening tasks on the exam: change default credentials, update firmware, disable WPS and UPnP, use WPA3 or WPA2, and add a guest network. 220-1201 2.0 (Networking); 220-1202 2.0 (Security)

SOPStandard Operating Procedure

Standard operating procedure: step-by-step instructions for performing a routine task consistently and safely. 220-1202 4.0 (Operational Procedures)

SPFSender Policy Framework

An email authentication record in DNS listing which servers may send mail for a domain. 220-1201 2.0 (Networking)

SPICESimple Protocol for Independent Computing Environments

An open remote-display protocol used mainly with KVM/QEMU virtual machines on Linux, delivering the VM's screen, audio and USB devices to a client. Think of it as the open-source counterpart of RDP for virtual desktops. 220-1202 4.0 (Operational Procedures)

SQLStructured Query Language

Structured Query Language, used to query databases. SQL injection inserts attacker input into queries; parameterized queries prevent it. 220-1202 2.0 (Security)

SSDSolid-state Drive

Storage built on flash memory with no moving parts, giving much faster access, silence and shock resistance compared with a hard drive. Comes as 2.5-inch SATA, M.2 SATA or M.2 NVMe; mSATA is the legacy small form. TRIM and wear leveling keep performance up. 220-1201 1.0 (Mobile Devices); 220-1201 3.0 (Hardware)

SSHSecure Shell

Encrypted remote command-line access and file transfer on TCP port 22, replacing Telnet, which sends everything in plain text. Key-based authentication is stronger than passwords; disable root login and limit who may connect. 220-1201 2.0 (Networking); 220-1202 4.0 (Operational Procedures)

SSIDService Set Identifier

The name a wireless network broadcasts so clients can find and join it. Hiding the SSID is not a security measure, since it is easy to recover from client traffic; several SSIDs on one access point can map to separate VLANs for guests and staff. 220-1202 2.0 (Security)

SSOSingle Sign-on

Single sign-on: one authentication grants access to many applications. It is convenient, but it makes the identity provider a high-value target. 220-1202 2.0 (Security)

STStraight Tip

A round fiber connector with a bayonet twist-lock and a 2.5 mm ferrule, common on older multimode installations. Remember ST as the twist-on connector; SC pushes straight in and LC is the smaller latching one. 220-1201 3.0 (Hardware)

TACACSTerminal Access Controller Access-control System

A family of AAA protocols for authenticating administrators to network devices. The current version, Cisco's TACACS+, uses TCP port 49, encrypts the whole packet and separates authentication from authorization, allowing per-command control; RADIUS encrypts only the password. 220-1202 2.0 (Security)

TCPTransmission Control Protocol

Transmission Control Protocol: connection-oriented transport using the SYN, SYN-ACK, ACK handshake. Flags and ports in TCP traffic are key evidence in network analysis. 220-1201 2.0 (Networking)

TKIPTemporal Key Integrity Protocol

The encryption WPA introduced as a quick fix for broken WEP, running on the same hardware with per-packet keys. It is now considered insecure; choose WPA2 or WPA3 with AES (CCMP) and avoid any mixed TKIP/AES mode. 220-1202 2.0 (Security)

TNTwisted Nematic

The oldest and cheapest LCD panel type, with very fast response times that gamers like, but narrow viewing angles and poor color accuracy. IPS panels offer better color and angles; VA panels offer higher contrast. 220-1201 3.0 (Hardware)

TOTPTime-based One-time Password

A one-time code generated from a shared secret and the current time, usually changing every 30 seconds, by apps such as Google Authenticator or Microsoft Authenticator. Stronger than SMS codes, but device clocks must be in sync for codes to validate. 220-1202 2.0 (Security)

TPMTrusted Platform Module

A security chip, or firmware equivalent, that stores encryption keys and measures the boot process. BitLocker uses it to unlock the drive only when the boot chain is unchanged; Windows 11 requires TPM 2.0. Clearing the TPM destroys the keys it holds. 220-1201 3.0 (Hardware); 220-1202 1.0 (Operating Systems)

UACUser Account Control

The Windows feature that runs even administrators with standard rights and prompts for consent or credentials before a program can make system-wide changes. Leave it on; the secure desktop prompt stops malware from silently elevating. 220-1202 2.0 (Security)

UDPUser Datagram Protocol

A connectionless transport protocol that sends datagrams without handshakes, acknowledgments or retransmission, so it is fast but unreliable. Used where speed matters more than every packet: DNS, DHCP, VoIP, streaming and TFTP. 220-1201 2.0 (Networking)

UEFIUnified Extensible Firmware Interface

The modern firmware that replaced BIOS, with a graphical setup, support for drives larger than 2 TB through GPT partitioning, and Secure Boot, which refuses to load unsigned boot code. UEFI boots from GPT disks; legacy BIOS mode boots from MBR. 220-1201 3.0 (Hardware); 220-1202 1.0 (Operating Systems); 220-1202 2.0 (Security)

UPnPUniversal Plug and Play

Lets devices on a LAN discover each other and ask the router to open inbound ports automatically, with no authentication. Convenient for consoles and smart devices, but malware can use it too; disable it on the SOHO router unless a device genuinely needs it. 220-1202 2.0 (Security)

UPSUninterruptible Power Supply

An uninterruptible power supply: a battery unit that keeps equipment running through short outages and allows a clean shutdown or a generator start. 220-1202 4.0 (Operational Procedures)

USBUniversal Serial Bus

The standard port for peripherals and storage. Removable media can spread malware and carry data out, so it is often restricted by policy or DLP. 220-1201 1.0 (Mobile Devices); 220-1201 3.0 (Hardware); 220-1202 1.0 (Operating Systems); 220-1202 3.0 (Software Troubleshooting)

UTMUnified Threat Management

Unified threat management: a single appliance combining firewall, IPS, antivirus, web filtering and VPN. It is simple to run but is a single point of failure. 220-1201 2.0 (Networking)

VAVertical Alignment

An LCD panel type with liquid crystals aligned vertically, giving deeper blacks and higher contrast than IPS or TN, at the cost of slower response and some color shift at wide angles. Common in curved and large monitors. 220-1201 3.0 (Hardware)

VDIVirtual Desktop Infrastructure

Hosting users' desktops as virtual machines in a data center or cloud and streaming the screen to thin clients or any device. It simplifies patching and keeps data off endpoints, but depends entirely on network connectivity and server capacity. 220-1201 4.0 (Virtualization and Cloud Computing)

VGAVideo Graphics Array

The legacy analog video connector, a blue 15-pin D-sub plug, still found on projectors and older monitors. It carries no audio and loses sharpness at high resolutions; adapters from HDMI or DisplayPort to VGA must actively convert digital to analog. 220-1201 3.0 (Hardware)

VLANVirtual LAN [Local Area Network]

Splits one physical switch into separate logical networks, each its own broadcast domain, so traffic is isolated by department or device type without extra hardware. Traffic between VLANs needs a router or Layer 3 switch; 802.1Q tags carry several VLANs over a trunk. 220-1201 2.0 (Networking)

VNCVirtual Network Computer

A remote desktop protocol. When it is exposed or weakly configured, it is a remote access threat vector. 220-1202 4.0 (Operational Procedures)

VoIPVoice over Internet Protocol

Carrying phone calls as IP packets instead of over circuit-switched lines. Calls are set up with SIP and the voice travels in RTP; they are sensitive to latency and jitter, so QoS and often a separate voice VLAN are standard. 220-1201 5.0 (Hardware and Network Troubleshooting)

VPNVirtual Private Network

An encrypted tunnel over an untrusted network that connects remote users or sites to a private network. It is commonly built with IPSec or TLS. 220-1201 2.0 (Networking); 220-1202 1.0 (Operating Systems); 220-1202 4.0 (Operational Procedures)

VRAMVideo Random-access Memory

Dedicated memory on a graphics card for frame buffers and textures, separate from system RAM. High resolutions and large textures need more of it; integrated graphics borrow system RAM instead, which is why a shared-memory setting appears in UEFI. 220-1202 1.0 (Operating Systems)

WANWide Area Network

A network that spans large distances and links separate sites, usually over carrier circuits or the internet. The exam contrasts it with a LAN (one site) and a MAN (one city); the router's WAN port faces the ISP. 220-1201 2.0 (Networking)

WAPWireless Access Point

The device that bridges wireless clients onto the wired network, broadcasting one or more SSIDs. In a SOHO router it is built in; businesses place many access points on PoE and manage them from a controller, with channels planned to avoid overlap.

WinRMWindows Remote Management

Microsoft's service for remote management over HTTP (port 5985) or HTTPS (5986), used by PowerShell Remoting (Enter-PSSession, Invoke-Command). It is on by default on Windows Server but not on client editions, where you run Enable-PSRemoting first. 220-1202 4.0 (Operational Procedures)

WISPWireless Internet Service Provider

An ISP that delivers internet by fixed wireless, with a directional antenna at the customer site pointed at the provider's tower. Common in rural areas without cable or fiber. CompTIA's list prints it as "Written Internet Service Provider"; the W stands for Wireless. 220-1201 2.0 (Networking)

WLANWireless LAN [Local Area Network]

A local network built on Wi-Fi (IEEE 802.11) instead of cables, with clients connecting through access points. Know the bands (2.4, 5 and 6 GHz), the standards (802.11ac is Wi-Fi 5, 802.11ax is Wi-Fi 6) and that WPA2 or WPA3 should protect it. 220-1201 2.0 (Networking)

WPAWi-Fi Protected Access

The family of Wi-Fi security standards. Original WPA with TKIP was a stopgap after WEP and is now weak; WPA2 brought AES-CCMP; WPA3 adds SAE to resist offline password cracking. Personal uses a shared passphrase, Enterprise authenticates each user via RADIUS. 220-1202 2.0 (Security)

WWANWireless Wide Area Network

Internet access over a cellular network (4G LTE, 5G) through a built-in modem or hotspot, so a laptop or tablet stays connected away from Wi-Fi. It needs a SIM or eSIM and a data plan; coverage and data caps are the usual limits. 220-1202 1.0 (Operating Systems)

XDRExtended Detection and Response

Extended detection and response: it correlates telemetry from endpoints, network, cloud and email to detect and respond across all of them, beyond endpoint-only EDR. 220-1202 2.0 (Security)

XFSExtended File System

A high-performance 64-bit journaling file system from SGI, the default on Red Hat Enterprise Linux and its derivatives. It handles very large files and volumes well but cannot be shrunk once created; ext4 remains the default on Ubuntu and Debian. 220-1202 1.0 (Operating Systems)

XSSCross-site Scripting

A web attack where malicious script is injected into a page that other users view, letting the attacker steal session cookies or act as the victim inside the browser. The fix is for the site to validate input and encode output; users should keep browsers patched. 220-1202 2.0 (Security)

Acronyms and expansions from the CompTIA A+ Core 1 (220-1201) exam objectives and Core 2 (220-1202) exam objectives (v2.0) (acronym list), checked 2 November 2026. Definitions are CertSprint's own.