CompTIA A+ key terms

Software that lets an organization enroll, configure, secure, and remotely wipe employee smartphones and tablets from a central console. Policies can enforce screen locks, encryption, and approved apps without the user's hands-on setup.

A policy where employees use their own personal phones, tablets, or laptops for work tasks. IT typically secures corporate data through containers or MDM profiles instead of owning and managing the whole device.

A unique 15-digit number hard-coded into a cellular modem that identifies a specific phone on GSM and LTE/5G networks. Carriers use it to block stolen handsets and to check warranty or activation status.

A soldered chip inside a phone that stores carrier subscription profiles digitally. Users activate or switch carriers by downloading a profile instead of inserting a physical SIM card.

A short-range wireless standard (a few centimeters) used for tap-to-pay, transit cards, and pairing. It operates at 13.56 MHz and can also power passive tags without a battery.

Sharing a phone's cellular data connection with other devices over Wi-Fi, Bluetooth, or a USB cable. Carriers may meter or restrict it, and it drains the battery faster than normal use.

A protocol that automatically assigns IP addresses, subnet masks, default gateways, and DNS servers to devices when they join a network, preventing manual configuration errors and address conflicts.

A hierarchical naming system that translates human-readable hostnames such as example.com into IP addresses machines can route to. Clients query a resolver, which caches answers to speed repeat lookups.

A 32-bit value that tells a device which portion of an IPv4 address identifies the network and which identifies the host, letting it decide whether traffic stays local or goes to the gateway.

The router address a device sends traffic to when the destination IP is outside its own subnet. Without a correct gateway, a host can reach local peers but not the internet.

A logical grouping of switch ports that behaves like a separate network even when the hardware is shared. VLANs reduce broadcast traffic and let administrators segment departments without running new cabling.

A technology that delivers both data and DC power over a single Ethernet cable to devices like access points, cameras, and phones, removing the need for a nearby electrical outlet.

The name a wireless access point broadcasts so clients can find and join its network. Multiple access points can share one SSID to let users roam between them.

The current Wi-Fi security standard, using SAE to resist offline password guessing and providing forward secrecy. It replaces WPA2 and is required for Wi-Fi 6 certification in personal mode.

A router function that rewrites private source IP addresses to a single public address as traffic leaves the network, letting many devices share one internet connection and hiding internal addressing.

An encrypted tunnel that carries traffic between a remote device and a private network over the public internet, protecting data on untrusted Wi-Fi and giving access to internal resources.

A protocol designed for solid-state drives that communicates over the PCIe bus instead of SATA, delivering much higher throughput and lower latency for high-performance storage.

A serial interface for connecting storage drives and optical drives to a motherboard, commonly rated at 6 Gb/s. It replaced older parallel IDE cables with thin, easier-to-route connectors.

Combining multiple physical drives into one logical volume for redundancy, speed, or both. Common levels are RAID 0 (striping), RAID 1 (mirroring), RAID 5 (parity), and RAID 10.

The component that converts AC wall power into the regulated DC voltages a computer's parts need. Its wattage and connector types must match the load and the motherboard's requirements.

A high-speed interface that carries PCIe and DisplayPort over a single USB-C connector, supporting external drives, docks, and monitors. Thunderbolt 3 and 4 reach 40 Gb/s.

A small coin cell on the motherboard that keeps the real-time clock running and preserves BIOS/UEFI settings when the system is unplugged. A dead one causes clock resets and lost configuration.

A compound applied between a CPU and its heatsink to fill microscopic air gaps and improve heat transfer. Too much or too little can raise temperatures and trigger throttling.

Software that creates and runs virtual machines by dividing a host's CPU, memory, and storage among guests. Type 1 runs directly on hardware; Type 2 runs on an operating system.

A software-defined computer with its own virtual CPU, RAM, disk, and network adapter that runs an operating system independently on shared physical hardware, isolated from other guests.

A lightweight, isolated runtime package that bundles an application with its dependencies and shares the host OS kernel, so it starts faster and uses less overhead than a virtual machine.

A cloud model that rents virtual machines, storage, and networking on demand, leaving the customer to install and patch the operating system and applications.

A cloud model where a provider hosts and maintains the entire application, and users access it through a browser or client, paying by subscription rather than owning software.

A deployment that connects private infrastructure with public cloud services, letting workloads move between them while data and identity are shared across both environments.

Virtual Desktop Infrastructure: running each user's desktop operating system on a central server and streaming the screen to a thin client, simplifying patching and data control.

Power-On Self-Test: firmware diagnostics that check CPU, memory, and core devices at boot before handing control to the OS. Beep codes or on-screen errors report failures.

The Windows stop error screen shown when the kernel hits an unrecoverable fault, displaying a stop code and sometimes a failing driver name to guide troubleshooting.

A connector that feeds a port's transmit pins back to its receive pins, used to verify that a network adapter or serial port works without needing a remote device.

A handheld device that checks Ethernet wiring for opens, shorts, crossed pairs, and miswiring. More advanced units measure length and attenuation with a time-domain reflectometer.

A pair of tools that places an audible tone on a cable at one end and detects it with a probe at the other, identifying which run goes to which jack or patch panel port.

A test instrument that measures voltage, resistance, and continuity, used to check power supply output, wall outlets, and cable integrity before replacing components.

Electrostatic discharge: a sudden flow of static electricity that can destroy or degrade chips. Technicians prevent it with wrist straps, mats, and by handling boards by their edges.

A protection mechanism where the CPU or GPU lowers its clock speed when temperatures exceed a safe limit, causing sudden slowdowns that often point to dust, fan failure, or dried paste.