CompTIA A+ flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

SO-DIMM

A small memory module used in laptops and compact devices; DDR4 SO-DIMM has 260 pins, while DDR5 SO-DIMM has 262 pins.

OLED display

A mobile display technology where organic pixels emit their own light; it needs no backlight and produces true black by turning pixels off.

Wi-Fi calling

A feature that routes phone calls over a Wi-Fi network instead of cellular; it requires carrier support and emergency address registration for E911.

MDM

Mobile Device Management software enrolls phones and tablets, enforces policies such as passcodes and encryption, and can remotely wipe corporate data.

USB-C

A reversible connector used for charging and data; it supports alternate modes for video and can deliver power under USB Power Delivery.

Watt-hour formula

Watt-hours equal milliamp-hours multiplied by voltage divided by 1,000; for example, 3,000 mAh at 3.8 V is about 11.4 Wh.

Digitizer

The touch-sensing layer on a mobile screen that converts physical touch into digital coordinates; it is often replaced together with the glass.

APIPA address

A link-local IPv4 address in 169.254.0.0/16 that a device assigns itself when DHCP fails; it cannot route beyond the local network.

DHCP DORA

The four-step DHCP process: Discover, Offer, Request, and Acknowledge; the client obtains an IP address, mask, gateway, and DNS servers.

Private IPv4 ranges

RFC 1918 addresses are 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16; they are not routed on the public internet.

Cat6a cable

A twisted-pair Ethernet cable rated for 10 Gbps up to 100 meters; it has stricter shielding and crosstalk specifications than Cat6.

DNS record types

A maps names to IPv4, AAAA to IPv6, CNAME creates an alias, MX identifies mail servers, and TXT carries text such as SPF records.

Non-overlapping Wi-Fi

In 2.4 GHz Wi-Fi, channels 1, 6, and 11 are commonly used because they do not overlap; 5 GHz has many more non-overlapping channels.

VLAN

A virtual local area network logically segments a switch into separate broadcast domains without requiring separate physical switches.

DDR5 DIMM

A 288-pin desktop memory module with a different notch and higher speed than DDR4; DDR5 and DDR4 are not interchangeable.

M.2 NVMe

A small expansion-card SSD that uses PCIe lanes through the M.2 slot; NVMe reduces latency and supports higher throughput than SATA.

RAID 5

Striping with distributed parity across at least three disks; it survives one disk failure but provides less usable capacity than RAID 0.

ATX 24-pin

The main motherboard power connector; it supplies +3.3 V, +5 V, and +12 V rails and must be fully seated for the system to power on.

UEFI

Modern firmware that initializes hardware before the operating system, supports GPT disks, Secure Boot, and larger boot drives than legacy BIOS.

Laser imaging steps

Charging, exposing, developing, transferring, fusing, and cleaning; each step builds and fixes toner onto paper in a laser printer.

Thermal paste

A compound applied between a CPU and heat sink to fill microscopic gaps and improve heat transfer; excess can insulate instead of help.

Type 1 hypervisor

Bare-metal virtualization software such as ESXi or Hyper-V that runs directly on hardware and hosts virtual machines without a full host OS.

Type 2 hypervisor

Hosted virtualization software such as VirtualBox or VMware Workstation that runs as an application on top of an existing operating system.

IaaS

Infrastructure as a Service provides virtual machines, storage, and networks on demand; the customer manages the guest OS and applications.

SaaS

Software as a Service delivers a complete application over the internet; the provider manages infrastructure, platform, and application updates.

Containers

Lightweight isolated application environments that share the host OS kernel; they start faster and use fewer resources than full virtual machines.

Cloud elasticity

The ability to automatically add or remove computing resources as demand changes, often billed on a pay-as-you-go basis.

POST beep codes

Audible patterns from the motherboard during power-on self-test; the pattern identifies failures such as missing RAM or a video problem.

No boot device

An error when firmware cannot find a bootable disk; check boot order, drive connections, and whether the drive contains an active partition.

IP conflict

Two devices using the same IPv4 address; symptoms include intermittent connectivity, and ipconfig /release then /renew can obtain a new lease.

Spooler

The Windows print service that queues print jobs; restarting it can clear a stuck queue or resolve a printer showing offline.

Degraded RAID

A RAID array running without full redundancy after a disk failure; replace the failed disk and rebuild to restore fault tolerance.