Free CompTIA A+ Core Concepts Flashcards

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RAM (Random Access Memory)

Volatile memory; stores data temporarily while computer is on; DDR4/DDR5; measured in GB; more RAM = better multitasking

ROM (Read-Only Memory)

Non-volatile memory; stores firmware/BIOS; cannot be easily modified; retains data without power

SSD vs HDD

SSD: no moving parts, faster, more expensive, uses NAND flash. HDD: spinning platters, cheaper per GB, slower, mechanical failure risk

BIOS vs UEFI

BIOS: legacy firmware, MBR boot, 2TB limit. UEFI: modern replacement, GPT boot, secure boot, faster, supports larger drives

CPU Components

ALU (math/logic), Control Unit (directs operations), Cache (L1/L2/L3 fast memory), Registers (tiny fast storage)

Motherboard Form Factors

ATX (standard, most common), Micro-ATX (smaller), Mini-ITX (smallest); determines case compatibility and expansion slots

PCIe (PCI Express)

High-speed expansion bus; x1, x4, x8, x16 lanes; used for GPUs, SSDs, NICs; each gen doubles bandwidth

RAID Levels

RAID 0: striping (fast, no redundancy). RAID 1: mirroring (redundancy). RAID 5: striping + parity (min 3 drives). RAID 10: mirror + stripe

TCP vs UDP

TCP: connection-oriented, reliable, ordered, slower (HTTP, FTP, email). UDP: connectionless, faster, no guarantee (DNS, streaming, gaming)

OSI Model

7 layers: Physical, Data Link, Network, Transport, Session, Presentation, Application. 'Please Do Not Throw Sausage Pizza Away'

IP Address Classes

Class A: 1-126 (large networks). Class B: 128-191 (medium). Class C: 192-223 (small). Private: 10.x, 172.16-31.x, 192.168.x

Subnet Mask

Determines network vs host portion of IP; /24 = 255.255.255.0 (254 hosts); /16 = 255.255.0.0 (65,534 hosts)

DNS

Domain Name System; translates domain names to IP addresses; port 53; uses UDP primarily; hierarchical (root → TLD → domain)

DHCP

Dynamic Host Configuration Protocol; automatically assigns IP addresses; port 67/68; DORA process: Discover, Offer, Request, Acknowledge

Common Ports

HTTP: 80, HTTPS: 443, FTP: 20/21, SSH: 22, Telnet: 23, SMTP: 25, DNS: 53, RDP: 3389, SMB: 445

Windows Command Line

ipconfig (network info), ping (test connectivity), tracert (trace route), nslookup (DNS query), chkdsk (disk check), sfc /scannow (system files)

Linux Commands

ls (list), cd (change dir), sudo (run as root), chmod (permissions), grep (search text), apt/yum (install packages)

File Systems

NTFS: Windows, permissions, encryption, large files. FAT32: cross-platform, 4GB file limit. ext4: Linux. APFS: macOS

Malware Types

Virus (needs host file), Worm (self-replicating), Trojan (disguised), Ransomware (encrypts files), Spyware (monitors activity), Rootkit (hides deep)

Encryption

Symmetric: same key encrypts/decrypts (AES, DES). Asymmetric: public/private key pair (RSA). Hashing: one-way (SHA, MD5)

802.11 Wi-Fi Standards

802.11n (Wi-Fi 4): 600 Mbps. 802.11ac (Wi-Fi 5): 3.5 Gbps, 5GHz. 802.11ax (Wi-Fi 6): 9.6 Gbps, 2.4/5/6GHz

Troubleshooting Methodology

1) Identify problem 2) Theory of cause 3) Test theory 4) Plan of action 5) Implement 6) Verify 7) Document

Printer Types

Laser: toner, fast, high quality. Inkjet: liquid ink, photo quality, slower. Thermal: heat-sensitive paper, receipts. Impact: dot matrix, carbon copies

Power Supply (PSU)

Converts AC to DC; measured in watts; 80 Plus efficiency ratings; modular vs non-modular cables; ATX 24-pin connector

Display Connectors

HDMI: audio+video, most common. DisplayPort: high refresh, daisy-chain. VGA: analog, legacy. DVI: digital/analog, older. USB-C: modern, versatile

Cloud Computing Models

IaaS (VMs, storage), PaaS (dev platforms), SaaS (apps). Public (shared), Private (dedicated), Hybrid (mix)

Virtualization

Running multiple OS on one physical machine; hypervisor manages VMs; Type 1 (bare metal), Type 2 (hosted); saves hardware costs

Mobile Device Security

Screen lock, remote wipe, full device encryption, MDM (Mobile Device Management), biometrics, app permissions

ESD Prevention

Electrostatic Discharge can damage components; use anti-static wrist strap; touch case metal; work on anti-static mat

Backup Types

Full: everything (slow, complete). Incremental: changes since last backup (fast, complex restore). Differential: changes since last full (moderate)

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