CompTIA A+ Core 1 — Master Recall Deck

RAM

Volatile temporary working memory used for programs and data currently being worked on.

SSD

Non-volatile long-term storage that keeps files and data even when power is off.

HDD

Magnetic, non-volatile long-term storage that is generally slower than an SSD.

CPU

Central Processing Unit. Executes instructions and processes data.

Motherboard

Main circuit board that connects computer components and allows them to communicate.

PSU

Power Supply Unit. Supplies electrical power to computer components.

DIMM

Slot/form factor associated with desktop RAM modules.

PCIe x16

Expansion slot commonly used for a graphics card/GPU.

M.2

Slot/form factor commonly used by M.2 SSDs, including NVMe SSDs.

NVMe

High-speed storage protocol commonly used by SSDs over PCIe.

SATA Data Cable

Carries data between a SATA drive and the motherboard.

SATA Power Cable

Provides electrical power from the PSU to a SATA drive.

Form Factor

The physical size, shape, and design of a component or connector.

USB-C

A connector/form factor. The connector alone does not determine all supported speeds or features.

HDMI

Digital connection that can carry video and audio.

IP Address

Logical network address used to identify and address a device on a network.

MAC Address

Hardware/network-interface identity associated with a NIC.

NIC

Network Interface Card or Network Interface Controller. Interface that allows a device to communicate with a network.

DHCP

Dynamic Host Configuration Protocol. Automatically provides network settings, including an IP address.

DNS

Domain Name System. Resolves domain or host names to IP addresses.

APIPA

Automatic Private IP Addressing. A computer can self-assign a 169.254.x.x IPv4 address when normal DHCP configuration is not obtained.

Subnet Mask

Helps determine whether a destination is on the local network or another network.

Default Gateway

Address used to send traffic toward other networks.

Switch

Connects devices within the same local network or LAN.

Router

Routes traffic between different networks.

Access Point (AP)

Provides wireless devices access to a network.

Modem

Connects a network to an Internet Service Provider.

ISP

Internet Service Provider. Provides internet connectivity.

Firewall

Filters network traffic based on rules by allowing or blocking traffic.

Network Port

A logical number used to identify a network service or application.

IPv4

32-bit IP addressing typically written as numbers separated by dots.

IPv6

128-bit IP addressing with a much larger address space, typically written as hexadecimal groups separated by colons.

Private IP Address

IP address used inside local networks and not directly routed across the public internet.

Public IP Address

Internet-routable IP address used across the public internet.

Private IPv4 Range 10

10.x.x.x

Private IPv4 Range 172

172.16.x.x through 172.31.x.x

Private IPv4 Range 192

192.168.x.x

Static IP

IP address manually configured and intended to remain predictable.

Dynamic IP

IP address that can be automatically assigned and can change, commonly through DHCP.

DHCP Lease

DHCP-assigned IP address provided for a period of time and capable of being renewed.

DHCP Reservation

DHCP configuration that gives a particular device a designated IP address, commonly based on its MAC address.

TCP

Transmission Control Protocol. Connection-oriented protocol that provides reliable, ordered delivery with retransmission.

UDP

User Datagram Protocol. Connectionless protocol with lower overhead and no TCP-style delivery guarantee.

TCP vs UDP

TCP emphasizes reliable and ordered delivery. UDP has lower overhead without TCP-style delivery guarantees.

Port vs TCP/UDP

A port identifies which service or application is being used. TCP or UDP describes how the data is transported.

FTP

File Transfer Protocol. Transfers files between computers over a network using TCP ports 20 and 21.

FTP Port 20

TCP port used for FTP data in traditional active FTP.

FTP Port 21

TCP port used for FTP control and commands.

SSH

Secure Shell. Provides secure and encrypted remote access using TCP port 22.

Telnet

Provides insecure remote access using TCP port 23.

SMTP

Simple Mail Transfer Protocol. Used to send or transfer email using TCP port 25.

DNS Port

DNS uses port 53 for name resolution and commonly uses TCP and UDP.

DHCP Server Port

DHCP servers use UDP port 67.

DHCP Client Port

DHCP clients use UDP port 68.

DHCP Ports

DHCP uses UDP ports 67 and 68. Port 67 is used by the server and port 68 by the client.

HTTP

Hypertext Transfer Protocol. Used for web traffic using TCP port 80.

POP3

Post Office Protocol version 3. Retrieves or downloads email using TCP port 110.

NTP

Network Time Protocol. Synchronizes time and clocks between devices on a network using UDP port 123.

IMAP

Internet Message Access Protocol. Accesses and synchronizes email with a mail server using TCP port 143.

HTTPS

Hypertext Transfer Protocol Secure. Used for secure and encrypted web traffic using TCP port 443.

SMB

Server Message Block. Used for network file and printer sharing using TCP port 445.

SMTP vs POP3 vs IMAP

SMTP sends email, POP3 retrieves or downloads email, and IMAP accesses and synchronizes email with a mail server.

SSH vs Telnet

SSH provides secure remote access using TCP port 22. Telnet provides insecure remote access using TCP port 23.

Troubleshooting Step 1 - Identify Problem

Gather information and determine the problem and symptoms.

Troubleshooting Step 2 - Establish Theory

Develop a likely cause of the problem.

Troubleshooting Step 3 - Test Theory

Test whether the suspected cause of the problem is correct.

Troubleshooting Step 4 - Plan/Implement Solution

Create a plan and perform the repair.

Troubleshooting Step 5 - Verify Full Functionality

Confirm the repair worked and the system functions properly.

Troubleshooting Step 6 - Document

Record the problem, cause, solution, and findings.

Test vs Implement

Testing determines whether the theory is correct. Implementing performs the repair.

Implement vs Verify

Implementing performs the fix. Verifying checks whether the fix worked and full functionality was restored.

Device Manager

Windows tool used to view and manage hardware devices and drivers and troubleshoot device or driver issues.

Event Viewer

Windows tool used to view system, application, and security event logs.

ipconfig /all

Windows command that displays detailed IP and network configuration information, including whether DHCP is enabled.

RAM vs SSD

RAM is volatile temporary working memory. An SSD is non-volatile persistent storage.

SATA Data vs SATA Power

SATA Data carries data between a drive and motherboard. SATA Power supplies electricity from the PSU to a drive.

IP vs MAC vs NIC

An IP address is a logical network address, a MAC address identifies a network interface, and a NIC is the interface that connects a device to a network.

Switch vs Router vs AP vs Modem

A switch connects devices on a LAN, a router connects different networks, an access point provides wireless network access, and a modem connects the network to an ISP.

Subnet Mask vs Default Gateway

A subnet mask helps determine whether a destination is local or on another network. A default gateway is used to send traffic toward other networks.

DHCP vs DNS

DHCP automatically provides network configuration. DNS resolves names to IP addresses.

DHCP vs APIPA

DHCP normally provides network configuration. If normal DHCP IPv4 configuration is not obtained, a computer can self-assign an APIPA 169.254.x.x address.

RDP

Remote Desktop Protocol. Used to remotely access and control another computer's graphical desktop. Uses port 3389

LDAP

Lightweight Directory Access Protocol. Used to access directory information such as users, computers, and groups over a network. Uses port 389.

SNMP

Simple Network Management Protocol. Used to monitor and manage network devices. Uses UDP ports 161 and 162. Port 161 is used for queries and port 162 for traps/alerts.

Syslog

Used to send and collect log messages from network devices and systems. Commonly uses UDP port 514.

SFTP

SSH File Transfer Protocol. Used to securely transfer files over a network using SSH. Uses TCP port 22.

FTPS

File Transfer Protocol Secure. Provides secure FTP file transfers using TLS. Commonly uses TCP port 21 for explicit FTPS and TCP port 990 for implicit FTPS.

RADIUS

Remote Authentication Dial-In User Service. Provides centralized authentication, authorization, and accounting (AAA) for network access. Uses UDP port 1812 for authentication/authorization and UDP port 1813 for accounting.

TACACS+

Terminal Access Controller Access-Control System Plus. Provides centralized authentication, authorization, and accounting (AAA), commonly for administrative access to network devices. Uses TCP port 49.

Kerberos

Network authentication protocol that authenticates users and services using tickets. Commonly associated with domain environments. Uses TCP/UDP port 88.

L2TP

Layer 2 Tunneling Protocol. Used for VPN tunneling and does not provide encryption by itself. Commonly paired with IPsec for security. Uses UDP port 1701.

SIP

Session Initiation Protocol. Used to establish, manage, and end communication sessions, especially VoIP calls. Uses TCP/UDP port 5060.

RTP

Real-time Transport Protocol. Used to carry real-time audio and video, commonly for VoIP communications. Typically uses UDP with dynamically selected ports rather than one single fixed port.

SRTP

Secure Real-time Transport Protocol. Securely carries real-time audio and video by providing security and encryption for RTP media. Typically uses UDP with dynamically selected ports rather than one single fixed port.

ICMP

Internet Control Message Protocol. Used for network diagnostic and error-reporting messages and is commonly associated with ping. ICMP uses neither TCP nor UDP and does not use TCP/UDP port numbers.

TFTP

Trivial File Transfer Protocol. Used for simple file transfers over a network and commonly associated with transferring configuration or boot files. Uses UDP port 69 and does not provide secure encrypted file transfer.

CIFS

Common Internet File System. An older implementation of SMB used for network file and printer sharing. Modern SMB commonly uses TCP port 445.

NetBIOS

Network Basic Input/Output System. Associated with older Windows network communication and resource sharing. NetBIOS over TCP/IP (NetBT) uses UDP port 137 for name service, UDP port 138 for datagram service, and TCP port 139 for session service.

AFP

Apple Filing Protocol. Legacy protocol used for Apple/macOS network file sharing. Uses TCP port 548.

SMTP Secure and Submission Ports

SMTP uses TCP port 25 for traditional mail transfer, TCP port 587 for mail submission, and TCP port 465 for SMTP with implicit TLS.