This free CompTIA A+ cheat sheet covers the essential knowledge you need to memorize before sitting for the Core 1 and Core 2 exams. Whether you are cramming the night before or building a brain dump template, this reference guide distills the most frequently tested concepts into quick-reference tables and concise explanations. Bookmark this page and return to it throughout your study journey — many successful candidates report that having a reliable cheat sheet cuts their last-minute review time in half.
The most effective way to use this cheat sheet is as a brain dump template. When you arrive at the Pearson VUE testing center, you will receive a whiteboard or erasable notepad. As soon as the exam timer starts, spend the first two to three minutes writing down the information from this cheat sheet that you find hardest to remember — typically port numbers, RAID levels, and the troubleshooting methodology. This strategy frees up mental bandwidth for the actual exam questions and reduces the chance of second-guessing yourself on memorization-heavy items.
During your study sessions, use this cheat sheet to identify gaps in your knowledge. If you cannot recall a particular port or command from memory, that topic deserves extra attention. Many candidates print this page and highlight the items they struggle with most, then focus their flashcard sessions on those specific areas.
Port numbers are among the most heavily tested topics on the CompTIA A+ exam. You need to know not only the port number and associated protocol but also whether it uses TCP, UDP, or both. The table below covers the ports that appear most frequently on the exam.
| Port | Protocol | TCP/UDP | Purpose |
|---|---|---|---|
| 20/21 | FTP | TCP | File transfer (20=data, 21=control) |
| 22 | SSH/SFTP | TCP | Secure shell and secure file transfer |
| 23 | Telnet | TCP | Remote access (unencrypted — avoid in production) |
| 25 | SMTP | TCP | Sending outgoing email |
| 53 | DNS | TCP/UDP | Domain name resolution |
| 67/68 | DHCP | UDP | Automatic IP address assignment |
| 80 | HTTP | TCP | Web traffic (unencrypted) |
| 110 | POP3 | TCP | Receiving email (downloads to client) |
| 143 | IMAP | TCP | Receiving email (stays on server) |
| 389 | LDAP | TCP | Directory services (Active Directory) |
| 443 | HTTPS | TCP | Secure web traffic (encrypted) |
| 445 | SMB | TCP | Windows file and printer sharing |
| 3389 | RDP | TCP | Remote Desktop Protocol |
The A+ exam tests your knowledge of command-line utilities extensively, especially on Core 2. You need to know what each command does, the common switches, and the scenarios where you would use them. Below are the commands that appear most frequently on the exam.
| Command | Purpose | Common Switches |
|---|---|---|
ipconfig | Display network configuration | /all, /release, /renew, /flushdns |
ping | Test network connectivity | -t (continuous), -n (count) |
tracert | Trace route to destination | -d (no DNS resolution) |
netstat | Network connection statistics | -a (all), -n (numeric), -b (process) |
nslookup | Query DNS records | -type=mx, -type=a |
sfc /scannow | System file checker — repairs corrupted files | /scannow, /verifyonly |
chkdsk | Check and repair disk errors | /f (fix), /r (recover bad sectors) |
gpupdate | Refresh Group Policy settings | /force |
diskpart | Disk partitioning utility | list disk, select disk, clean, format |
robocopy | Robust file copy with resume | /mir (mirror), /z (restartable) |
CompTIA uses a standardized six-step troubleshooting methodology that appears on every version of the A+ exam. You must memorize these steps in order because exam questions often ask you to identify the correct next step in a troubleshooting scenario. Understanding this framework also helps you approach performance-based questions systematically.
RAID (Redundant Array of Independent Disks) questions appear on the Core 1 exam. You need to know the minimum number of drives, whether the RAID level provides redundancy or performance improvements, and the usable storage capacity for each level.
| RAID Level | Name | Min Drives | Redundancy | Key Feature |
|---|---|---|---|---|
| RAID 0 | Striping | 2 | None | Maximum performance, no fault tolerance |
| RAID 1 | Mirroring | 2 | Full | Exact copy on second drive, 50% usable space |
| RAID 5 | Striping + Parity | 3 | 1 drive | Distributed parity, can lose 1 drive |
| RAID 10 | Mirrored Stripes | 4 | 1 per mirror | Best of RAID 0 + RAID 1 combined |
Hardware troubleshooting forms a significant portion of the Core 1 exam. The following reference covers the most common hardware issues and their diagnostic indicators that you should be prepared to identify on exam day.
The A+ exam requires you to identify various connector types by sight and know their maximum capabilities. Pay special attention to the differences between USB generations and video connector types, as these are common exam topics.
Put this cheat sheet to the test with realistic practice questions.
Start Free Practice Test →Focus on common ports (21, 22, 25, 53, 80, 443, 3389), Windows command-line utilities (ipconfig, sfc, chkdsk, gpupdate), troubleshooting methodology (identify, theory, test, plan, verify, document), connector types (USB-A, USB-C, Lightning, HDMI, DisplayPort), and RAID levels (0, 1, 5, 10). These topics appear frequently across both Core 1 and Core 2 exams.
No. CompTIA does not allow any reference materials inside the testing room. However, you receive a whiteboard or erasable notepad at the Pearson VUE testing center. Many successful candidates perform a brain dump — writing down memorized ports, acronyms, and troubleshooting steps — as soon as the exam clock starts.
The most tested commands include ipconfig (network config), sfc /scannow (system file checker), chkdsk (disk errors), gpupdate /force (group policy refresh), msconfig (boot configuration), diskpart (disk partitioning), robocopy (file copy), and shutdown /r /t 0 (immediate restart). Know both the command syntax and when to use each one.
You should memorize approximately 15-20 common ports. The most critical are FTP (20/21), SSH (22), Telnet (23), SMTP (25), DNS (53), DHCP (67/68), HTTP (80), POP3 (110), IMAP (143), HTTPS (443), SMB (445), LDAP (389), and RDP (3389). Know whether each uses TCP, UDP, or both.
CompTIA A+ tests RAID 0 (striping, no redundancy, best performance), RAID 1 (mirroring, full redundancy, requires 2 drives), RAID 5 (striping with parity, requires minimum 3 drives, can lose 1 drive), and RAID 10 (mirrored stripes, requires minimum 4 drives, combines RAID 0 and RAID 1 benefits).
The official 6-step troubleshooting methodology is: 1) Identify the problem, 2) Establish a theory of probable cause, 3) Test the theory, 4) Establish a plan of action, 5) Verify full system functionality, 6) Document findings. This exact sequence appears on the exam and you should memorize it in order.