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CompTIA A+ Cheat Sheet: Quick Reference Guide 2026
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.
Plan your next step
This CompTIA A+ cheat sheet covers the most commonly tested topics: port numbers (21, 22, 23, 25, 53, 80, 443, etc.), cable types (Cat5e, Cat6, fiber), Windows commands (ipconfig, ping, netstat), and troubleshooting methodology. Print this guide for quick reference during your final study sessions.
The CompTIA A+ exams cover an enormous amount of material, and having a quick reference for key facts can significantly improve your study efficiency. This cheat sheet distills the most frequently tested information into a scannable format perfect for last-minute review and memorization.
Use this cheat sheet during your study sessions, not as a replacement for comprehensive learning. Understanding concepts is essential—but quick recall of port numbers, cable specifications, and command syntax will save valuable time on exam day.
Current A+ exam and policy guidance
A+ V15 uses 220-1201 and 220-1202. Both exams must be from the same version. Each allows up to 90 questions in 90 minutes; Core 1 requires 675/900 and Core 2 requires 700/900. Study schedules and preparation budgets on this page are planning examples, not guaranteed outcomes or current price quotes.
Checked September 8, 2026: Core 1 · Core 2 · Retake policy · Scoring policy · Renewal fees.
How to Use This Cheat Sheet
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.
Common Ports and Protocols
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 |
Essential Port Numbers
Well-Known Ports (0-1023):
- 20/21 - FTP (Data/Control)
- 22 - SSH (Secure Shell)
- 23 - Telnet (Unsecure remote access)
- 25 - SMTP (Outgoing email)
- 53 - DNS (Domain Name System)
- 67/68 - DHCP (Server/Client)
- 80 - HTTP (Web traffic)
- 110 - POP3 (Email retrieval)
- 143 - IMAP (Email access)
- 161/162 - SNMP (Network management)
- 389 - LDAP (Directory services)
- 443 - HTTPS (Secure web traffic)
- 445 - SMB (File sharing)
- 3389 - RDP (Remote Desktop)
Email Secure Ports:
- 465/587 - SMTPS (Secure SMTP)
- 993 - IMAPS (Secure IMAP)
- 995 - POP3S (Secure POP3)
Memory Trick: "20-21 FTP, 22 SSH, 23 Tell(net), 25 SMTP, 53 DNS, 80 HTTP, 443 HTTPS"
Protocol Categories
Group ports by function: Email (25, 110, 143, 465, 587, 993, 995), Web (80, 443), Remote (22, 23, 3389), Network Services (53, 67/68, 161, 389, 445)
Essential Windows Commands
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) |
Windows Command-Line Reference
Network Commands:
- ipconfig - Display IP configuration
- ipconfig /all - Detailed network info
- ipconfig /release - Release DHCP lease
- ipconfig /renew - Renew DHCP lease
- ipconfig /flushdns - Clear DNS cache
- ping - Test connectivity
- tracert - Trace route to destination
- nslookup - DNS query tool
- netstat - Network statistics
- netstat -an - All connections, numeric
- pathping - Combination ping/tracert
System Commands:
- sfc /scannow - System File Checker
- chkdsk - Check disk for errors
- dism - Deployment Image Servicing
- gpupdate /force - Force Group Policy update
- tasklist - List running processes
- taskkill /PID - End process by ID
Disk Commands:
- diskpart - Disk partitioning
- format - Format drive
- convert - Convert FAT to NTFS
CompTIA Troubleshooting Methodology
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.
- Identify the problem — Gather information from the user, check logs, replicate the issue, and identify environmental changes
- Establish a theory of probable cause — Start with the simplest explanation first (question the obvious), then consider more complex causes
- Test the theory to determine the cause — If the theory is confirmed, determine next steps; if not, re-establish a new theory or escalate
- Establish a plan of action — Create a solution plan and notify affected users; consider potential side effects of the fix
- Verify full system functionality — Confirm the fix resolved the issue and implement preventive measures if applicable
- Document findings, actions, and outcomes — Record the problem, the cause, and the solution for future reference and knowledge sharing
CompTIA Troubleshooting Methodology
The 6-Step Process (MEMORIZE THIS):
1. Identify the problem
- Gather information from user
- Question users about changes
- Check documentation and logs
- Replicate the problem if possible
2. Establish a theory of probable cause
- Consider obvious causes first
- Research symptoms if needed
- Start with simplest explanation
3. Test the theory
- If confirmed, determine next steps
- If not confirmed, establish new theory
4. Establish a plan of action
- Create implementation plan
- Consider impacts and backout plan
- Get approval if needed
5. Implement the solution or escalate
- Apply the fix
- Escalate if beyond scope
6. Verify full system functionality
- Confirm problem is resolved
- Implement preventive measures
- Document everything
RAID Levels Quick Reference
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 Quick Reference
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.
- POST beep codes: Single beep = normal boot. Continuous beeping = RAM issue. Two short beeps = POST error (check display). No beep + no display = power supply or motherboard failure
- Blue Screen of Death (BSOD): Note the stop code. Common causes include driver conflicts, RAM failures, and disk corruption. Boot into Safe Mode to troubleshoot
- SMART monitoring: Self-Monitoring, Analysis and Reporting Technology detects failing drives. Relocate data immediately if SMART reports errors
- Overheating symptoms: Random shutdowns, thermal throttling, loud fans. Clean dust, reapply thermal paste, verify airflow
- No display output: Check cable connections, verify monitor power, test with known-good cable, try different video port, reseat graphics card
- Slow performance: Check Task Manager for CPU/RAM/disk usage, scan for malware, verify startup programs, check available storage space
Hardware Quick Reference
RAM Types:
- DDR3 - 1.5V, 240 pins (desktop), 204 pins (laptop)
- DDR4 - 1.2V, 288 pins (desktop), 260 pins (laptop)
- DDR5 - 1.1V, 288 pins, faster speeds
Storage Interfaces:
- SATA - 6 Gbps, 7-pin data, 15-pin power
- NVMe - PCIe connection, 32 Gbps+
- SAS - Enterprise, 12 Gbps
Display Connectors:
- VGA - Analog, 15-pin D-sub (legacy)
- DVI - Digital/Analog, various types
- HDMI - Digital A/V, consumer standard
- DisplayPort - Digital, professional/gaming
- USB-C/Thunderbolt - Multi-purpose
Power Connectors:
- 24-pin ATX - Motherboard main power
- 4/8-pin CPU - CPU auxiliary power
- 6/8-pin PCIe - Graphics card power
- SATA power - 15-pin L-shaped
- Molex - 4-pin legacy
Connector and Cable Types
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.
- USB 2.0: 480 Mbps, Type-A connector, backward compatible
- USB 3.0 (3.1 Gen 1): 5 Gbps, blue Type-A connector or USB-C
- USB 3.1 Gen 2: 10 Gbps, teal Type-A or USB-C
- Thunderbolt 3/4: 40 Gbps, USB-C form factor, lightning bolt icon
- HDMI: Digital video + audio, most common display connector
- DisplayPort: Digital video + audio, supports daisy-chaining monitors
- RJ-45: Ethernet networking, 8-pin connector
- RJ-11: Telephone/modem, 6-pin connector (smaller than RJ-45)
Network Cable Quick Reference
Twisted Pair Categories:
- Cat 5 - 100 Mbps, 100m max
- Cat 5e - 1 Gbps, 100m max (most common legacy)
- Cat 6 - 10 Gbps (55m) / 1 Gbps (100m)
- Cat 6a - 10 Gbps, 100m max
- Cat 7 - 10 Gbps, shielded
- Cat 8 - 25/40 Gbps, data center use
Fiber Optic:
- Single-mode (SMF) - Long distance, laser, small core (8-10 microns)
- Multi-mode (MMF) - Short distance, LED, large core (50-62.5 microns)
Coaxial:
- RG-6 - Cable TV, internet
- RG-59 - Legacy CCTV, short runs
Connector Types:
- RJ-45 - Ethernet twisted pair
- RJ-11 - Telephone
- LC, SC, ST, FC - Fiber connectors
- F-type - Coaxial
Test Your A+ Knowledge
Put this cheat sheet to the test with realistic practice questions.
Start Free Practice Test →Facts and planning estimates
- Port Numbers
- 20+ covered
- Commands
- 30+ listed
- Cable Types
- All major
- Troubleshooting
- 6 steps
Linux/macOS Command Reference
Navigation:
- pwd - Print working directory
- ls - List directory contents
- ls -la - Detailed listing with hidden files
- cd - Change directory
- mkdir - Create directory
- rm - Remove files
- rm -rf - Remove directory recursively
System:
- sudo - Execute as superuser
- chmod - Change permissions
- chown - Change ownership
- ps aux - List all processes
- top/htop - Process monitor
- df -h - Disk space usage
- grep - Search text patterns
- find - Search for files
Network:
- ifconfig - Network configuration (legacy)
- ip addr - Network configuration (modern)
- ssh - Secure shell connection
Study tips
Print this cheat sheet and review it during commutes, lunch breaks, or before bed.
Create flashcards for port numbers—they appear frequently on the exam.
Practice typing commands in a virtual machine to build muscle memory.
Use mnemonics to remember sequences (like troubleshooting steps).
Write out the troubleshooting methodology from memory until it's automatic.
Group related items together when memorizing (all email ports, all network commands, etc.).
Common mistakes to avoid
Memorizing without understanding—know what each port/command actually does.
Focusing only on cheat sheet material instead of comprehensive study.
Not practicing commands hands-on in a lab environment.
Confusing similar items (Cat 5e vs Cat 6, ipconfig vs ifconfig).
Forgetting the troubleshooting methodology—it's heavily tested.
Study perspective
The cheat sheet is for the last 10% of preparation, not the first 90%. Build understanding through comprehensive study, then use quick reference materials to reinforce retention and fill gaps. On exam day, you'll be glad you memorized those port numbers.
Test Your Knowledge of These Topics
Use our practice questions to see how well you've memorized this material.
Frequently Asked Questions
What should I memorize for the CompTIA A+ exam?
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.
Can I bring a cheat sheet into the A+ exam?
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.
What are the most important Windows commands for A+?
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.
How many ports do I need to know for CompTIA A+?
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.
What RAID levels are tested on the A+ exam?
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).
What is the CompTIA troubleshooting methodology?
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.
Can I use a cheat sheet during the A+ exam?
No—you cannot bring any materials into the exam. This cheat sheet is for study and memorization before the test, not for use during.
Which port numbers appear most on the A+ exam?
The most frequently tested ports are 21-22 (FTP/SSH), 25 (SMTP), 53 (DNS), 80/443 (HTTP/HTTPS), 3389 (RDP), and the email ports (110, 143, 465, 993, 995).
Do I need to memorize all these commands?
Focus on the most common: ipconfig, ping, tracert, netstat for networking; sfc, chkdsk for system repair. Know what each does and basic syntax.
How many questions cover troubleshooting methodology?
Troubleshooting methodology appears throughout both exams in various forms. The 6-step process is foundational—memorize it completely.
Should I study Cat 5 if it's outdated?
Yes—A+ tests knowledge of older technologies too. Know the progression from Cat 5 through Cat 8 and their specifications.
Practice & quick reference
- A+ Practice Questions Exam-style questions with explanations
- Free CompTIA A+ Practice Test 2026: 90+ Questions with Explanations Free practice test
- A+ Acronyms
- A+ Flashcards Rapid-recall drilling for ports, terms, and acronyms
- Hardware
- Networking
- Troubleshooting
Study tools & plans
- Study Guide
- Exam Tips
- How to Pass
- 30-Day Plan
- CompTIA A+ Exam Objectives Explained (2026 Domain Guide) Exam objectives
- CompTIA A+ Weekend Study Plan: Certification for Busy Professionals 2026 Study plan
- Certification Overview Complete guide and requirements
- Jobs
Exam facts & renewal
- Passing Score
- CompTIA A+ Renewal: CEUs, Costs & Deadlines (2026) Renewal & CE
- A+ Exam: Up to 90 per exam Questions (2026) How many questions
- Does A+ Expire? 2026 Renewal Guide Does it expire?
- Is CompTIA A+ Hard? Difficulty analysis