Cheat Sheet
CompTIA Network+ (N10-009) Cheat Sheet
By The Exam Atlas Editorial Team · Verified 2026-05-29
A final-revision summary for Network+ N10-009. Study aid only — no notes in the proctored exam.
OSI model (layer 7 → 1)
Application · Presentation · Session · Transport · Network · Data Link · Physical.
A memory aid: “All People Seem To Need Data Processing.”
Common ports
| Port | Service |
|---|
| 20/21 | FTP |
| 22 | SSH / SFTP |
| 23 | Telnet |
| 25 | SMTP |
| 53 | DNS |
| 67/68 | DHCP |
| 80 / 443 | HTTP / HTTPS |
| 123 | NTP |
| 161/162 | SNMP |
| 3389 | RDP |
Subnetting quick reference
| CIDR | Mask | Hosts |
|---|
| /24 | 255.255.255.0 | 254 |
| /26 | 255.255.255.192 | 62 |
| /27 | 255.255.255.224 | 30 |
| /30 | 255.255.255.252 | 2 |
Troubleshooting methodology (in order)
- Identify the problem
- Establish a theory of probable cause
- Test the theory
- Establish a plan of action
- Implement the solution
- Verify full functionality
- Document findings
FAQ
- Can I use notes in the Network+ exam?
- No. It is proctored. Use this for final revision before exam day only.
Sources
