COMPTIA NETWORK+ / CHEAT SHEET Find the network detail.
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Review ports, layers, commands, and subnetting alongside practical troubleshooting.
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CompTIA Network+ Cheat Sheet 2026: Ports, Protocols & Quick Reference
This free Network+ cheat sheet covers every critical concept you need to memorize before sitting for the exam. From port numbers and the OSI model to subnetting formulas and wireless standards, this reference guide distills the most frequently tested material into quick-reference tables. Use it as your brain dump template at the testing center — write down this information on your whiteboard as soon as the exam timer starts, then tackle questions with confidence knowing your reference material is right in front of you.
Current exam and planning guidance
Network+ N10-009 allows up to 90 questions in 90 minutes and requires a scaled score of 720/900. Preparation schedules, salary scenarios, and materials budgets here are planning examples, not verified market prices or guaranteed outcomes. Practice percentages are optional review targets, not official pass predictors.
Provider references checked September 8, 2026: Current exam details and objectives · Retake policy · CE renewal fees.
Plan your next step
This Network+ cheat sheet covers the most tested concepts: OSI model layers, common ports (20-443 and beyond), subnetting quick calculations, troubleshooting commands, and cable specifications. Bookmark this page for quick exam-week review.
This cheat sheet distills the most critical Network+ exam content into a quick-reference format. Use it for final review in the days before your exam, or as a study companion to reinforce key concepts. While this is not a substitute for comprehensive study, it covers the high-frequency topics that appear on most exams.
How to Use This Cheat Sheet Effectively
The most effective study strategy is to review this cheat sheet daily during the final week before your exam. Each day, cover the page and try to reproduce each table from memory. Any items you cannot recall become your focused study targets for that session. On exam day, arrive early and use the waiting time to mentally rehearse your brain dump sequence — most candidates start with the port table, then subnetting, then the OSI model.
Remember that the Network+ exam is not purely memorization. While this cheat sheet helps with recall-based questions, approximately 60% of the exam tests your ability to apply these concepts in scenario-based questions. Use practice tests alongside this reference to build both your factual knowledge and your analytical skills.
Essential Ports and Protocols
Port numbers are the single most memorization-heavy topic on the Network+ exam. You need to know the port number, the associated protocol, whether it uses TCP or UDP (or both), and its function. The exam frequently presents scenarios where you must identify which port to open in a firewall or which protocol is causing a connection issue.
| Port | Protocol | TCP/UDP | Purpose |
|---|---|---|---|
| 20/21 | FTP | TCP | File transfer (20=data, 21=control) |
| 22 | SSH/SFTP/SCP | TCP | Secure shell, 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 (UDP for queries, TCP for zone transfers) |
| 67/68 | DHCP | UDP | Automatic IP address assignment (67=server, 68=client) |
| 80 | HTTP | TCP | Web traffic (unencrypted) |
| 110 | POP3 | TCP | Receiving email (downloads to client) |
| 123 | NTP | UDP | Network Time Protocol — clock synchronization |
| 143 | IMAP | TCP | Receiving email (syncs with server) |
| 161/162 | SNMP | UDP | Network device monitoring and management |
| 389 | LDAP | TCP | Directory services (Active Directory) |
| 443 | HTTPS | TCP | Secure web traffic (TLS encrypted) |
| 445 | SMB | TCP | Windows file and printer sharing |
| 636 | LDAPS | TCP | Secure LDAP over TLS |
| 3389 | RDP | TCP | Remote Desktop Protocol |
Essential Ports and Protocols
Must-Know Ports:
| Port | Protocol | Use |
|---|---|---|
| 20/21 | FTP | File transfer (data/control) |
| 22 | SSH | Secure shell |
| 23 | Telnet | Remote access (insecure) |
| 25 | SMTP | Email sending |
| 53 | DNS | Name resolution |
| 67/68 | DHCP | IP assignment |
| 80 | HTTP | Web (unsecured) |
| 110 | POP3 | Email retrieval |
| 143 | IMAP | Email retrieval |
| 443 | HTTPS | Secure web |
| 3389 | RDP | Remote desktop |
Additional Important Ports:
- 69: TFTP
- 123: NTP
- 161/162: SNMP
- 389: LDAP
- 636: LDAPS
- 445: SMB
- 1433: MSSQL
- 3306: MySQL
- 5060/5061: SIP
TCP vs UDP:
- TCP: Connection-oriented, reliable (HTTP, FTP, SSH)
- UDP: Connectionless, faster (DNS, DHCP, TFTP)
OSI Model Quick Reference
The OSI (Open Systems Interconnection) model is the foundational framework for understanding how network communication works. The Network+ exam tests your ability to identify which layer a given protocol, device, or process operates at. Use the mnemonic "Please Do Not Throw Sausage Pizza Away" to remember the layers from bottom (Layer 1) to top (Layer 7). You should also know the PDU (Protocol Data Unit) at each layer and which devices operate at that layer.
| Layer | Name | PDU | Devices & Protocols |
|---|---|---|---|
| 7 | Application | Data | HTTP, FTP, SMTP, DNS, DHCP, SNMP |
| 6 | Presentation | Data | SSL/TLS, JPEG, ASCII, compression, encryption |
| 5 | Session | Data | NetBIOS, PPTP, RPC, session management |
| 4 | Transport | Segment | TCP (reliable), UDP (fast), port numbers |
| 3 | Network | Packet | Router, Layer 3 switch, IP, ICMP, ARP |
| 2 | Data Link | Frame | Switch, bridge, MAC address, Ethernet, VLANs |
| 1 | Physical | Bits | Hub, cables, connectors, repeaters, media converters |
OSI Model Quick Reference
The 7 Layers (Top to Bottom):
| Layer | Name | Function | Protocols/Devices |
|---|---|---|---|
| 7 | Application | User interface | HTTP, HTTPS, FTP, SMTP, DNS |
| 6 | Presentation | Data formatting | SSL/TLS, JPEG, GIF, MPEG |
| 5 | Session | Session management | NetBIOS, RPC, SQL |
| 4 | Transport | Reliable delivery | TCP, UDP |
| 3 | Network | Routing | IP, ICMP, Routers |
| 2 | Data Link | Frames | Ethernet, MAC, Switches |
| 1 | Physical | Bits | Cables, Hubs, NICs |
Memory Aid: "All People Seem To Need Data Processing" or "Please Do Not Throw Sausage Pizza Away" (bottom-up)
Key Points:
- Layers 1-4: Transport set (data flow)
- Layers 5-7: Application set (user interface)
- Routers operate at Layer 3
- Switches operate at Layer 2
- Hubs operate at Layer 1
Subnetting Quick Reference
Subnetting is one of the most challenging topics for Network+ candidates, but it is absolutely essential. The exam expects you to quickly calculate the number of usable hosts, identify network and broadcast addresses, and convert between CIDR notation and dotted decimal. The key formulas to memorize are: Hosts per subnet = 2^(host bits) - 2 and Number of subnets = 2^(borrowed bits). Practice these calculations until you can solve them in under 30 seconds each.
| CIDR | Subnet Mask | Usable Hosts | Block Size |
|---|---|---|---|
| /24 | 255.255.255.0 | 254 | 256 |
| /25 | 255.255.255.128 | 126 | 128 |
| /26 | 255.255.255.192 | 62 | 64 |
| /27 | 255.255.255.224 | 30 | 32 |
| /28 | 255.255.255.240 | 14 | 16 |
| /29 | 255.255.255.248 | 6 | 8 |
| /30 | 255.255.255.252 | 2 | 4 |
Private IP address ranges: Class A: 10.0.0.0 – 10.255.255.255 (/8). Class B: 172.16.0.0 – 172.31.255.255 (/12). Class C: 192.168.0.0 – 192.168.255.255 (/16). APIPA: 169.254.0.0/16 (assigned when DHCP fails). Loopback: 127.0.0.1. These ranges appear in almost every Network+ exam.
Subnetting Quick Reference
CIDR Quick Chart:
| CIDR | Subnet Mask | Hosts | Block Size |
|---|---|---|---|
| /24 | 255.255.255.0 | 254 | 256 |
| /25 | 255.255.255.128 | 126 | 128 |
| /26 | 255.255.255.192 | 62 | 64 |
| /27 | 255.255.255.224 | 30 | 32 |
| /28 | 255.255.255.240 | 14 | 16 |
| /29 | 255.255.255.248 | 6 | 8 |
| /30 | 255.255.255.252 | 2 | 4 |
Quick Formulas:
- Hosts = 2^(32-CIDR) - 2
- Subnets = 2^borrowed bits
Powers of 2: 2, 4, 8, 16, 32, 64, 128, 256
Private IP Ranges:
- 10.0.0.0/8 (Class A)
- 172.16.0.0/12 (Class B)
- 192.168.0.0/16 (Class C)
Special Addresses:
- 127.0.0.1: Loopback
- 169.254.x.x: APIPA
- 255.255.255.255: Broadcast
Essential Network Commands
The Network+ exam tests your knowledge of both Windows and Linux command-line networking utilities. You need to know the equivalent commands across both operating systems and understand when to use each tool in a troubleshooting scenario.
| Windows | Linux | Purpose |
|---|---|---|
ipconfig /all | ifconfig / ip addr | Display IP configuration, MAC, gateway, DNS |
ping | ping | Test connectivity and measure latency |
tracert | traceroute | Trace the path packets take to a destination |
nslookup | dig | Query DNS records for a domain |
netstat -an | ss -tuln | Show active connections and listening ports |
arp -a | arp -a | Display ARP cache (IP-to-MAC mappings) |
pathping | mtr | Combined ping + tracert with loss statistics |
nmap | nmap | Port scanning and network discovery |
Network Troubleshooting Commands
Essential Commands (Windows):
ipconfig - View/manage IP configuration
- `ipconfig /all` - Detailed info
- `ipconfig /release` - Release DHCP lease
- `ipconfig /renew` - Renew DHCP lease
- `ipconfig /flushdns` - Clear DNS cache
ping - Test connectivity
- `ping 8.8.8.8` - Test internet
- `ping -t` - Continuous ping
tracert - Trace route path
- Shows each hop to destination
- Identifies where packets fail
nslookup - DNS queries
- `nslookup domain.com` - Resolve name
- `nslookup -type=mx domain.com` - MX records
netstat - Network statistics
- `netstat -an` - All connections, numeric
- `netstat -b` - Show applications
arp - ARP table
- `arp -a` - Display ARP cache
Linux Equivalents:
- ifconfig / ip addr (for ipconfig)
- traceroute (for tracert)
- dig (alternative to nslookup)
Wireless Standards Quick Reference
The Network+ exam covers all major 802.11 wireless standards. You need to know the frequency bands, maximum theoretical speeds, and which standards are backward compatible with each other. Pay special attention to Wi-Fi 6 (802.11ax) as it is heavily featured on the current exam.
| Standard | Wi-Fi Name | Frequency | Max Speed |
|---|---|---|---|
| 802.11a | — | 5 GHz | 54 Mbps |
| 802.11b | — | 2.4 GHz | 11 Mbps |
| 802.11g | — | 2.4 GHz | 54 Mbps |
| 802.11n | Wi-Fi 4 | 2.4 / 5 GHz | 600 Mbps |
| 802.11ac | Wi-Fi 5 | 5 GHz | 6.9 Gbps |
| 802.11ax | Wi-Fi 6/6E | 2.4 / 5 / 6 GHz | 9.6 Gbps |
Wireless Standards
802.11 Standards:
| Standard | Frequency | Max Speed |
|---|---|---|
| 802.11a | 5 GHz | 54 Mbps |
| 802.11b | 2.4 GHz | 11 Mbps |
| 802.11g | 2.4 GHz | 54 Mbps |
| 802.11n | Both | 600 Mbps |
| 802.11ac | 5 GHz | 3.5 Gbps |
| 802.11ax | Both | 9.6 Gbps |
Wireless Security:
- WEP: Deprecated, insecure
- WPA: Improved, still weak
- WPA2: Current standard, AES
- WPA3: Latest, strongest
Channels:
- 2.4 GHz: Channels 1, 6, 11 (non-overlapping)
- 5 GHz: More channels, less interference
Wireless Terms:
- SSID: Network name
- BSSID: Access point MAC
- ESSID: Extended service set ID
Network Topologies and Cable Types
Understanding physical and logical network topologies is essential for the Network+ exam. You should know the characteristics, advantages, and disadvantages of each topology, as well as the cable types and their maximum distances.
- Star topology: Most common in modern networks. All devices connect to a central switch. Single point of failure is the switch
- Mesh topology: Every device connects to every other device. Full mesh provides maximum redundancy but is expensive
- Cat 5e: Up to 1 Gbps, 100 meters maximum distance
- Cat 6: Up to 10 Gbps at 55 meters, 1 Gbps at 100 meters
- Cat 6a: Up to 10 Gbps at 100 meters
- Single-mode fiber: Long distances (up to 100 km), uses laser, smaller core
- Multimode fiber: Shorter distances (up to 2 km), uses LED, larger core
Cable Types and Standards
Ethernet Cables:
| Type | Speed | Distance | Use |
|---|---|---|---|
| Cat5e | 1 Gbps | 100m | Legacy networks |
| Cat6 | 10 Gbps | 55m | Standard installations |
| Cat6a | 10 Gbps | 100m | Data centers |
| Cat7 | 10 Gbps | 100m | High interference |
Fiber Types:
- SMF (Single-mode): Long distance, expensive
- MMF (Multi-mode): Short distance, cheaper
Fiber Connectors:
- SC: Push-pull square
- LC: Small form factor
- ST: Bayonet twist-lock
- MTRJ: Small, duplex
Copper Connectors:
- RJ-45: Ethernet
- RJ-11: Phone/DSL
- F-type: Coaxial
Cable Standards:
- T568A and T568B: Different pin assignments
- Straight-through: Device to switch
- Crossover: Same device types
Test Your Network+ Knowledge
Put this cheat sheet to the test with realistic Network+ practice questions.
Start Free Practice Test →Facts and planning estimates
- OSI Layers
- 7
- Key Ports
- 25+
- Commands
- 12+
- Cable Types
- 8+
Study tips
Print this cheat sheet and review it during your final week of preparation.
Create flashcards for ports and protocols—they're heavily tested.
The OSI model appears in nearly every form of the exam—know it cold.
Practice subnetting until the calculations are automatic—no hesitation.
Know both Windows and Linux command variations for troubleshooting.
Common mistakes to avoid
Memorizing ports without understanding what each protocol does.
Confusing subnet mask with CIDR notation or wildcard mask.
Forgetting the differences between TCP and UDP protocols.
Not knowing both T568A and T568B wiring standards.
Mixing up single-mode and multi-mode fiber characteristics.
Study perspective
A cheat sheet is most valuable when you already understand the material—it's for quick recall, not learning. If anything on this sheet is unfamiliar, go back to your comprehensive resources before relying on quick reference.
Test Your Network+ Knowledge
See how well you know these concepts.
Frequently Asked Questions
What ports should I memorize for Network+?
Essential ports: FTP (20/21), SSH (22), Telnet (23), SMTP (25), DNS (53), DHCP (67/68), HTTP (80), HTTPS (443), POP3 (110), IMAP (143), SNMP (161/162), LDAP (389), RDP (3389), and NTP (123). Know both TCP and UDP designations for each.
What are the 7 OSI layers?
From bottom to top: Physical (Layer 1), Data Link (Layer 2), Network (Layer 3), Transport (Layer 4), Session (Layer 5), Presentation (Layer 6), Application (Layer 7). Remember with "Please Do Not Throw Sausage Pizza Away."
Do I need subnetting for Network+?
Yes. You need to calculate subnet masks, network addresses, broadcast addresses, usable hosts, and convert CIDR notation. Practice until you can solve subnetting problems in under 30 seconds. Write your subnetting table on the whiteboard as part of your brain dump.
Can I bring notes into the Network+ exam?
No. CompTIA exams do not allow any reference materials. However, you get a whiteboard or erasable notepad at the testing center. Many candidates do a brain dump of memorized information — ports, subnetting tables, OSI layers — onto this notepad immediately when the exam starts before answering any questions.
What networking commands should I know?
Key commands: ipconfig/ifconfig (IP configuration), ping (connectivity test), tracert/traceroute (path tracing), nslookup/dig (DNS lookup), netstat (connection stats), arp (ARP table), nmap (port scanning), pathping (combined ping+tracert). Know both Windows and Linux equivalents.
What wireless standards are tested on Network+?
You need to know 802.11a (5 GHz, 54 Mbps), 802.11b (2.4 GHz, 11 Mbps), 802.11g (2.4 GHz, 54 Mbps), 802.11n/Wi-Fi 4 (2.4/5 GHz, 600 Mbps), 802.11ac/Wi-Fi 5 (5 GHz, 6.9 Gbps), and 802.11ax/Wi-Fi 6 (2.4/5/6 GHz, 9.6 Gbps). Know frequencies, max speeds, and backward compatibility.
Can I use a cheat sheet during the Network+ exam?
No, you cannot bring any materials into the exam room. However, you'll have a whiteboard to write notes at the start. Many candidates write key formulas or ports before starting questions.
What should I memorize for Network+?
Prioritize: OSI model layers, common ports and protocols, subnetting calculations, troubleshooting commands, and cable types. These appear on every exam form.
How do I remember all the ports?
Group ports by function (email, web, file transfer, remote access). Create mnemonics or stories. Flashcards with daily review are most effective for long-term retention.
Is the OSI model really that important?
Yes, the OSI model is fundamental to Network+ and appears directly and indirectly in many questions. Understanding which protocols and devices operate at each layer is essential.
What subnetting should I know for Network+?
Know CIDR notation, subnet mask conversion, calculating hosts per subnet, identifying network/broadcast addresses, and VLSM concepts. Practice until calculations are automatic.
Are troubleshooting commands tested on Network+?
Yes, both in multiple-choice questions and performance-based questions. Know the purpose and output of ping, tracert, ipconfig, nslookup, netstat, and arp.
Practice & quick reference
- N+ Acronyms
- Fundamentals
- Free Practice Test
Test your knowledge · Getting started guide
- Free Network+ Practice Test
Check recall with real questions · Free practice test
Study tools & plans
- Study Guide
Complete preparation plan
- Exam Tips
Test-taking strategies
- Study Time
- 30-Day Plan
- Certification Overview
Complete guide and requirements
- How to Pass
Study tips and exam strategies
- Network+ Exam Objectives Explained
The blueprint behind the cheat sheet · Exam objectives
Exam facts & renewal
- Passing Score
- Is Network+ Hard? 2026 Difficulty Analysis
Difficulty
- Network+ Exam: Up to 90 Questions (2026)
How many questions
- Does Network+ Expire? 2026 Renewal Guide
Does it expire?
- Failed Network+? Retake Policy & Tips (2026)
If you fail
Career & comparisons
- Is Network+ Worth It in 2026? ROI Analysis
Worth it?
- Network+ Without Experience: 2026 Guide
Without experience