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.
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.
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 |
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 |
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.
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 |
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 |
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.
Put this cheat sheet to the test with realistic Network+ practice questions.
Start Free Practice Test →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.
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."
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.
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.
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.
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.