This is a quick and easy CCNA cheat sheet I created while studying.
It includes all the important things you need to remember—like port numbers, routing protocols, IP ranges, security basics, QoS markings, and more.
Everything is organized in clean tables so you can revise fast and cram before the exam.
If you're preparing for CCNA or just want a quick networking refresher, this guide will help you a lot.
Enjoy learning and happy studying!
| Protocol | Port | Type | Description |
|---|
| FTP (Data/Control) | 20 / 21 | TCP | File transfers |
| SSH | 22 | TCP | Secure remote login |
| Telnet | 23 | TCP | Insecure remote login |
| SMTP | 25 | TCP | Email sending |
| TACACS+ | 49 | TCP | AAA (Cisco) |
| DNS | 53 | UDP/TCP | Name resolution |
| DHCP | 67 / 68 | UDP | Dynamic IP allocation |
| TFTP | 69 | UDP | Simple file transfer |
| HTTP | 80 | TCP | Web traffic |
| POP3 | 110 | TCP | Email retrieval |
| NTP | 123 | UDP | Time synchronization |
| IMAP4 | 143 | TCP | Advanced mail retrieval |
| SNMP | 161 / 162 | UDP | Network monitoring |
| BGP | 179 | TCP | Exterior routing |
| LDAP | 389 | TCP | Directory services |
| HTTPS | 443 | TCP | Encrypted web |
| SYSLOG | 514 | UDP | System logging |
| RIP | 520 | UDP | Routing updates (IPv4) |
| RIPng | 521 | UDP | Routing updates (IPv6) |
| RADIUS | 1812 / 1813 | UDP | AAA (Auth/Acct) |
| HSRP | 1985 | UDP | Gateway redundancy |
| GLBP | 3222 | UDP | Load balancing gateway |
| CAPWAP | 5246 / 5247 | UDP | WLC to AP control/data |
| Puppet | 8140 | TCP | Puppet pull model |
| CHEF | 10002 | TCP | Chef push model |
- OSPF → 89
- EIGRP → 88
- VRRP → 112
- IPsec AH → 51
- IPsec ESP → 50
| Source | AD | Notes |
|---|
| Connected | 0 | Most trusted |
| Static | 1 | Manual route |
| EIGRP Summary | 5 | Auto-summary route |
| eBGP | 20 | External BGP |
| EIGRP Internal | 90 | Inside same AS |
| OSPF | 110 | Link-state IGP |
| IS-IS | 115 | Intermediate System |
| RIP | 120 | Distance vector |
| EIGRP External | 170 | Redistributed |
| iBGP | 200 | Internal BGP |
| Unknown | 255 | Never used |
| Standard | Description |
|---|
| 802.3 | Ethernet (LAN) |
| 802.1Q | VLAN trunk tagging |
| 802.1D | STP |
| 802.1w | Rapid STP |
| 802.1s | Multiple STP |
| 802.1X | Port-based access control |
| 802.1AB | LLDP |
| 802.3af/at/bt | PoE / PoE+ / UPOE |
| 802.11 a–ax | Wi-Fi standards |
| Protocol / Service | MAC Address |
|---|
| CDP | 01:00:0C:CC:CC:CC |
| LLDP | 01:80:C2:00:00:0E |
| STP | 01:80:C2:00:00:00 |
| PVST+ | 01:00:0C:CC:CC:CD |
| HSRPv1 | 0000.0C07.ACXX |
| HSRPv2 | 0000.0C9F.FXXX |
| VRRP | 0000.5E00.01XX |
| GLBP | 0007.B400.XXYY |
| IPv4 Multicast | 01:00:5E:00:00:XX |
| IPv6 Multicast | 33:33:XX:XX:XX:XX |
| Type | Range | Notes |
|---|
| Private A | 10.0.0.0/8 | |
| Private B | 172.16.0.0/12 | |
| Private C | 192.168.0.0/16 | |
| Loopback | 127.0.0.0/8 | Localhost |
| Link-local | 169.254.0.0/16 | APIPA |
| Multicast | 224.0.0.0/4 | Class D |
| Reserved | 240.0.0.0/4 | Class E |
| Broadcast | 255.255.255.255 | Local network |
| Type | Prefix | Notes |
|---|
| Unspecified | :: | No address |
| Loopback | ::1 | Localhost |
| Link-local | fe80::/10 | Non-routable |
| Unique Local | fc00::/7 (fd00::/8) | Private |
| Global Unicast | 2000::/3 | Public |
| Multicast | ff00::/8 | Group comms |
| Solicited Node | ff02::1:ffXX:XXXX | Used in ND |
| Protocol | Address |
|---|
| All Hosts | 224.0.0.1 |
| All Routers | 224.0.0.2 |
| OSPF All Routers | 224.0.0.5 |
| OSPF DR/BDR | 224.0.0.6 |
| RIPv2 | 224.0.0.9 |
| EIGRP | 224.0.0.10 |
| VRRP | 224.0.0.18 |
| IGMPv3 | 224.0.0.22 |
| HSRPv2 / GLBP | 224.0.0.102 |
| Protocol | Address |
|---|
| All Nodes | ff02::1 |
| All Routers | ff02::2 |
| OSPFv3 All | ff02::5 |
| OSPFv3 DR | ff02::6 |
| RIPng | ff02::9 |
| EIGRPv6 | ff02::A |
| DHCPv6 Agents | ff02::1:2 |
| Solicited Node | ff02::1:ffXX:XXXX |
| Term | Description |
|---|
| AAA | Authentication, Authorization, Accounting |
| RADIUS | UDP 1812/1813 – encrypts password only |
| TACACS+ | TCP 49 – encrypts full payload |
| PAP | Plaintext auth |
| CHAP | Encrypted handshake |
| 802.1X | Port-based NAC using RADIUS |
| IPsec | AH 51, ESP 50, IKE (UDP 500) |
| SSH | Secure CLI (TCP 22) |
| HTTPS | Secure web (TCP 443) |
| ACLs | Std (1–99), Ext (100–199) |
| NAT/PAT | IP translation (PAT = overload) |
| Feature | Details |
|---|
| Modes | Protect, Restrict, Shutdown |
| Sticky | Learns & saves MACs |
| Default | Shutdown on violation |
| Recovery | Manual (shut/no shut) or auto |
| Level | Name | Mnemonic |
|---|
| 0 | Emergency | Every |
| 1 | Alert | Awesome |
| 2 | Critical | Cisco |
| 3 | Error | Engineer |
| 4 | Warning | Will |
| 5 | Notice | Need |
| 6 | Informational | Icecream |
| 7 | Debug | Daily |
| Type | Encryption | Notes |
|---|
| WEP | RC4 | Insecure |
| WPA | TKIP | Obsolete |
| WPA2 | AES-CCMP | Secure |
| WPA3 | SAE | Most secure |
| WPA2-PSK | Shared key | |
| WPA2-Enterprise | 802.1X + RADIUS | Enterprise |
| Field | Bits | Example |
|---|
| CoS (802.1p) | 3 bits | L2 switch tagging |
| DSCP (L3) | 6 bits | EF = 46 (voice) |
| IP Precedence | 3 bits | Legacy |
| Type | Data Type | Example |
|---|
| Platinum | Voice | Voice traffic |
| Gold | Video | Video traffic |
| Silver | Standard | Web apps |
| Bronze | Best Effort | Basic traffic |
