CCNA 200-301 v1.1 quick lookup
Protocol numbers and ports
IP protocol numbers and the TCP/UDP port numbers used across the blueprint, with the services that own them.
Protocol numbers and portsIPv4 masks and block sizesIPv6 address spaceRouting codes and administrative distancesSyslog levels and thresholdsProtocol defaults and timers
From TCP and UDP — the same block lives in that article
Common IP protocol numbers
| Protocol number | Protocol | Notes |
|---|---|---|
| 1 | ICMP | Ping, errors, path discovery |
| 2 | IGMP | Multicast group membership |
| 6 | TCP | Reliable stream transport |
| 17 | UDP | Lightweight datagram transport |
| 50 | ESP | IPsec encapsulated security payload |
| 51 | AH | IPsec authentication header |
| 88 | EIGRP | Cisco interior routing protocol |
| 89 | OSPF | Link-state routing protocol |
Protocol numbers live in the IP header and name the upper-layer protocol — they are not TCP/UDP ports.
From TCP and UDP — the same block lives in that article
Well-known TCP ports
| Port | Service | Purpose |
|---|---|---|
| 20 | FTP data | Active-mode data channel |
| 21 | FTP control | Commands and replies |
| 22 | SSH | Secure remote access and SFTP |
| 23 | Telnet | Insecure remote access |
| 25 | SMTP | Mail transfer |
| 53 | DNS | Zone transfers and large responses |
| 80 | HTTP | Unencrypted web |
| 110 | POP3 | Mail retrieval |
| 143 | IMAP | Mail access |
| 443 | HTTPS | Encrypted web |
| 179 | BGP | Inter-AS routing (context) |
From TCP and UDP — the same block lives in that article
Well-known UDP ports
| Port | Service | Purpose |
|---|---|---|
| 53 | DNS | Standard name queries |
| 67/68 | DHCP | Server / client |
| 69 | TFTP | Trivial file transfer |
| 123 | NTP | Time synchronization |
| 161 | SNMP | Agent polling |
| 162 | SNMP traps | Manager receives notifications |
| 514 | Syslog | Log forwarding |
| 520 | RIP | Routing updates (context) |
| 1812/1813 | RADIUS | Authentication / accounting |
| 500 | IKE | IPsec key exchange |