Quiz Entry - updated: 2026.07.14
What does the show ip interface brief output tell you on a router, and what indicates a problem?
It lists every interface with its IP (Internet Protocol) address, OK?, method, Status and Protocol; anything other than up/up flags a problem — e.g. administratively down (forgot no shutdown) or unassigned (no IP set).
R1# show ip interface brief
Interface IP-Address OK? Method Status Protocol
GigabitEthernet0/0/0 192.168.10.1 YES manual up up
GigabitEthernet0/0/1 192.168.11.1 YES manual up up
Serial0/1/0 209.165.200.225 YES manual up up
Serial0/1/1 unassigned YES unset administratively down down
Reading the output:
| Status | Protocol | Meaning |
|---|---|---|
| up | up | Interface is fully operational |
| administratively down | down | shutdown command was used (or default for routers) |
| up | down | Physical link OK but Layer 2 protocol issue |
| down | down | No physical connection or remote end is down |
"unassigned" IP address means no IP has been configured — the interface needs configuration before it can route traffic.
Tip: If you see "administratively down" on a router interface you just configured, you probably forgot no shutdown.