Privileged EXECDomain 3.0

show ip interface brief

Provides a condensed, single-line-per-interface status report. It is the primary tool for verifying interface connectivity, confirming IP address assignments, and identifying physical or logical failures across an entire chassis.

Quick Reference

Execution ModeRouter#

Privilege Level1 (User or Privileged)

ScopeGlobal (All Interfaces)

Primary Use"The first command to run when troubleshooting a connection."

Reading the Output

Interface IP-Address OK? Method Status Protocol

GigabitEthernet0/0 10.1.1.1 YES manual up up

GigabitEthernet0/1 unassigned YES unset administratively down down

Vlan1 192.168.1.1 YES manual up up

Status (Left-most "up"): Refers to the Layer 1 (Physical) state. If it says "down" or "administratively down", the physical link or the switch port configuration is the culprit.
Protocol (Right-most "up"): Refers to the Layer 2 (Data Link) state. If Status is "up" but Protocol is "down", you have a Layer 2 encapsulation mismatch (e.g., PPP/HDLC mismatch or keepalive failure).
Method: Displays how the IP was assigned (manual, DHCP, or NVRAM).

CCNA Exam Gotchas

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Status vs. Protocol: The Troubleshooting Key

The most frequent CCNA troubleshooting question involves an interface that is Up / Down. You must immediately identify this as a Layer 2 encapsulation mismatch. If it were a cable issue, the status would be Down / Down.