Cisco "no shutdown" Command Explained
no shutdown — administratively enables an interface — router ports are shut by default, and this is the command that brings them alive. Runs in interface configuration mode.
Syntax and common variants
| Variant | Purpose |
|---|---|
no shutdown | Enable the interface |
shutdown | Administratively disable it |
show ip interface brief | Verify the resulting state |
Reading the output
| Output / element | Meaning |
|---|---|
%LINK-5-CHANGED: … changed state to up | Layer 1 came up |
%LINEPROTO-5-UPDOWN: … changed state to up | Layer 2 came up — fully operational |
administratively down (in show output) | Something/someone issued shutdown |
When to use it
The most common "why is nothing working" fix on new router configs — interfaces ship disabled. Equally, shutdown is your safety tool: disabling unused ports (security) or intentionally isolating a device during troubleshooting. Browse more in the command reference or practise in the free labs.
Frequently asked questions
Why is my new router interface down?
Router interfaces default to administratively down — configure the IP, then no shutdown.
Interface still down after no shutdown — why?
Now it's physical: cable seated, far end enabled, right port? Status down (not admin-down) means L1, not config.
Should unused switch ports be shut?
Yes — standard hardening: shutdown unused ports and park them in an unused VLAN.
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