Made a Typo? IOS Will Make You Wait for DNS Resolution

Another one of those Cisco IOS gotchas: when mistyping a command, you have to wait a minute before you get back a prompt. How to get back your prompt right away?

To beginners with fat fingers like me, this happens all the time:

Router> foo
Translating "foo"...domain server (255.255.255.255)

IOS interprets this as a hostname to Telnet into. It will make you wait a minute before you can continue:

If the router has no DNS servers configured, another IOS default causes the router to broadcast on the connected subnets looking for a DNS server to resolve names – with around a one-minute timeout waiting for a response.

Ctrl+C does nothing, but instead, we have to press Ctrl+^ to quickly cancel that command:

Router> foo
Translating "foo"...domain server (255.255.255.255) % Name lookup aborted

Type no ip domain-lookup in global configuration mode to disable all DNS lookups. I do not currently know if there are any downsides to this.