This command allows the router to assume that any non-keyword entered in the command console is supposed to be resolved into an IP address. This is a default command.
Most people disable this command as it can be a frequent annoyance to those who mistype words on a regular basis.
In this example command that doesn’t exist is accidentally typed in. The router attempts to resolve this unrecognized command as an ip address, and takes awhile to do so. We disable this feature afterwards with no ip domain-lookup.
R2#wrong_command Translating “wrong_command”…domain server (255.255.255.255) (255.255.255.255) Translating “wrong_command”…domain server (255.255.255.255) % Unknown command or computer name, or unable to find computer address R2#conf t Enter configuration commands, one per line. End with CNTL/Z. R2(config)#no ip domain-lookup R2(config)#exit R2#wrong_command *Mar 1 02:13:07.747: %SYS-5-CONFIG_I: Configured from console by console R2#wrong_command Translating “wrong_command” % Unknown command or computer name, or unable to find computer address R2#