This is a frequently asked question. How do I stop IOS from querying DNS?

Often when we introduce a typo and the command does not exist, our router or switch will try to resolve the ip address using DNS. If it is not configured, it’s gonna take a long while on doing nothing at all.

If we type in klhsd and we enter, if we count will pass around 8 seconds, we are loosing a very precious time. If we are sitting the CCIE Lab, well, you know.

We have 2 possible solutions here:

  • no ip domain lookup: We stop the router to query abdolutely nothing using DNS. Watch out here!, we will not be able to ping www.google.com, let’s say, and we may need it.
  • transport preferred none: This command stops the router from running incorrect commands such as ping or sohw, even x.x.x.x without typing telnet or ssh before.

Please follow this advice, forget no ip domain lookup and use the second option. Cleaner.