It doesn’t know my name or what command I am trying to type, so it tries to resolve this through DNS. This is really annoying for two reasons: first, because it doesn’t know my name, and second, because I need to hang out and wait for the name lookup to time out. You can get around this and prevent a time-consuming DNS lookup by using the no ip domain-lookup command on your router from global configuration mode.
If you have a DNS server on your network, you need to add a few commands to make DNS name resolution work:
• The first command is ip domain-lookup, which is turned on by default. It needs to be entered only if you previously turned it off (with the no ip domain-lookup command). The command can be used without the hyphen as well (ip domain lookup).
• The second command is ip name-server. This sets the IP address of the DNS server. You can enter the IP addresses of up to six servers.
• The last command is ip domain-name. Although this command is optional, it really should be set. It appends the domain name to the hostname you type in. Since DNS uses a FQDN system, you must have a full DNS name, in the form domain.com.