/etc/resolv.conf

1. domain mydomain.com
2. nameserver 192.168.222.2
3. nameserver 192.168.222.3

You actually don't need this file to have your machine be a nameserver, but you'll need it if you want to do any lookups.

1. The domain that this machine is in is mydomain.com, so if you do a lookup on just sevilla without the mydomain.com, it will assume you mean sevilla.mydomain.com. (If you want to expand on this, investigate the search directive.)
2-3. The IP addresses of the name servers to use. Change 192.168.222.2 and 192.168.222.3 to whatever you want to use for your nameservers. This list can be as long as you want. The machines have to be running named...