Located at /etc/resolv.conf, this file defines your search domains and your DNS servers. You probably don't want more than 4 to 6 search domains and you cannot have more than three DNS servers listed. The format is:
domain freebsdwiki.net nameserver 169.254.1.1 nameserver 172.16.1.1
To attempt to resolve incompletely qualified hostnames using more than one domain name if necessary, use:
search freebsdwiki.net somethingelse.com anotherdomain.org
Be careful with this, you really don't want to have every attempt at a DNS resolution take 15 seconds or more to time out because you have to contact tons of different nameservers due to your "search" string.