The resolver is responsible for relaying DNS information to client programs. Configuring your resolver is a vital part of system administration. Even a DNS server needs a configured resolver, because the computer won't know it's a nameserver unless you tell it. Just about anything you do on a network requires a working name service client. Configuring a resolver involves answering a few questions:
Where does the server look for DNS information?
What are the local domain names?
Which nameservers should be queried?
The answers to these questions are configured in /etc/nsswitch.conf and /etc/resolv.conf.
This should be easy; a server gets its host information from a nameserver, right? I mean, that's ...