/etc/hosts on UNIX box

If you are having a problem resolving hosts on a UNIX box even when you do have a /etc/hosts file configured with the hosts which are not there on the DNS server, check to make sure that you have a /etc/nsswitch.conf file. I know that by default a few UNIX systems like HP-UX do have it as a sample file but are renamed to something else. A ls -al nsswitch* will get you a list of all files which start with nsswitch. Copy one of them to /etc/nsswitch.conf and edit the line which starts with hosts:

hosts:         files [NOTFOUND=continue UNAVAIL=continue TRYAGAIN=continue] dns

This will ensure that your hosts will be resolved first by looking into /etc/hosts and if not found there the DNS server will be used. This can be very useful in the even the DNS server crashes or is unavailable for any reason.