DNS and all that stuff

Hi I've just rebuilt our main FS using Suse 8.1 following a complete hard drive failure (and no we didn't have a full backup). I've never been sure about the settings to use for host name, domain name, name servers and domain search list. Everything has always worked but we sometimes get poor performance which may be related to DNS queries. Many years back we called our domain derbymoor (school name) and the server derby. However, since we are now connected to broadband and our local machines can find out about the big wide world I wondered if we should use our official domain of derbymoor.derby.sch.uk. Should we be running a name server ie nscd or named? Any advice? Dave Williams