Craig Hunt's book is a good overall reference geared for sysadmins.

"DNS and BIND" is *the* DNS book. It is very BIND oriented, but so is DNS. If you run a name server, get this book. Even if you don't run BIND, everyone else does.

Dan Bernstein has a BIND replacement, just like he has a Sendmail replacement (qmail). He has some interesting ideas about the "right" way to do DNS, and some of them are pretty good. Well worth a look. If you are thinking about setting up BIND, djbdns might be a better choice.