Can't look up local names

[Sir]

I am running FreeBSD4.1 stable with bind 9.1.0. I have configured
named.conf and all of the zone files associated with it. My problem was
a basic one but pointed out a knowledge gap. At first, I couldn't look
up names in the local domain i.e.;

nslookup warren

server : localhost
address : 127.0.0.1

**** localhost can't find warren : Non-existant host/domain


my "hostname" was set to "warren". When I set it to
warren.masspostroad.net the local lookups work fine. "domainname" still
returns "". I've read all I could, even bought "the" O'Reiley book and I
guess they assume you already know some things that I don't.  Does
anyone in the know have the time to front me some background into what's
going on here. I thought the zone file would suffice to explain to the
name server who it is and it's SOA?