[Samba] Understaning Domain Name Resolution

[Kevin B]

Hello,

I've read chapter 4 [and all other chapters btw] of the Samba by Example
latest version online and the mailing list archives
and have a question re: domain name resolution.

If I have a domain 'AD.NET' I can setup a zone in Bind with an SRV record
and my XP Pro clients can find the domain controller and join the domain.
A simple zone looks like this:

$ttl 38400
ad.net. IN      SOA     ad.ad.net. admin.ad.net. (
                       1113970738
                       10800
                       3600
                       604800
                       38400 )
ad.net. IN      NS      ad.ad.net.
ad.ad.net.      IN      A       192.168.4.3
_ldap._tcp.dc._msdcs.ad     IN    SRV  ad.ad.net

Now if my domain name happens to be 'AD' instead of 'AD.NET',
I have problems when joining the domain, XP Pro reports it cannot find 
the SRV record.  I tried defining domain 'AD' in dhcp scope instead of DNS
[per chapter 4] and tried running the Samba server as a WINS server and
pointing XP to it.
XP and the Samba DC are registering in wins.dat -but-
it still fails looking for an SRV record. Ethereal shows XP asking the
whole lan for the DC via DNS and no one knows it.

So I setup a master zone in bind for 'AD'[removing '.net' from each 
relevent line] above but still the DC cannot be found.

I'm sure a lot of old NT4 domains were single name so I'm hoping someone has
resolved this before.
Any pointers are greatly appreciated.

Thanks in advance.
Kevin