DNS, can't get to sub-domain

[TechJones]

Hi all,
we have wind2k domain running AD. all of the clients look to the internal DNS server to resolve and the internal DNS has forwarders set up for external addresses.

our internal domain name (e.g. ourdomain.com) is the same as our external website domain name. when trying to resolve our external website name (e.g. "ping

http://www.ourdomain.com")the

DNS server was looking at the local domain and not the Website.
We got around this by adding a new host of

http://WWW and

gave it the IP address of our Website.
the
We have access to a subdomain on the website for testing purposes. (e.g. subdomain.ourdomain.com)

We cannot ping or connect to this domain wilst the client is looking at the internal DNS but it works if we change the client to look at an external DNS (one of the forwarders)
for AD to work properly we need to keep the clients pointed at the internal DNS
does anyone know what the problem is or know of a way around this.
Thanks
Gary.