Ok, here is the situation:
We have recently had a reverse lookup added to our ISPs DNS tables to correct a problem with having our e-mails on some servers rejected as spam, we now have a problem with our client machines accessing the exchange server, they now see the external lookup and not the DNS entry on our server. We have dhcp server running giving out our server as the first point of call and the ISPs DNS server as the second. How can this machine still be trying to access the external IP address of our ISA server?
when a machine first boots up or I renew the IP address the server is clearly visible on the internal IP address, however over time the machine is resolving the host name to the external IP address. Even the DNS server will not resolve the host to the internal IP address.
The problem clearly lies with the DNS server, but how the exchange server is clearly visible with the internal IP address in the forward lookup zone for our domain.