I have a domain with a windows DNS that works great for every computer in that subnet. Today I setup a remote office and joined them to the network through a VPN tunnel and so those computers are on another subnet. I then set the remote office to use the main office DNS and it works great for almost everything.
My only problem is that i cannot query for servers in the main office without having to add the full domain suffix;
nslookup dcserver.example.com <-- Works
nslookup dcserver <-- Doesn't work