Isn't DNS a major part of AD? And when u say obtain automatically from DNS, I'm assuming you mean DHCP?

So you're having problems authenticating on a machine when u use a DHCP obtained address and no problems when u use a static? I'm assuming you're using the static address of the A record you have in DNS for it? Are you using DDNS (VM updates DNS when it gets an address? Check ur tcp/ip settings).