2003 domain trust and user authentication

[buktzn]

Hi

I have a 2003 active directory domain with 2 domain controllers on a vlaned subnet. We are setting up a user segment on a separate subnet which will be firewalled. I want to add another domain controller into this subnet. Now heres the question. If i want to setup an external trust to another forest, and have user authentication attempts forwarded to the external domain. Can you force all forwards to only occur from 1 domain controller(user segment)? This is due the the user segment being on a separate subnet, which will only have firewalled access to the external domain. The primary subnet wont have access.

Thanks
Mario