DNS config for Trust relationship

Hi,

I have 2 W2k domain in differents forest on the same phisical LAN, one server is the DHCP and DNS server for both domain.
The error i am getting when trying to set up the re trust is “cannont connect the other domain”.
At this poing i have very clear that it is a DNS server configuration problem. Can anyone tell me how to configure the zones in both DNS to be able to do the trust? I am just starting to work with DNSs.

Thanks