I configure the network connection with the following for all domains.
Each domain has a DNS server, which hosts its own DNS domain and other two DNS domains (secondary type).
As shown above, the trust type is an important concept. Because I raised both Contoso.com and VAN.COM to Forest Functional Level, I can have the forest-wide trust type established.I made mistake when I was establishing the trust between VANSTUDENTS.COM and VAN.COM. From VAN.COM, I create a Forest-wide type. From VANSTUDENTS.COM, the only choice is the EXTERNAL. The trust cannot be verified. Both sides must use the same TRUST TYPE. The only one between a Windows 2000 forest and Windows 2003 forest is the EXTERNAL.
