I’m facing the same problem in my SBS 2003 which is act as follows:
1. Directory Services
5. ISA 2004
After installing the ISA 2004 SP2, which is by default is blocking everything. What i want is the users to be able to Regest for an IP Address via the DHCP Services and get a Reply as well as for the DNS to resolve the names resolutions.
I have added the Rules which are recommened by Microsoft into the Firewall Rules for the DHCP, Restart the Firewall Services but still it won;t work.
Also, I have moved these two rules into the top of all the rules that i have in the Firewall Rules.