Ports between ISA and DC

[<sf_mail_sbm () yahoo com>]

Hi List,

I have the following config


                     
                 ____
INTERNET <------| FW |--------> Domain Controller (in LOCAL LAN)
                   |
                   |
                 -----
                  ISA (in DMZ)

ISA is doing Web Proxy only

Only users in a particular user group can access the web

Trying to find out the ports that ISA needs to talk with the DC for authentication of users instead of opening all 
ports on the Firewall

Could not find same from Microsoft site

If someone knows the ports that need to be opened, please share it with us

Thanks,
Ronish