After many hours working with clients trying to resolve communication failures and sporadic problems, I felt it was about time I put together a matrix on port communication based on many common scenarios. I’ve run in to some very unusual problems with some of my clients and I found most of these problems stem from the High RPC ports being closed. Other unusual problems come from Global Catalog servers being blocked from the GC LDAP ports.
I’ve found that even client communication can be tricky if you have internal firewalls between your client machines and servers. However, as Exchange and the Outlook evolve, we’ve found easier ways to minimize so many port requirements. Now it’s a matter of getting every client to use RPC over HTTP.
I have posted a screenshot of the spreadsheet I have created to define port requirements. You can also obtain the attached spreadsheet for your use.
