I can ping the Exchange server here at work, but Outlook doesn't connect to it. I've verified the server is indeed the Exchange server and I've tried using the IP instead of the server name. I am also able to connect to port 135 using telnet (although nothing useful happens). I also tried running a trace using Wireshark but the protocols Outlook uses are proprietary and I couldn't see anything useful in the trace.
I'd love to hear some other steps I could take to track down the problem.
Best Answer
In our case the problem was with one of the routers along the way whose MTU was set to a low value. The packets sent by the RPC protocol were getting split and that for some reason prevented Outlook from working properly.
To determine the largest packet size that can get to the server, use the following command:
Replace 1500 with different values to determine the maximum size of the packet. After you know the value, use the instructions here to set the MTU size for your network connection.