Reauthentication on outlook


  • We have two servers in our CAS, load balanced by a hardware barracuda in single arm route-path mode. is the address to the HLB is the address to Exchange1 is the address to Exchange2

    Both Exchange1 and Exchange2 also have all of the other roles installed: hub transport and DAG.

    Occasionally when a client disconnects from the network and reconnects, or a database switch over occurs, clients are prompted by Outlook to reauthenticate.

    I did a packet capture on my PC and disconnected my NIC, waited for outlook to disconnect, then plugged it back in to see what happens when it asks for my password.  I have noticed a DCE/RPC packet from with's address in the packet data.  I then looked at netstat and noticed my PC is connected to both .2 and .3.  Since the HLB is configured to do TCP Proxying with L7 SSL offloading, I thought that all communications between clients and the exchange servers were supposed to terminate at the HLB, and the HLB would create a backend unencrypted connection to one of the CAS servers.

    What is going on here?

    Tuesday, February 28, 2012 5:51 PM