We are running Exchange 2010 SP2, 2 CAS servers w Client Access;Hub Transport roles installed; 2 Mailbox servers. Currently have DAG implemented for Database failover. I would like to setup a CAS Array for failover. I'm confused with the Network Load Balancer role, as I've seen various articles in how to set it up. I'm getting questioned why we need the Network Load Balancer, if the CAS array can basically fail over the client connection. I've would like to understand the benefits of setting up a NLB in addition to the CAS array.