I am currently architecting an Exchange environment that consists of the following: One server running Microsoft Exchange 2010 Client Access/Hub Transport server roles and one server running the mailbox role that is connected to a fiber Storage Area Network (SAN). In the future I want to implement DAG. Can I use a server that runs all three of the roles (Sort of like SCR in Exchange 2007) for DAG or does it have to be just a mailbox role server with the Client Access and Hub Transport roles separate, running on a different server? Thanks in Advance. Larry

Hi You can have all roles on it, to use DAG you need Windows Enterprise because DAG uses Failover Clustering API's. I think you have read it but I tell you anyway, you can't combine DAG (Failover Clustering) and NLB.Jonas Andersson MCTS: Microsoft Exchange Server 2010, Configuration | MCITP: EMA | MCSE/MCSA Blog: http://www.testlabs.se/blog

Hi Jonas, Thank you for the quick reply! Larry

Yes, we cannot use DAG with NLB if Mailbox role is installed together with CAS role. If you want to achive the high availibility of CAS, they you can try to use Hardware Load balance. Regards, Xiu