Multiple Roles Load Balancing in Exchange 2010
Need to deploy Exchange 2010 with all roles HUB, CAS and Mailbox to be load balanced. Currently deploying DAG with two members.
Suggestion to deploy all roles redundancy:
To load balance CAS you need to use Windows Network load balancing or Hardware load balancer. If you are also deploying DAG along with load balance CAS then it is recommended to install mailbox and CAS server role on different machines or servers. Because DAG uses Windows Failover Clustering which cant co-exist with Network Load balancer Or you can use Hardware Load balancer.
You could refer below article for regarding Load balancing in Exchange 2010
Understanding Load Balancing in Exchange 2010 http://technet.microsoft.com/en-gb/library/ff625247(v=exchg.141).aspx#options