I have two Exchange 2010 servers in a DAG and a witness server to implement mailbox resiliency. The two Exchange servers are in two subnets and the Windows failover cluster therefore has two IP address resources.

I now that Exchange uses "core functionality" of Windows Server failover clustering, but it does not use all features. My setup also seems to work, but if I run the validation in the Windows Failover Cluster Manager, it complains about one of the IP address resources being offline. However, I cannot bring this resource online, because the server complains that "the specified cluster node is not the owner of the resource, or the node is not a possible owner of the resource". If I "Simulate failure of this resource", it becomes offline and the other IP becomes online.

I have the vague idea that Exchange might use the state of the IP resource to identify the Primary Active Manager, but I am not sure. As it is obviously important that failover really works, I would like to be sure. Therefore, my question is:

Is it normal that only one IP address resource in a Exchange 2010 DAG failover cluster is active at a time?

If not, how do I bring both resources online at the same time given the error described above?