With a dual site architecture with a VMware Cloud Provider, another benefit of Microsoft Exchange 2013 is that the namespace model can be simplified.

This sample solution architecture uses the Client Access Server to proxy requests to the mailbox server hosting the active database copy. This allows the CAS in one site, for instance the VMware Cloud Provider Program data center, to proxy a session to a mailbox server that is located in the on-premises data center. Assuming that network use, latency, and throughput are not a design concern, this allows us to employ a single namespace across both sites for redundancy, which also simplifies the namespace architecture.

For instance, in our sample design scenario where two data centers with low latency, throughput, and use between the on-premises and off-premises facilities exist, the design can simplify the namespace so that users only have to use a single namespace name for Internet access, regardless of where their mailbox is located. With the architecture shown in the following figure, the CASs in both data centers can be used to route and proxy traffic to the mailbox server hosting the user’s active database copy.

Because network traffic is not a concern in this architecture, for an optimal solution, DNS is configured to round-robin between the VIPs of the load balancers located in each data center. The result is that there is a site-resilient namespace design as long as you can accept that 50 percent of the client connections will be proxied from the alternate site.