I have Exchange 2010 configured in (2) separate sites, each site with its own datacenter.
In each site, I have a DAG with (2) members, a CAS-Array with (2) members, and a hardware load balancer.
For the most part, I have users setup so that if they are in site 1, their mailbox is in the site 1 DAG. Likewise, if they are in site 2, their mailbox is in the site 2 DAG.
However ... we sometimes run into issues where a user is physicall located in site 1, but their mailbox is in site 2...in this instance, considering that the Exchange DAG properties tells the database that it's CAS-Array is set to be the CAS-Array in site 2, the user connects to the CAS server in site 2 (even though the user is physically located in site 1).
Is there any way to get the user to connect to the local CAS server in site 1 in order to use their mailbox in site 2? Is this even worth it? Does it make a difference for a user to connect to a local CAS server that will access a mailbox in a database that lives in another site?
I was also wondering ... if there was NOT an Exchange database in a physical site and all users in a remote site connected across a WAN link / VPN to access all Exchange resources in a main datacenter, but the remote site had physical infrastructure that COULD support a CAS server, would it help the site at all to have a local CAS that could take connections from Outlook and other desktop calls and send them to the database server at the main datacenter ... or is this a silly thought, and are things best left accessing them across a WAN link?