Wha will happen if WAN is down? Case : Exchange Server DAG in two site configuration

Ardan Zaki 236 Reputation points

Hi Every one.

I have this question as it has been my concern for my Exchange server topology design.


What will happen to that system if the WAN is down which means DC cannot communicate with DRC.

Will all databases be active in both sites? or only active on DC? as two site is running normaly except for communication between two site


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  1. Andy David - MVP 145.1K Reputation points MVP

    The DC Site will remain up and running because the Witness Server is there.

    In your scenario, you have 4 in each DC and the witness server in the primary will give you quorum.

    the DRC will not have quorum with only 4 DAG members. the alternate witness server is not used unless you tell the DAG to use it as the FSW.

    See Datacenter switchovers:


    1 person found this answer helpful.