If there is a need to use Microsoft Lync Server in the environment along with Exchange and CMN then pointing Autodiscover to the CMN Server breaks Lync for the rest of the environment.
This is caused by the Lync Server needing to be able to query the Autodiscover services hosted on the Exchange server.
The resolution is to do the following:
In a single name space scenario it is best to point Autodiscover to Exchange server running Autodiscover services normally in the Exchange environment.
