We have an Exchange 2013 Environment running on Server 2012 R1.
We currently have two MBX Servers in a DAG, and only one CAS.
I want to add a second CAS for redundancy. The current CAS is on Cumulative Update 5.
Questions:
1. Can I install CAS2 with CU7 and add to Exchange, or do I need to update CAS1 to CU7 first?
2. When I upgrade CAS1 to CU7 - how much downtime will there be?