Thanks Pavan. I was more specifically looking to see what state this puts the Cisco Dead Server detection mechanisms in. So I labbed it up.
Depending on IBNS 1.0 vs 2.0 will change the available options for authentication failures. Basically, it can mark the server as Down if detecting that clearpass fails to respond to a radius authentication. However, detection mechanisms such as the automated-tester functionality will not work.
There is no change in the CPPM Radius serives if backend AD has become unreachable.