What is one of the features of deploying Cisco Unified Communications Manager servers in a 1:1
redundancy design?

A.
When the primary servers approach 100% utilization, the backup servers can take over a
portion of the load

B.
If a single primary server fails, multiple servers can distribute the load generated by users
reregistering from the failed server.

C.
If multiple servers fail concurrently, the resulting load generated by users reregistering does not
overwhelm the dedicated backup servers due to 1:1 redundancy.

D.
Recovery happens faster when the load generated by the users from a failed server is spread
over more than one backup server

Explanation:
Link : http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/8x/callpros.html#wp1151374
Cisco Unified Communications System Release 8.x SRND , page- 283.
Explanation : One to one (1:1) — For every primary call processing subscriber, there is a
secondary or backup call processing subscriber.