Which configuration concept allows for high-availability on IM and Presence services in a UC environment?

Refer to the exhibit.

What is a possible cause of the PRI issue?

Refer to the exhibit.

Endpoint A calls endpoint B.
What is the only audio codec that can be used for the call?

An incoming off-net call to a user fails. An engineer notices that the off-net call is G.711, but the phone accepts only G.729. Which media resource on a Cisco Unified Border Element and Cisco Unified Communications Manager must the engineer configure to manage the codec negotiation?

Refer to the exhibit.

A collaboration engineer needs to replace the original, single NTP server that was configured during the initial install of a Cisco UCM server What is the first step to accomplish this task?