Cisco UCM DNS Configuration

B.

DNS (Domain Name System) is an important component of a fully functional Cisco Unified Communications Manager (UCM) system. The DNS service is responsible for translating fully qualified domain names (FQDNs) into IP addresses that can be used by various components of the system.

The correct answer to this question is B. trunk.

Trunks are connections between two different systems or networks that are used for transporting voice, video, and data. These trunks can be either IP-based or circuit-based. In either case, the DNS service is used to resolve the FQDNs of the trunks into IP addresses that can be used for communication between the two systems or networks.

Option A, MRA (Mobile Remote Access), is incorrect because MRA is a feature that allows remote workers to securely access the corporate network using their mobile devices. While DNS can be used in this context, it is not required for the functionality of MRA.

Option C, AAR (Automated Alternate Routing), is also incorrect because AAR is a feature that allows for automatic rerouting of calls in case of congestion or unavailability of a particular route. While DNS can be used in this context, it is not required for the functionality of AAR.

Option D, H.323, is also incorrect because H.323 is a protocol used for audio and video conferencing over IP networks. While DNS can be used in this context, it is not required for the functionality of H.323.

In conclusion, DNS is an essential component of a fully functional Cisco UCM system. It is primarily used to resolve FQDNs to IP addresses for trunks that enable communication between different systems or networks.