Configuration of DNS is required to achieve a fully functional Cisco UCM system Cisco UCM uses DNS to resolve fully qualified domain names to IP addresses for which destinations?

While application servers might use FQDNs, CUCM typically connects to them via IP address for internal services, and their FQDN resolution is not the primary use case for UCM's internal DNS resolution.

The primary TFTP server address is typically provisioned directly via DHCP Option 150 (IP address) or configured manually, and its FQDN is not primarily resolved by CUCM itself for its own operation.

The Cisco Unified Communications Manager Name is an internal identifier and does not typically require DNS resolution by the CUCM system itself to operate; CUCM nodes within a cluster communicate using IP addresses.

Cisco UCM frequently uses DNS to resolve FQDNs for SIP trunks. When configuring a SIP trunk to communicate with an external SIP gateway, session border controller (SBC), or another Unified CM cluster, the destination is often specified as an FQDN, which CUCM resolves via DNS to an IP address for call routing.