Refer to the exhibit. An engineer runs the utils diagnose test CLI command on a Cisco UCM subscriber and receives an error message during the validate_network test. What are two causes of the error?…

Missing PTR (Pointer) records for the Cisco UCM servers on the DNS server will cause a `validate_network` error because Cisco UCM performs reverse DNS lookups, and the absence of these records indicates an incomplete or incorrect DNS configuration.

A failure is not expected when `utils diagnose test` runs on a subscriber; the command is designed to confirm the healthy operation of all cluster nodes.

Having multiple PTR records for a single IP address of a Cisco UCM server is an an invalid DNS configuration that can lead to ambiguous name resolution and will be flagged as an error during the `validate_network` test.

While unreachable DNS servers would cause network validation to fail, this cause is often a result of underlying connectivity issues like a firewall blocking traffic (E), and A and C represent specific DNS record misconfigurations that are distinct causes.

A firewall blocking UDP port 53 would prevent DNS queries, making DNS servers unreachable (D), but A and C refer to specific DNS record integrity issues that can exist even if DNS servers are reachable.