Which CUCM database replication Issue would cause CUCM nodes to generate the error "Reverse DNS lookup failed"?

A.	DNS server is down
B.	DNS server reported that no IP address was returned for a requested A record lookup
C.	DNS server reported that no HOSTNAME was returned for a requested A record lookup
D.	DNS server reported that no IP address existed for a requested SRV record lookup
E.	DNS server reported that no HOSTNAME was returned for a requested PTR record lookup