A network administrator uses autoregistration to register IP phones to Cisco Unified Communications Manager. Later, the administrator changes the DNof the autoregistered phone to free the DN in the autoregisteration range. After a certain amount of time, the phones fail to autoregister, displaying “Error DB Config” or a similar message on the IP Phone screen. What is the root cause of this issue?
A. The network is down.
B. Cisco Unified Communications Manager server is down.
C. The phone is faulty.
D. The DNs are marked as unassigned.
