You are integrating a new video endpoint with Cisco VCS, but you find that the unit is failing to register. You assign extension 4000 to the device in the "vc.ciscoexam.online" SIP domain, and you set its registration proxy to the IP address of 10.1.1.10 as the Cisco VCS. In order for the device to register via SIP, which format must you use when you set the SIP address of the device?

A.	4000@vc.ciscoexam.online
B.	4000
C.	4000@10.1.110
D.	4000@ciscoexam