On a Cisco switch, which protocol determines if an attached VoIP phone is from Cisco or from
another vendor?

A.
RTP

B.
TCP

C.
CDP

D.
UDP

Explanation:
The Cisco Unified IP Phone uses CDP to communicate information such as auxiliary VLAN ID, per
port power management details, and Quality of Service (QoS) configuration information with the
Cisco Catalyst switch.