When you enter the interface command auto qos voip cisco-phone on a port at the edge of a network, how does the Cisco Catalyst switch detect if a Cisco IP Phone is connected to the port? （）A. by snooping the CoS marking on the incoming framesB. by using RTP hello messages between the switch port and the Cisco IP PhoneC. by using CDPD. by using DHCP snoopingE. by snooping the incoming 802.1Q VLAN tag

单项选择题

When you enter the interface command auto qos voip cisco-phone on a port at the edge of a network, how does the Cisco Catalyst switch detect if a Cisco IP Phone is connected to the port? （）

A. by snooping the CoS marking on the incoming frames
B. by using RTP hello messages between the switch port and the Cisco IP Phone
C. by using CDP
D. by using DHCP snooping
E. by snooping the incoming 802.1Q VLAN tag

CCNP(642-067)