Refer to the exhibit. What is the effect on the trust boundary of configuring the command mls qos trust  cos on the switch port that is connected to the IP phone？（）

A. Physically the voice network and the data network are separate.
B. The voice traffic will normally be on a different IP subnet than will the data traffic.
C. End user intervention is necessary to place the phone into the proper VLAN.
D. The same security policy should be implemented for both voice and data traffic.
E. The data VLAN must be configured as the native VLAN.

A. Dense mode multicast requires explicit join messages from their members.
B. Dense mode multicast uses a push model to flood traffic throughout the network and then prunes the  unwanted traffic.
C. Sparse mode multicast uses a pull model to send multicast traffic to where it is requested.  
D. Sparse mode uses reverse path forwarding （RPF） to prune off redundant flows.
E. The primary use of sparse mode multicast is for test labs and router performance testing.

A. If a packet is sent to a multicast group address， all members of the multicast group will receive it
B. If a packet is sent to a multicast group address， the multicast frame contains the source multicast  address
C. A router does not have to be a member of a multicast group to receive multicast data.
D. A router does not have to be a member of a multicast group to send to the group.
E. A router must be a member of a multicast group to receive multicast data.
F. A router must be a member of a multicast group to send to the group.