Which three statements are true about the voice VLAN feature on a Catalyst 2950 switch？ （Choose  three.）（）  

多项选择题WhichthreeWLANstatementsaretrue？（Choosethree.）（）

A. A lightweight AP receives control and configuration from a WLAN controller to which it is associated.
B. A WLAN client that is operating in half-duplex mode will delay all clients in that WLAN
C. A dhoc mode allows mobile clients to connect directly without an intermediate AP
D. Another term for infrastructure mode is independent service set （IBSS）
E. The Aironet 1230 access point is an example of an access point that operates solely as a lightweight  access point.
F. WLANs are designed to share the medium and can easily handle an increased demand of channel  contention.

单项选择题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. Effectively the trust boundary has been moved to the IP phone.
B. The host is now establishing the CoS value and has effectively become the trust boundary. 
C. The switch is rewriting packets it receives from the IP phone and determining the CoS value.  
D. The switch will no longer tag incoming voice packets and will trust the distribution layer switch to set theCoS
E. RTP will be used to negotiate a CoS value based upon bandwidth utilization on the link.

单项选择题Refer to the exhibit. Which statement is true about a voice VLAN？（）

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.

多项选择题Whichtwomulticastprotocolstatementsaretrue？（Choosetwo.）（）

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.

多项选择题WhichthreeIPmulticastgroupconceptsaretrue？（Choosethree.）（）

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.