免费下载 642-812认证考题 Demo

题库数目 : 227 Q&As             更新时间: 2010-1-12

Exam : Cisco 642-812
Title : BCMSN - Building Converged Cisco Multilayer Switched Networks

1. Which statement about the Lightweight Access Point Protocol (LWAPP) is true?
A. LWAPP encrypts control traffic between the AP and the controller.
B. LWAPP encrypts user traffic with a x.509 certificate using AES-CCMP.
C. LWAPP encrypts both control traffic and user data.
D. When set to Layer 3, LWAPP uses a proprietary protocol to communicate with the Cisco Aironet APs.
Answer: A

2. Which statement is true about IP telephony calls?
A. A Voice over IP (VoIP) packet consists of the voice payload, IP header, TCP header, RTP header, and Layer 2 link header.
B. The voice carrier stream uses H.323 to set up, maintain, and tear down call endpoints.
C. Call control signaling uses Real-Time Transport Protocol (RTP) packets that contain actual voice samples.
D. The sum of bandwidth necessary for each major application, including voice, video, and data, should not exceed 75 percent of the total available bandwidth for each link.
Answer: D

3. Refer to the exhibit. What is the effect when the switchport priority extend cos 3 command is configured on the switch port interface connected to the IP phone?
A. Effectively, the trust boundary has been moved to the PC attached to the IP phone.
B. The computer is now establishing the CoS value and has effectively become the trust boundary.
C. The IP phone is enabled to override with a CoS value of 3 the existing CoS marking of the PC attached to the IP phone.
D. The switch will no longer tag incoming voice packets and will extend the trust boundary to the distribution layer switch.
E. RTP will be used to negotiate a CoS value based upon bandwidth utilization on the link.
Answer: C

4. 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 the CoS.
E. RTP will be used to negotiate a CoS value based upon bandwidth utilization on the link.
Answer: A

5. Which three WLAN statements are true? (Choose three.)
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. Ad hoc 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.
Answer: ABC
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