CCIP 642-642 QoS Real Exam Questions

*The QoS exam will continue to be available for earning the other associated certifications after February 28, 2011.

The QoS exam is one of the qualifying exams for the CCIP, CCNP Voice, Cisco IP Telephony Design Specialist, Cisco IP Telephony Express Specialist, Cisco IP Telephony Operations Specialist, and Cisco IP Telephony Support Specialist certifications. The QoS 642-642 exam will test materials covered under the  Implementing Cisco Quality of Service QoS v2.3 course. The exam will certify  that the successful candidate has knowledge and skills necessary to configure  and troubleshoot Cisco IOS routers running Quality of Service protocols in  Service Provider and Enterprise environments. The exam covers topics on IP QoS, classification and marking Mechanisms, queuing mechanisms, traffic shaping and policing mechanisms, congestion avoidance mechanisms, link efficiency mechanisms, modular QoS command line interface, and QoS Best Practices.

1: In an unmanaged CE router implementation, how does the service provider enforce the SLA? using class-based policing on the CE to PE link to limit the customer’s input rate marking on the CE to PE link and using CBWFQ and CB-WRED on the PE to P link marking on the CE to PE link and using class-based policing on the PE to P link using class-based random discard on the CE to PE link to limit the customer’s input rate
Correct Answers: A

2: In a typical converged campus network, which two of the following are considered QoS best practices? (Choose two.)
A.Traffic classification and marking is performed as close to the traffic source as possible.
B.Traffic classification and marking is performed at the high speed core layer.
C.Ensure voice traffic is serviced by a weighted fair queue.
D.Only a reasonable number of applications should be classified into the mission-critical traffic class.
E.NBAR is used at the high speed core layer to discover and classify network applications.
F.Catalyst switches should use weighted round robin (WRR) queuing giving the voice traffic the highest priority.
Correct Answers: A D

3: What are two benefits of WFQ? (Choose two.)
A.WFQ is very easy to configure, and no manual traffic classification is necessary.
B.WFQ can provide fixed-bandwidth and fixed-delay guarantees.
C.WFQ can provide fixed-bandwidth guarantees.
D.WFQ can provide fixed-delay guarantees.
E.WFQ prevents the large-volume flows with large packet size from starving out the low-volume flows with small packet size.
F.Based on DSCP, WFQ allows weighted, random dropping of packets when the WFQ system is full.
Correct Answers: A E

4: Which technology is required when configuring FRF.12 on a Cisco device?
D.MLP with interleaving
Correct Answers: E

5: The following commands have been configured under the fa0/1 interface on the 2950 switch:
wrr-queue bandwidth 20 1 80 0
mls qos trust cos
mls qos trust device cisco-phone
Voice traffic from the IP phone that is directly connected to the fa0/1 interface is experiencing excessive delays. What could be the cause of this problem?
A.The wrr-queue bandwidth weightings are not correct.
B.The default wrr-queue cos-map is being used.
C.The default cos-to-dscp map is being used.
D.The default dscp-to-cos map is being used.
E.The trust boundary configuration is not correct.
Correct Answers: B

6: Based on the configuration, which two statements are true? (Choose two.)

A.The interactive traffic class will have a minimum bandwidth guarantee of 256 kbps.
B.The interactive traffic class will have a maximum bandwidth guarantee of 256 kbps.
C.If the interactive traffic class exceeds an average rate of 256 kbps, the traffic rate will be throttled down to 128 kbps.
D.This configuration allows class-based traffic shaping to lower the traffic rate in response to the BECN bit.
E.The interactive traffic class will have a min-rate (min-cir) of 128 kbps.
Correct Answers: D E

7: Which three characteristics are drawbacks to the use of a best-effort with over-provisioning backbone design? (Choose three.)
A.The design costs more to implement than a DiffServ backbone.
B.Denial of Service attacks on one service can affect all network traffic.
C.The design uses a different over-provisioning ratio for the different traffic classes.
D.It requires complex QoS mechanisms at the network edge.
E.It requires complex QoS mechanisms at the network core.
F.Unplanned network failures can cause unexpected congestion in the network.
Correct Answers: A B F

8: In a managed CE scenario, the customer’s network is supporting VoIP and bulk file transfers. According to the best practices, which QoS mechanisms should be applied on the WAN edge CE-PE 56-kbps Frame Relay link on the CE outbound direction?
A.WRR, FRTS, FRF.12, and CB-RTP header compression
B.WRR, CB-WRED, CB-Marking, FRF.12, and CB-RTP header compression
C.CBWFQ, CB-WRED, CB-Marking, CB-Policing, and FRTS
D.CBWFQ, FRTS, FRF.12, and CB-RTP header compression
E.LLQ, CB-WRED, CB-Marking, FRTS, FRF.12, and CB-RTP header compression
F.LLQ, CB-WRED, CB-Policing, and CB-TCP and CB-RTP header compressions
Correct Answers: E

9: Which QoS mechanism adds IP Precedence information for prefixes into the FIB table?
A.QoS pre-classify
D.Class-Based Marking
F.Class-Based WRED
Correct Answers: C

10: Which two commands are typically applied to the voice traffic class within a policy-map? (Choose two.)
A.shape peak {bps}
B.priority {kbps}
C.bandwidth {kbps}
D.compress header ip rtp
E.random-detect ecn
F.random-detect dscp-based
Correct Answers: B D

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