Robocert 642-642 Exam - Quality of Service

Cisco 642-642Quality of Service (QoS)

10 Q&A

Version 3.0

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www.RoboCert.com Q: 1 DRAG DROP DropAnswer & ExplanationCorrect AnswerExplanationsNo more information available


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Answer: Check RoboCert eEngine, Download from Member Center

www.RoboCert.com Q: 2 Which of the following configurations requires the use ofhierarchical policy maps?

A. the use of nested class-maps with class-based marking

B. the use of a strict priority-class queue within CBWFQ

C. the use of class-based WRED within a CBWFQ class queue

D. the use of CBWFQ inside class-based shaping

E. the use of both the bandwidth and shape statements within a CBWFQ class queue

Answer: D

www.RoboCert.com Q: 3 A Frame Relay interface has been configured foradaptive shaping with a minimum rate of 15 kbps. The current maximum transmitrate is 56 kbps.If three FECNs are received over the next 4 seconds, what will be the maximumtransmit rate after the last FECN has been received?

A. 10 kbps

B. 37 kbps

C. 7 kbps

D. 15 kbps

E. 28 kbps

F. 56 kbps


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Answer: F

www.RoboCert.com Q: 4 Based on the following show output, which statement istrue?WG1S1#sh mls qos interface fa0/1FastEthernet0/1trust state: not trustedtrust mode: trust cosCOS override: disdefault COS: 0pass-through: nonetrust device: cisco-phone

A. A Cisco IP Phone is not connected to the fa0/1 switch port.

B. All incoming DSCP markings are trusted.

C. All incoming CoS markings are trusted.

D. DSCP markings from the Cisco IP Phone are trusted.

Answer: A


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www.RoboCert.com Q: 5 In a typical converged campus network, which two of thefollowing are considered QoS best practices? (Choose two.)

A. Traffic classification and marking is performed as close to the traffic source aspossible.

B. NBAR is used at the high speed core layer to discover and classify networkapplications.

C. Catalyst switches should use weighted round robin (WRR) queuing giving the voicetraffic the highest priority.

D. Ensure voice traffic is serviced by a weighted fair queue.

E. Traffic classification and marking is performed at the high speed core layer.

F. Only a reasonable number of applications should be classified into themission-critical traffic class.

Answer: A, F

www.RoboCert.com Q: 6 A Cisco Catalyst switch has an IP phone connected to itsFastethernet0/2 port. The IP phone has an attached PC. The Fastethernet0/2 porton the switch has been configured with the commands mls qos trust cos, mls qostrust device cisco-phone, and switchport priority extend trust.What will happen to a data frame with a CoS of 5 that is sent from the PC throughthe IP phone to port Fastethernet0/2 on the switch?

A. While the packet will pass through the IP phone without modification, the switchwill, by default, override theCoS priority with the switch default CoS priority.

B. The switch will instruct the phone to allow the packet through without modificationonly if the phone has been configured to do so.

C. The IP phone will allow the data packet through without modifying theCoS settingsof the data frame.


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D. The IP phone will, by default, overwrite the switch CoS value and mark the datapacket asCoS 0.

Answer: C

www.RoboCert.com Q: 7 What does the following command accomplish?router(config-pmap-c)# shape fecn-adapt

A. enables the router to lower the shaping rate when FECN bits are received

B. enables the router to increase the shaping rate when BECN bits are received

C. enables the router to respond to FECN bits by creating test frames in the oppositedirection with the BECN bit set

D. enables the router to lower the shaping rate when BECN bits are received


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E. enables the router to respond to BECN bits by creating test frames in the oppositedirection with the FECN bit set

F. enables the router to increase the shaping rate when FECN bits are received

Answer: C

www.RoboCert.com Q: 8 To determine the bandwidth requirement for each VoIPcall, not including Layer 2 overhead, how much bandwidth per call should be addedto account for the voice signaling traffic?

A. 20 bps

B. 640 bps

C. 40 bps

D. 480 bps

E. 150 bps

F. 240 bps

Answer: E

www.RoboCert.com Q: 9 Which mechanism is used for the prioritizing, protection,and isolation of traffic based on marking?

A. policing

B. metering

C. shaping

D. classification and marking


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E. congestion avoidance

F. congestion management

Answer: F

www.RoboCert.com Q: 10 Which element is mandatory for QoS policy propagationthrough BGP operations?

A. MQC


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B. QoS pre-classify

C. policy-based routing

D. NBAR

E. CEF

F. MPLS

Answer: E

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Robocert 642-642 Exam - Quality of Service