Free Cisco 642-642 Practice Test & Real Exam Questions

Exam Code/Number: 642-642
Exam Name/Title: Quality of Service (QoS)
Certification Provider: Cisco
Corresponding Certification: CCIP

Exam Questions: 87
Updated On: Jun 15, 2026

Question #1

Which QoS mechanism calculates the mean queue depth to determine its operation?

A. WFQ

B. class-based policing

C. class-based shaping

D. LLQ/CBWFQ

E. WRED

Discussion 0

Correct Answer: E Vote an answer

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Question #2

HOTSPOT

Discussion 0

Correct Answer:

Explanation:

Question #3

In which two locations is the qos pre-classify command applied to support QoS preclassification over an IPSec/GRE tunnel? (Choose two.)

A. the physical interface

B. the crypto map

C. the class-map

D. the tunnel interface

E. the policy-map

Discussion 0

Correct Answer: B,D Vote an answer

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Question #4

Which two of the following statements about CBWFQ are correct? (Choose two.)

A. The class-default queue only supports WFQ.

B. The CBWFQ scheduler provides a guaranteed amount of minimum bandwidth to each class.

C. Inside a class queue, processing is always FIFO, except for the class-default queue.

D. CBWFQ services each class queue using a strict priority scheduler.

E. Each CBWFQ traffic class is policed using a congestion aware policer.

Discussion 0

Correct Answer: B,C Vote an answer

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Question #5

HOTSPOT

Discussion 0

Correct Answer:

Explanation:

Question #6

SIMULATION - LAB

A. Please click console

Discussion 0

Correct Answer: A Vote an answer

2950-SWITCH>en
2950-SWITCH#config terminal
2950-SWITCH(config)#int fa0/1
2950-SWITCH(config-if)#mls qos trust dscp
2950-SWITCH(config-if)#exit
2950-SWITCH(config)#int fa0/11
2950-SWITCH(config-if)#mls qos trust cos
2950-SWITCH(config-if)#exit
2950-SWITCH(config)#int fa0/10
2950-SWITCH(config-if)#mls qos trust cos
2950-SWITCH(config-if)#mls qos trust device cisco-phone
2950-SWITCH(config-if)#exit

Question #7

Which two commands are typically applied to the voice traffic class within a policy-map? (Choose two.)

A. shape peak {bps}

B. compress header ip rtp

C. bandwidth {kbps}

D. random-detect ecn

E. random-detect dscp-based

F. priority {kbps}

Discussion 0

Correct Answer: B,F Vote an answer

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Question #8

A Cisco Catalyst switch has an IP phone connected to its Fastethernet0/2 port. The IP phone has an attached PC. The Fastethernet0/2 port on the switch has been configured with the commands mls qos trust cos, mls qos trust 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 through the IP phone to port Fastethernet0/2 on the switch?

A. The switch will instruct the phone to allow the packet through without modification only if the phone has been configured to do so.

B. The IP phone will, by default, overwrite the switch CoS value and mark the data packet asCoS0.

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

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

Discussion 0

Correct Answer: C Vote an answer

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Question #9

Where is the fragment size configured when using FRF.12 link fragmentation and interleaving?

A. within the MQC service-policy

B. within the MQC class-map

C. within the physical serial interface

D. within the Frame Relay map-class

E. within the MQC policy-map

F. within the logical multilink interface

Discussion 0

Correct Answer: D Vote an answer

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