Latest CCNP 642-637 Real Exam Download 31-40



At what point in a VoIP network are the existing class of service or differentiated services code point values considered valid and are used throughout the rest of the network?


A.      trust boundary

B.      marking boundary

C.      access layer

D.      distribution layer


Answer: A




Which QoS methodology combines strict priority queuing with class-based weighted fair queuing?


A.      IP RTP Priority

B.      Multilink PPP

C.      IP Frame Relay RTP Priority

D.      RSVP

E.       LLQ


Answer: E




What are the three acceptable values for one-way delay, jitter, and packet loss in a VoIP network? (Choose three.)


A.      0-400 ms for delay

B.      1 packet loss

C.      20 ms for jitter

D.      0-150 ms for delay

E.       1 percent packet loss

F.       30 ms for jitter


Answer: D,E,F




What are the PHBs that DiffServ use?


A.      resource reservation and admission control

B.      default, AF, and EF PHBs

C.      AF, EF, and CS PHBs

D.      AF and EF PHBs

E.       default, AF, EF, and CS PHBs


Answer: E




What are two benefits of using the DiffServ model? (Choose two.)


A.      DiffServ is a flow-based architecture.

B.      DiffServ is highly scalable.

C.      DiffServ keeps flow state on each node in the network.

D.      DiffServ supports a large number of service classes.

E.       DiffServ uses repetitive signaling for each flow.


Answer: B,D




What is the decimal equivalent of the DSCP value AF21?


A.      16

B.      17

C.      18

D.      21


Answer: C




If a packet is marked with an IP precedence value of 011, what is the corresponding binary DSCP class-selector value?


A. 000011

B. 011110

C. 011000

D. 011010

E. 011100


Answer: C




In which situation would the trust boundary be located at the access layer?


A.      if the endpoints, both IP phones and PCs, are incapable of marking traffic properly

B.      if PCs are switched through an IP phone and the IP phone traffic can be trusted to mark both traffic streams properly

C.      if the access layer switch cannot trust or re-mark incoming traffic from endpoints properly

D.      if there are endpoints that cannot be trusted and connect directly to the distribution layer


Answer: A




Refer to the exhibit.

clip_image002How does a switch port that receives marked traffic from a Cisco IP phone use the mls qos trust cos command?


A.      The CoS setting is modified according to the CoS-to-DSCP map.

B.      CoS is used to select the ingress and egress queues.

C.      For non-IP packets, the CoS is set to 7 and DSCP-to-CoS mapping is not applied.

D.      The DSCP-to-CoS map is applied.


Answer: A




Refer to the exhibit. Your company’s QoS policy states that all traffic that is arriving at access layer switches from IP phones should be marked with a DSCP value of 46 and that all untagged traffic that is arriving from a PC that is attached to an IP phone should be marked with a CoS value of 1. Which two options will satisfy the requirements for the CoS-to-DSCP map and are the correct QoS commands? (Choose two.)


A.      mls qos 1

B.      mls qos map cos-dscp 0 10 18 26 34 46 48 56

C.      mls qos cos 1

D.      mls qos map dscp 0 8 16 26 32 40 48 56

E.       mls qos map cos 0 8 18 26 40 48 50 56

F.       mls qos dscp 1


Answer: B,C



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