4.7 Explain the Forwarding Per-Hop Behavior (PHB) for QoS Such as Classification, Marking, Queuing, Congestion, Policing, and Shaping 200-301 Practice Questions (Page 5)

Questions 21–25

1. 21expert · hard

   A network administrator is configuring QoS on a router with multiple traffic classes. The administrator wants to ensure that voice traffic gets low latency, but also wants to prevent voice traffic from consuming all available bandwidth. The administrator has decided to use LLQ. What additional configuration is required to prevent voice from starving other traffic?

   • AUse WRED on the priority queue.
   • BConfigure a policer on the priority queue to limit the amount of voice traffic.
   • CSet the queue limit to a very high value.
   • DUse strict priority scheduling without any limits.
   Reveal Solution Discussion Select an answer first
2. 22expert · hard

   A network engineer is designing QoS for a network that carries both voice and data. The engineer wants to classify voice traffic based on the DSCP value set by the IP phones. However, some IP phones are not setting the DSCP value correctly. The engineer needs to ensure that voice traffic is still prioritized. Which approach should the engineer take?

   • AUse a shaping policy to smooth voice traffic.
   • BRely on the DSCP value set by the IP phones and trust it.
   • CClassify voice traffic based on the source IP address and port numbers, and re-mark it with the correct DSCP value.
   • DApply WRED to the voice queue to drop low-priority packets.
   Reveal Solution Discussion Select an answer first
4. 23foundation · easy

   A router is configured to set the DSCP value of video traffic to AF41. Which QoS action is being performed?

   • AClassification
   • BMarking
   • CQueuing
   • DPolicing
   Reveal Solution Discussion Select an answer first
5. 24foundation · easy

   What does per-hop behavior (PHB) mean in QoS?

   • AQoS is applied only at the source and destination
   • BEach router applies QoS actions independently on a hop-by-hop basis
   • CQoS is applied only once at the first router
   • DAll routers must use the same QoS policy
   Reveal Solution Discussion Select an answer first
6. 25application · medium

   A network administrator is configuring QoS on a router that carries voice, video, and data traffic. The administrator wants to ensure that voice traffic is always transmitted before other traffic when the interface is congested. Which queuing strategy should be used?

   • AClass-based weighted fair queuing (CBWFQ) with voice in a normal queue.
   • BFirst-in, first-out (FIFO) queuing.
   • CWeighted fair queuing (WFQ) with equal weights for all traffic.
   • DPriority queuing (PQ) with voice in the high-priority queue.
   Reveal Solution Discussion Select an answer first