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 1)

Questions 1–5

1. 1application · medium

   A network administrator is configuring QoS on a router that has four classes of traffic: voice, video, business data, and best effort. The administrator wants to ensure that voice and video are always sent before business data and best effort, but also wants to prevent voice and video from starving the other classes. Which queuing strategy should be used?

   • AFirst-in, first-out (FIFO) queuing.
   • BWeighted fair queuing (WFQ) with all classes having equal weights.
   • CPriority queuing (PQ) with voice and video in the high-priority queue.
   • DClass-based weighted fair queuing (CBWFQ) with voice and video in a priority queue and a policer to limit their rate.
   Reveal Solution Discussion Select an answer first
2. 2foundation · easy

   Why does a router mark packets with a DSCP value?

   • ATo identify the traffic class for local classification
   • BTo buffer excess traffic and smooth bursts
   • CTo drop packets that exceed a configured rate
   • DTo indicate the priority of the packet to downstream devices
   Reveal Solution Discussion Select an answer first
4. 3foundation · easy

   A QoS mechanism buffers excess traffic and transmits it later to smooth bursts and conform to a specified rate. Which mechanism is this?

   • AWRED
   • BClassification
   • CShaping
   • DPolicing
   Reveal Solution Discussion Select an answer first
5. 4application · medium

   A network administrator is configuring QoS on a router that connects to a service provider. The service provider's network drops packets that exceed a certain rate. The administrator wants to avoid packet drops by smoothing out bursts of traffic before they are sent to the provider. Which mechanism should be used on the router's egress interface?

   • AShaping to the provider's rate limit.
   • BWRED on the egress interface.
   • CPolicing with a conform-action of transmit and an exceed-action of drop.
   • DPriority queuing with the provider's traffic in the high-priority queue.
   Reveal Solution Discussion Select an answer first
6. 5application · medium

   A company runs a VoIP service and wants to ensure that voice traffic receives priority treatment across the network. The network team has decided to mark voice packets at the access layer. Which action should the team take to ensure that downstream routers recognize and prioritize the voice traffic?

   • AConfigure an ACL to match voice traffic and set the DSCP value to EF.
   • BEnable tail drop on the voice queue to manage congestion.
   • CUse WRED on the voice queue to drop low-priority packets.
   • DApply a shaping policy to the voice traffic to smooth bursts.
   Reveal Solution Discussion Select an answer first