Configure or Monitor CoS JN0-664 Practice Questions (Page 5)

Questions 21–25

1. 21expert · hard

   A network engineer is configuring CoS on a Juniper router that connects to a customer network. The customer requires that all traffic entering the provider network be marked with DSCP AF41 (34) for the 'af4' forwarding class. The engineer has configured a classifier on the ingress interface that maps DSCP AF41 to the 'af4' forwarding class. However, the customer reports that the DSCP value is not being set to AF41 on the egress interface. What is the most likely reason for this issue?

   • AThe classifier is not mapping DSCP AF41 to the 'af4' forwarding class correctly.
   • BThe scheduler map is not configured with the correct priority for the 'af4' forwarding class.
   • CThe drop profile is dropping the traffic before it reaches the egress interface.
   • DThe rewrite rule is not configured or applied to the egress interface.
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2. 22expert · hard

   A service provider is experiencing intermittent packet loss on a core link during peak hours. The engineer has configured a drop profile for the best-effort queue with fill-levels (50, 100) and drop-probabilities (0, 100). The engineer notices that the drop count for the best-effort queue is higher than expected, even when the queue depth is below 50%. What could be the cause of this unexpected behavior?

   • AThe drop profile is using the default interpolation, which may start dropping packets before the first fill-level point.
   • BThe queue is experiencing tail drops because the buffer size is too small, and the drop profile is not being applied correctly.
   • CThe drop profile is configured with a low drop-probability at the 50% fill-level, causing random early drops.
   • DThe drop profile is also being applied to other queues, causing them to drop packets prematurely.
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4. 23foundation · easy

   Which statement about applying CoS configurations to interfaces is true?

   • AScheduler maps are applied to interfaces to control ingress queueing.
   • BClassifiers are applied to interfaces to classify incoming traffic.
   • CDrop profiles are applied directly to interfaces.
   • DRewrite rules are applied to interfaces to classify incoming traffic.
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5. 24application · medium

   A service provider is configuring CoS on a Juniper router to support a new voice service. The voice traffic must be placed in a queue with strict-high priority, and the queue must have a guaranteed buffer size. The engineer has created a forwarding class named 'voice' and a scheduler named 'sched-voice'. What configuration is needed to ensure the 'voice' queue has strict-high priority and a guaranteed buffer?

   • AConfigure the 'voice' forwarding class with 'priority strict-high' and 'buffer-size percent 20'.
   • BConfigure the 'sched-voice' scheduler with 'priority strict-high' and 'buffer-size percent 20', then associate it with the 'voice' forwarding class using a scheduler map.
   • CConfigure a classifier that assigns voice traffic to the 'voice' forwarding class and apply it to the ingress interface.
   • DApply the 'sched-voice' scheduler directly to the interface using the [edit class-of-service interfaces] hierarchy.
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6. 25application · medium

   An engineer is configuring CoS on a Juniper MX router. They have defined four forwarding classes (ef, af1, af2, be) and created four schedulers (sched-ef, sched-af1, sched-af2, sched-be). The engineer now needs to associate each scheduler with its corresponding forwarding class and apply this association to the interface. What is the correct configuration step?

   • AApply each scheduler directly to the forwarding class using the [edit class-of-service forwarding-classes] hierarchy.
   • BCreate a classifier that maps the forwarding classes to the schedulers and apply it to the interface.
   • CCreate a scheduler map that maps each forwarding class to its scheduler, then apply the scheduler map to the interface.
   • DApply the schedulers to the interface using the [edit class-of-service interfaces] hierarchy, one per queue.
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