Class of Service (CoS) JN0-105 Practice Questions (Page 1)

Questions 1–5

1. 1foundation · easy

   Which Junos CoS component is responsible for mapping incoming packets to a forwarding class?

   • AScheduler
   • BRewrite rule
   • CQueue
   • DClassifier
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2. 2application · medium

   A network administrator is designing a CoS policy for a Junos router that carries both real-time and non-real-time traffic. The administrator wants to ensure that real-time traffic is not delayed by non-real-time traffic. Which CoS mechanism should be used to achieve this?

   • AUse a rewrite rule to mark real-time traffic with a high DSCP value.
   • BUse a weighted round-robin scheduler for all queues.
   • CUse a strict-priority scheduler for the real-time queue.
   • DUse a large buffer for the real-time queue.
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4. 3application · medium

   A service provider is deploying a new Junos router at the edge of its network. The router will carry voice, video, and best-effort data traffic. The network team wants to ensure that voice packets experience minimal delay and jitter, while video traffic should be prioritized over best-effort data but not at the expense of voice. Which CoS mechanism should be configured to achieve this behavior?

   • AUse a single classifier to mark all traffic with the same forwarding class, then rely on the default scheduler.
   • BApply a rewrite rule to change the DSCP values of all packets to the same value.
   • CConfigure a single forwarding class for all traffic and apply a single scheduler with a high transmit rate.
   • DConfigure separate forwarding classes for voice, video, and data, and apply schedulers with appropriate priorities and buffer sizes.
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5. 4foundation · easy

   Which statement correctly describes the basic operation of CoS in Junos?

   • ACoS only works on outbound traffic and cannot affect inbound traffic
   • BCoS classifies traffic and applies different forwarding treatments based on that classification
   • CCoS marks packets with a higher TTL to ensure they are forwarded first
   • DCoS uses a single queue for all traffic and applies the same priority to every packet
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6. 5expert · hard

   A network engineer is troubleshooting a CoS issue on a Junos router. The engineer has configured a classifier to map DSCP AF41 to the 'premium' forwarding class. However, when checking the queue statistics, the engineer sees that packets with DSCP AF41 are being counted in the 'best-effort' queue. What is the most likely cause of this issue?

   • AThe forwarding class 'premium' is not mapped to a queue.
   • BThe scheduler map is not applied to the egress interface.
   • CThe classifier is not applied to the ingress interface.
   • DThe rewrite rule is not configured on the egress interface.
   Reveal Solution Discussion Select an answer first