Rewrite Rules JN0-664 Practice Questions (Page 1)

Questions 1–5

1. 1application · medium

   An engineer is configuring CoS on a Junos router. They have created a rewrite rule named 'sp-rewrite' that maps the forwarding class 'expedited-forwarding' to DSCP 46. They then applied this rule to interface ge-0/0/1 with the command 'set class-of-service interfaces ge-0/0/1 unit 0 rewrite-rules dscp sp-rewrite'. After committing, they send test traffic through the interface and observe that the DSCP value on the outgoing packets is unchanged. What is the most likely reason for this behavior?

   • AThe router must be rebooted for the rewrite rule to take effect on the interface.
   • BThe rewrite rule was applied to the wrong interface or unit, so it is not affecting the traffic on ge-0/0/1.
   • CThe rewrite rule is only applied to the forwarding class 'expedited-forwarding', and the test traffic is in a different forwarding class.
   • DThe rewrite rule must also be applied to the input direction of the interface to take effect.
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2. 2foundation · easy

   Which Junos configuration stanza is used to define a rewrite rule that maps forwarding classes to DSCP values?

   • Aclass-of-service classifiers dscp
   • Bclass-of-service schedulers dscp
   • Cclass-of-service forwarding-classes dscp
   • Dclass-of-service rewrite-rules dscp
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4. 3foundation · easy

   What is the primary purpose of a rewrite rule in Junos CoS?

   • ATo drop packets that exceed the configured bandwidth limit.
   • BTo classify incoming packets based on their existing CoS markings.
   • CTo queue packets into different forwarding classes based on their priority.
   • DTo mark packets with a new CoS value before they are transmitted on an interface.
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5. 4application · medium

   A service provider is deploying a new MPLS-enabled PE router that connects to a customer site. The customer's edge router is not MPLS-aware and expects to receive traffic marked with IEEE 802.1p priorities that match the per-hop behavior (PHB) the provider assigned internally. The PE router currently classifies inbound traffic with a BA classifier and forwards it across the MPLS core. What must the network engineer configure on the PE router so that traffic sent toward the customer edge carries the correct 802.1p values?

   • AApply a rewrite rule to the customer-facing interface that maps the internal forwarding class and loss priority to the appropriate 802.1p code point.
   • BConfigure a firewall filter on the customer-facing interface to re-mark the 802.1p bits of all outgoing packets to a fixed value.
   • CApply the same BA classifier to the customer-facing interface in the output direction to ensure the 802.1p bits are preserved.
   • DEnable MPLS EXP classification on the PE router so the customer edge can infer the priority from the MPLS label.
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6. 5foundation · easy

   Which statement accurately describes the role of rewrite rules in a Junos CoS configuration?

   • AThey assign forwarding classes to packets as they enter the router.
   • BThey determine which queue a packet is placed into based on its DSCP value.
   • CThey modify the CoS values of packets as they are transmitted out of an interface.
   • DThey control the amount of bandwidth allocated to each forwarding class.
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