Labels and the Label Information Base JN0-364 Practice Questions (Page 2)

Questions 6–10

1. 6foundation · easy

   What is penultimate hop popping (PHP) in MPLS?

   • AThe egress LSR removes the top label before forwarding the packet to the destination.
   • BThe ingress LSR pushes an extra label to avoid label exhaustion.
   • CThe penultimate router removes the top label before forwarding the packet to the egress LSR.
   • DThe transit LSR swaps the label with a special 'pop' label.
   Reveal Solution Discussion Select an answer first
2. 7foundation · easy

   What label operation does a transit LSR typically perform on a labeled packet as it forwards it along an LSP?

   • AReplace
   • BPush
   • CPop
   • DSwap
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4. 8application · medium

   An engineer is explaining MPLS forwarding to a junior colleague. The engineer wants to clarify that the LFIB is used for forwarding labeled packets, while the LIB is used for something else. Which statement accurately describes the primary role of the LIB?

   • AThe LIB stores only the locally assigned labels for each FEC.
   • BThe LIB stores all label bindings learned from neighbors, regardless of whether they are currently used for forwarding.
   • CThe LIB is used to perform the actual label lookup when forwarding a labeled packet.
   • DThe LIB contains the exact label operations (push, swap, pop) to apply to packets for each FEC.
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5. 9foundation · easy

   What is the primary purpose of the Label Information Base (LIB) on an MPLS router?

   • ATo store the forwarding table for labeled packets
   • BTo store label bindings learned from label distribution protocols
   • CTo store the MPLS label stack for each LSP
   • DTo store the routing table for IP prefixes
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6. 10expert · medium

   A service provider is designing an MPLS network and wants to ensure that the egress router can still apply QoS policies based on the EXP bits of the MPLS label. The provider is considering using penultimate hop popping (PHP). What is the impact of PHP on the egress router's ability to apply QoS based on EXP bits?

   • APHP has no impact on QoS because the egress router can use the IP DSCP bits instead.
   • BPHP preserves the EXP bits in the IP header, so the egress router can still use them for QoS.
   • CPHP causes the egress router to perform a label lookup, which allows it to apply QoS based on the label.
   • DPHP removes the label, so the EXP bits are lost, and the egress router cannot use them for QoS.
   Reveal Solution Discussion Select an answer first