MPLS Packet Header JN0-364 Practice Questions (Page 1)

Questions 1–5

1. 1application · medium

   A service provider is deploying MPLS in the core to carry both IPv4 and IPv6 customer traffic. The PE routers must push a transport label and a service label for each packet. While capturing packets on the core link, a network engineer observes that the outer label has the S bit set to 0. What does this indicate about the packet?

   • AThe outer label is the service label, and the transport label is below it.
   • BThe packet carries at least one more label after the outer label in the stack.
   • CThe packet carries only one label, and the outer label is the bottom of the stack.
   • DThe packet has been dropped because the label stack is malformed.
   Reveal Solution Discussion Select an answer first
2. 2application · medium

   A service provider is implementing class-of-service (CoS) in its MPLS core. The provider wants to prioritize voice traffic over best-effort data. The PE router marks voice packets with a specific EXP value. Which field in the MPLS shim header carries this marking, and how many bits does it use?

   • AThe S field, 1 bit
   • BThe TTL field, 8 bits
   • CThe Label field, 20 bits
   • DThe EXP field, 3 bits
   Reveal Solution Discussion Select an answer first
4. 3application · medium

   A network engineer is troubleshooting an MPLS network and examines a captured packet. The label value in the shim header is 16. What is the significance of this label value?

   • AIt is the first usable label value for regular MPLS labels, as values 0–15 are reserved.
   • BIt is a reserved label used for explicit null, indicating that the payload must be sent with the original IP TTL.
   • CIt is a router alert label, indicating that the packet must be examined by every LSR.
   • DIt is an invalid label because the label value must be at least 1024.
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5. 4foundation · easy

   What is the primary role of the 3-bit EXP field in the MPLS shim header?

   • ATo carry class-of-service and QoS information
   • BTo identify the payload protocol type
   • CTo provide error detection for the MPLS header
   • DTo indicate the length of the MPLS label stack
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6. 5foundation · easy

   What happens when a router performs a label pop operation on an MPLS packet?

   • AIt removes the top label and processes the next header.
   • BIt adds a new label on top of the existing stack.
   • CIt discards the entire packet.
   • DIt replaces the top label with a new label value.
   Reveal Solution Discussion Select an answer first