JN0-360 · Question #348
An IS-IS router on a broadcast medium has detected its LSDB is missing an LS PDU. Which action will the router take?
The correct answer is C. The router will send a PSNP to the router that sent it a CSNP with missing PDUs. A Partial SNP (PSNP) is similar to CSNP except that it describes only some LSPs rather than the entire database. On a P2P network, PSNP is used to acknowledge received LSPs. On a LAN network, PSNP is used to request missing or latest LSPs. Incorrect Answers: A: IS-IS Sequence…
Question
An IS-IS router on a broadcast medium has detected its LSDB is missing an LS PDU. Which action will the router take?
Options
- AThe router will send a CSNP to the router that sent it a PSNP with missing PDUs.
- BThe router will send a link-state request packet to its closest Level 1/Level2 router.
- CThe router will send a PSNP to the router that sent it a CSNP with missing PDUs.
- DThe router will send a link-state request packet to its DIS router.
How the community answered
(43 responses)- A7% (3)
- B2% (1)
- C81% (35)
- D9% (4)
Explanation
A Partial SNP (PSNP) is similar to CSNP except that it describes only some LSPs rather than the entire database. On a P2P network, PSNP is used to acknowledge received LSPs. On a LAN network, PSNP is used to request missing or latest LSPs. Incorrect Answers: A: IS-IS Sequence Number PDU (SNP) SNPs are used to maintain IS-IS LSDB by describing some or all of the LSPs in the database. The DIS periodically multicast Complete SNP (CSNP) to describe all the LSPs in the Pseudonode
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