4A0-C03: Nokia NRS II Composite Exam: IS-IS versionDemo

By Nokia · Question Mode

QuestionQ19

IS-IS Routing Protocol

A router using a link-state routing protocol discovers that one of its neighbors is no longer connected. It creates a new link-state advertisement to notify the other routers about the topology change. Which of the following is NOT an action triggered by this event?

  • A If a router receives the new link-state advertisement, it acknowledges it, stores it, and forwards it to its own neighbors.
  • B If a router receives multiple copies of the new link-state advertisement, it will simply ignore all copies received after the first one.
  • C Every router that receives the new link-state advertisement updates its age field before forwarding it.
  • D Every router that receives the new link-state advertisement runs the SPF algorithm to recalculate its shortest-path tree and its forwarding database.
Explanation

A received link-state advertisement is acknowledged, installed when newer, and flooded to other neighbors; duplicate advertisements are not reflooded, and topology changes cause shortest-path-first recalculation. Updating an advertisement's age field is not an action performed by every router merely upon receipt. In OSPF, LSAs age while held in the link-state database, and the LS age is incremented before transmission by the interface transmission delay.

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