JN0-649: Enterprise Routing and Switching, Professional (JNCIP-ENT)Demo

By Juniper · Question Mode

QuestionQ22

Interior Gateway Protocols (IGPs)

When using wide metrics, which two statements regarding route advertisement between IS-IS levels are correct?

Choose two
  • A Level 1 and Level 2 routers do not advertise Level 2 routes into the Level 1 area by default.
  • B Level 1 routes are advertised to Level 2 routers by default.
  • C If wide-metrics-only is configured, Level 1 routes are not advertised to Level 2 routers by default.
  • D Level 1 routes advertised as external routes into Level 1 are not advertised to any Level 2 routers by default.
Explanation

IS-IS leaks Level 1 routing information to Level 2 by default, but Level 2 routes are not advertised into a Level 1 area unless an explicit route-leaking policy is configured. With wide-metrics-only, extended reachability advertisements do not retain the internal-versus-external distinction needed to prevent Level 1 external routes from being leaked upward; the setting does not stop Level 1 routes from being advertised to Level 2.

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