JN0-351: Enterprise Routing and Switching, Specialist (JNCIS-ENT)Demo

By Juniper · Question Mode

QuestionQ24

IS-IS

You are setting up an IS-IS IGP network, but the IS-IS adjacencies are not establishing.

In this scenario, which two reasons could cause this issue?

Choose two
  • A MTU is not at least 1492 bytes.
  • B IP subnets are not a /30 address.
  • C The Level 2 routers have mismatched areas.
  • D The Io0 interface is not included as an IS-IS interface.
Explanation

Junos IS-IS hello PDUs are padded to 1492 bytes, so the connecting interface must support at least that MTU for adjacency formation. The loopback interface (lo0) must also be included in the IS-IS configuration because it provides the router’s NET; IS-IS does not function correctly when it is omitted. Level 2 routers do not need matching area addresses, and the IPv4 subnet prefix length is not an IS-IS adjacency requirement.

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