A network engineer wants to segregate three interconnected campus network via IS-IS routing. A two-layer hierarchy must be used to support large routing domains to avoid more specific routes from…

Question

Options

• AAssign a unique IS-IS NET value for each campus and configure internal campus routers with
• BDesignate two IS-IS routers from each campus to act as a Layer 1/Layer 2 backbone routers at
• CDesignate two IS-IS routers as BDR routers at the edge of each campus.
• DAssign similar router IDs to all routers within each campus.
• EChange the MTU sizes of the interface of each campus network router with a different value

• A
  81% (25)
• C
  3% (1)
• D
  6% (2)
• E
  10% (3)

Explanation

IS-IS uses a two-level hierarchical routing design: Level 1 (intra-area) and Level 2 (inter-area/backbone). To segregate three campus networks so that specific internal routes are not automatically advertised to other campuses, two actions are required. First (A), each campus must be assigned a unique IS-IS NET (Network Entity Title), which encodes the Area ID. Routers sharing the same Area ID form an L1 domain and only exchange routes within that area, preventing internal prefixes from leaking outward automatically. Second (B), two routers at the edge of each campus must be designated as L1/L2 (Level 1/Level 2) routers. These routers participate in both the local L1 area and the L2 backbone, acting as the controlled gateway between campus-internal routing and the inter-campus backbone - similar in concept to ABRs in OSPF. Option C is invalid because BDR (Backup Designated Router) is an OSPF concept, not IS-IS. Option D would cause router ID conflicts. Option E would break IS-IS adjacencies by causing MTU mismatches.

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