An organization is using a link state routing that is not dependent on IP addressing. Which action enable information across area boundaries in this organization ?

Question

Options

• AAssign level 1 router interface
• BAssign level 1 routers to different areas
• CAssign level 2 router interface to the backbone area
• DAssign level 2 router to different areas
• EAssign level 2 router interface to different area

• A
  5% (1)
• C
  5% (1)
• D
  81% (17)
• E
  10% (2)

Explanation

The routing protocol described - link-state and not dependent on IP addressing - is IS-IS (Intermediate System to Intermediate System), which uses CLNS/NSAP addressing rather than IP. IS-IS has a two-level hierarchy: Level 1 (L1) routers operate within a single area and only know intra-area topology. Level 2 (L2) routers form the backbone and maintain inter-area routing information. To exchange routing information across area boundaries, you must assign Level 2 routers to the different areas - the L2 routers collectively form the backbone and pass inter-area information between them. Assigning L1 routers to different areas (B) does not help since L1 is intra-area only. The other options reference interface-level assignments that are not how IS-IS hierarchy is controlled - IS-IS level is configured per router (or per interface to make a router L1/L2), and it's the L2 router assignment across areas that enables inter-area routing.

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