Which type of router can provide connectivity between areas in an IS-IS domain?
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A. B. C. D.B
IS-IS (Intermediate System-to-Intermediate System) is a link-state interior gateway routing protocol used by many large service providers and enterprises. It is used to route traffic within an Autonomous System (AS), typically within a single provider or organization, and is used to route both IP and other protocols.
In IS-IS, routers are organized into levels, with each level representing a different scope of routing. Level 1 (L1) routers are responsible for routing within a single area, while Level 2 (L2) routers are responsible for routing between areas. An area is a grouping of routers that share a common set of L1 routers, and all L1 routers within an area have full knowledge of the topology of that area.
To provide connectivity between areas in an IS-IS domain, a router must be able to perform Level 2 routing and have adjacencies in more than one area. This means that option B, "a Level 2 router with adjacencies in more than one area," is the correct answer.
Option A, "a Level 1 router with adjacencies within a single area," is incorrect because Level 1 routers do not have the ability to route between areas.
Option C, "an area border router with adjacencies in more than one area," is incorrect because an area border router is simply a router that has at least one interface in more than one area and does not necessarily have the ability to perform Level 2 routing.
Option D, "a Level 2 router with adjacencies in a single area," is also incorrect because a Level 2 router must have adjacencies in more than one area to perform routing between areas.