On an IS-IS network, areas are divided by router, and a router can belong to...

Comprehensive and Detailed Step-by-Step Explanation:

IS-IS Area Division:

IS-IS divides areas byrouters, not by links. A router is assigned to a specific IS-IS area, but it can belong to multiple levels:

Level 1:Maintains the LSDB (Link State Database) for the local area only.

Level 2:Maintains the LSDB for the backbone area and exchanges routes between areas.

Behavior of a Level 1-2 Router:

A router configured as Level 1-2 must maintain two separate LSDBs:

One for intra-area routes (Level 1).

One for inter-area routes (Level 2).

Incorrect Statement:

The statement that an IS-IS router only needs to maintain the LSDB of its area is incorrect because Level 1-2 routers maintain LSDBs for both levels.