Cisco
400-007 · Question #224
400-007 Question #224: Real Exam Question with Answer & Explanation
The correct answer is D: Design the network so that the routers connecting to other areas are Level 1/Level 2 routers and. Using Level 1/Level 2 border routers with Level 1 internal routers partitions IS-IS topology so that internal routers carry only their area LSDB, minimizing both LSDB size and adjacency scope.
Question
Company XYZ is designing the IS-IS deployment strategy for their multiarea IS-IS domain. They want IS-IS neighbor relationships to be minimized on each network segment and want to optimize the size of the IS-IS LSDB on each router. Which can design can be used to meet these requirements?
Options
- ADesign all routers as Level 2 routers. Set the links between the routers as Level 1 with the area
- BDesign the network so that the routers connecting to other areas are Level 2 routers and internal
- CDesign the network so that all routers are Level 1 routers
- DDesign the network so that the routers connecting to other areas are Level 1/Level 2 routers and
Explanation
Using Level 1/Level 2 border routers with Level 1 internal routers partitions IS-IS topology so that internal routers carry only their area LSDB, minimizing both LSDB size and adjacency scope.
Common mistakes.
- A. Making all routers Level 2 means every router must maintain full domain-wide topology in the L2 LSDB, which maximizes LSDB size across all routers rather than optimizing it.
- B. Using only Level 2 routers at area borders without Level 1 internal routers does not partition the LSDB - internal routers would still need L2 adjacencies and carry full domain topology, defeating the goal of LSDB optimization.
- C. All Level 1 routers cannot exchange routing information between areas because inter-area reachability requires L2 adjacencies, making a multiarea IS-IS domain non-functional with this design.
Concept tested. IS-IS multiarea Level 1 and Level 2 hierarchy design
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