Implementing Cisco Service Provider Advanced Routing Solutions (SPRI) — Question 73

Which difference must an engineer consider when choosing whether to implement OSPF or IS-IS as the routing protocol on the network?

Answer options

• A. The OSPF DR election process is deterministic, and the IS-IS DS election process is not deterministic.
• B. To support fast convergence, OSPF uses the LSA arrival timer and IS-IS uses the PRC-interval timer.
• C. IS-IS supports ordinary, stub, totally-stub, and NSSA areas, but OSPF supports only stub areas.
• D. IS-IS links are associated with either a Level 1 area or a Level 2 area at one time, but OSPF links are associated with multiple areas at one time.

Correct answer: B

Explanation

The correct answer is B because OSPF's LSA arrival timer is designed to help achieve fast convergence, while IS-IS uses the PRC-interval timer for similar purposes. Option A is incorrect because both processes have their own deterministic features. Option C is wrong as OSPF supports more than just stub areas, and option D misrepresents the area association capabilities of OSPF and IS-IS.