CCIE Routing and Switching (legacy) — Question 7

Which three features are common to OSPF and IS-IS? (Choose three.)

Answer options

• A. They both maintain a link-state database from which a Dijkstra-based SPF algorithm computes a shortest path tree.
• B. They both use DR and BDR in the broadcast network.
• C. They both use hello packets to form and maintain adjacencies.
• D. They both use NSSA and stub type areas to scale the network design.
• E. They both have areas to form a two-level hierarchical topology.

Correct answer:

Explanation

Option A is correct as both protocols utilize a link-state database with the Dijkstra algorithm for path calculation. Option C is also correct since both OSPF and IS-IS utilize hello packets for neighbor discovery and adjacency maintenance. Option E is accurate as both protocols support areas for hierarchical design; however, the other options (B and D) are not applicable to both OSPF and IS-IS as they differ in their network operation methods.