Free Cisco 300-420 Actual Exam Questions - Question 10 Discussion

This one’s tricky, but I’m thinking C. Making Area 0 L2-only fits the OSPF design rules better since Area 0 should usually be the backbone with L2 routers managing inter-area traffic. That way, you avoid mixing L1 and L2 roles in the backbone which can mess up route propagation. Options A and B don’t seem to fix the core design flaw if Area 0 is hybrid, and D feels less impactful compared to restructuring the whole backbone area’s router roles.

B/D? Making R31 an L1 router (B) might clear up area border issues if it’s currently handling multiple areas confusingly. On the other hand, turning R11 into an L2 router (D) could help if it’s not properly relaying routes between areas yet. Without knowing their exact roles and configs, both seem plausible fixes for better inter-area routing. I’d drop A since making R3 L1L2 might not solve the core issue if it’s not on the backbone or area border, and C feels drastic if Area 0 already has mixed router types working.

B tbh, making R31 an L1 router could help because it might simplify the area hierarchy and improve route summarization between areas. If R31 is currently set to L2 or L1/L2, it might be causing confusion in how routes are advertised between areas. Changing it to L1 could localize routing updates better and reduce unnecessary LSA flooding. This seems like a cleaner fix than messing with the backbone area or R11's role directly, especially if R31 acts as a border between areas.

Option C could also work since making Area 0 L2-only forces all inter-area routing through L2 routers, which might solve the route propagation problem without changing individual router levels.

Maybe D, making R11 an L2 router might help fix the routing issue shown here.