Question

A network engineer manages an OSPF domain where a remote branch subnet (10.20.5.0/24) in Area 20 is reachable from the backbone (Area 0) through two different Area Border Routers, ABR-1 and ABR-2. Both ABRs advertise the summary route as Type 3 LSAs into Area 0. From a backbone router R1, the path via ABR-1 has a total cost of 30 to reach the destination, while the path via ABR-2 has a total cost of 45. Both ABRs are fully adjacent and stable. Which statement correctly describes how R1 selects its path to 10.20.5.0/24?

Accepted Answer

R1 installs the route via ABR-1 only, because OSPF selects the inter-area path with the lowest total cost to the destination.

Answer

R1 load-balances across both ABRs because inter-area routes are always treated as equal-cost regardless of metric.

Answer

R1 installs the route via ABR-2 because OSPF prefers the ABR with the higher Router ID for inter-area summaries.

Answer

R1 discards both routes and requires an intra-area path, since Type 3 LSAs cannot be used for best-path selection in Area 0.