In OSPF, which component distributes routing information between areas?

• A. Backbone
• B. Area Border Router
• C. Link-State Database
• D. Forwarding Database

Answer: (A)

Inter-area routing in OSPF is handled by the Area Border Router. An ABR sits at the boundary between the backbone (area 0) and other areas, and it maintains separate link-state databases for each area. It distributes routing information between areas by advertising summary routes (type-3 LSAs) into other areas and by propagating routes learned in the backbone into the connected areas. The backbone serves as the central transit area that interconnects all other areas, but it doesn’t perform inter-area distribution by itself. The Link-State Database is the area-specific collection of LSAs used to compute routes within that area, not the mechanism that spreads routes between areas. The Forwarding Database is what actually guides packet forwarding, built from the LSDB, and is not responsible for exchanging routing information between areas.