Which area in an OSPF network is responsible for distributing routing information between areas?

• A. Backbone
• B. Area Border Router
• C. Internal Area
• D. External Area

Answer: (A)

Inter-area routing in OSPF flows through the backbone, Area 0. All other areas connect to this backbone, and summary routes are propagated between areas via the backbone using inter-area LSAs (type 3). Area Border Routers connect non-backbone areas to the backbone and help carry inter-area routes, but the actual distribution of routing information across areas happens through the backbone itself. Internal areas stay within their own domain with intra-area LSAs, and external areas handle routes learned from outside the OSPF domain via type 5 LSAs. So the backbone is the area responsible for distributing routing information between areas.