Which statement best describes the effect of OSPF area design on routing?

• A. Areas provide hierarchical routing; ABRs summarize routes between areas and route convergence is faster within areas.
• B. Areas are used to map an IP address to a specific interface on a router.
• C. Areas determine how traffic is shaped using QoS policies.
• D. Areas replace router IDs in OSPF.

Answer: (A)

OSPF uses a hierarchical design with areas to scale routing. By dividing the network into areas, the routing updates and SPF calculations stay within a smaller, localized scope, which makes convergence faster inside an area. The backbone area (Area 0) ties all other areas together, and border routers (ABRs) connect these areas and summarize routes as they cross area boundaries, keeping inter-area routing efficient and scalable. This combination—hierarchical structure, faster intra-area convergence, and ABR-based route summarization between areas—is what area design is all about.

Areas don’t assign IPs to interfaces; that’s a function of interface configurations and routing decisions. QoS policies are separate from how OSPF organizes routing areas. And router IDs aren’t replaced by areas; IDs remain identifiers for routers within the OSPF domain.