Which design principle helps reduce routing table size by aggregating routes at network boundaries?

Which design principle helps reduce routing table size by aggregating routes at network boundaries?

• A. Subnetting.
• B. VLSM.
• C. Route summarization (aggregation) at network boundaries.
• D. Static routing only.

Answer: (C)

Route summarization, or route aggregation, at network boundaries is used to reduce the size of routing tables by advertising a single, common summary route that covers many individual subnets. Instead of each subnet’s specific route being learned by distant routers, a border router announces one aggregate route that encompasses all the subnets behind it. Interior routers still know the more specific paths locally, but the outside world sees far fewer routes, which cuts memory usage, speeds up lookups, and reduces routing update traffic. This scalability is why summarization is favored at boundary points between networks or routing domains. Subnetting and VLSM are about how addresses are allocated and sliced into smaller subnets, which can actually increase the number of routes if not followed by aggregation. Static routing doesn’t provide a scalable mechanism for reducing routing table size since it relies on manually configured paths rather than automatic aggregation.

Route summarization, or route aggregation, at network boundaries is used to reduce the size of routing tables by advertising a single, common summary route that covers many individual subnets. Instead of each subnet’s specific route being learned by distant routers, a border router announces one aggregate route that encompasses all the subnets behind it. Interior routers still know the more specific paths locally, but the outside world sees far fewer routes, which cuts memory usage, speeds up lookups, and reduces routing update traffic. This scalability is why summarization is favored at boundary points between networks or routing domains.

Subnetting and VLSM are about how addresses are allocated and sliced into smaller subnets, which can actually increase the number of routes if not followed by aggregation. Static routing doesn’t provide a scalable mechanism for reducing routing table size since it relies on manually configured paths rather than automatic aggregation.