How does hierarchical addressing improve routing efficiency?

• A. It reduces the number of unique addresses routers need to store.
• B. It increases the number of routes stored.
• C. It makes routing decisions slower.
• D. It eliminates private addresses.

Answer: (A)

Hierarchical addressing improves routing efficiency by organizing the address space into prefixes that can be summarized. When addresses are structured into networks and subnets with common prefixes, routers can advertise and store a single route that covers many subnets, instead of maintaining a separate entry for every individual subnet or host. This aggregation reduces the size of each router’s routing table, which means faster lookups, lower memory usage, and fewer routing updates that need to be propagated. For example, instead of listing many /24 routes for individual subnets within 192.168.0.0/16, a router can use one 192.168.0.0/16 route to reach the whole block, with internal routing handling the specifics inside. This scalability is the core benefit of hierarchical addressing.