Final answer:
Route summarization, also known as route aggregation, reduces the routing table size by consolidating multiple routes into a single advertisement for contiguous subnets. This optimizes routing and simplifies network topology.
Step-by-step explanation:
The process that reduces the size of the routing table by advertising a single route as the destination for a group of contiguous subnets is known as route summarization. This technique is also referred to as route aggregation. Route summarization helps in optimizing the routing process by consolidating multiple routes into a single advertisement, which decreases the number of routes a router needs to handle. This helps in efficient utilization of the network resources and simplifies the network topology from a routing perspective. Not to be confused with route redistribution, which is the process of sharing routes between different routing protocols, or route fragmentation, which doesn't pertain to reducing routing table size.