What does route summarization do and what is a typical example?

What does route summarization do and what is a typical example?

• A. Breaks a large network into many small routes.
• B. Consolidates routes by increasing AD.
• C. Aggregates multiple subnets into a single summary route to reduce routing table size; example: 192.168.1.0/24, 192.168.2.0/24, 192.168.3.0/24 as 192.168.0.0/22.
• D. Merges two routes into a single host route.

Answer: (C)

Route summarization creates a single, larger route from several smaller subnets to shrink the routing tables routers must maintain. It’s used when the subnets share a common prefix, so you can advertise one summary route instead of many individual ones. In the given example, the three /24 networks 192.168.1.0/24, 192.168.2.0/24, and 192.168.3.0/24 all fit within the 192.168.0.0/22 block. Advertising 192.168.0.0/22 lets routers reach any of those subnets with one entry, reducing the number of routes and speeding up lookups. This approach improves scalability and efficiency, but the trade-off is less precise routing. If paths to the subnets differ, the summary route might lead to a less optimal path for some destinations. Also, ensure the subnets are compatible with a single common prefix; discontiguity can complicate or negate summarization. Not about breaking a network into more routes, not about administrative distance, and not about host routes, which are separate concepts.

Route summarization creates a single, larger route from several smaller subnets to shrink the routing tables routers must maintain. It’s used when the subnets share a common prefix, so you can advertise one summary route instead of many individual ones.

In the given example, the three /24 networks 192.168.1.0/24, 192.168.2.0/24, and 192.168.3.0/24 all fit within the 192.168.0.0/22 block. Advertising 192.168.0.0/22 lets routers reach any of those subnets with one entry, reducing the number of routes and speeding up lookups.

This approach improves scalability and efficiency, but the trade-off is less precise routing. If paths to the subnets differ, the summary route might lead to a less optimal path for some destinations. Also, ensure the subnets are compatible with a single common prefix; discontiguity can complicate or negate summarization.

Not about breaking a network into more routes, not about administrative distance, and not about host routes, which are separate concepts.