In an IP routing environment, which of the following is a primary result and benefit of route aggregation (route summarization)?

Introduction / Context:
This question focuses on the concept of route aggregation, also known as route summarization, in IP networks. Aggregating routes allows a router to advertise a single summary route that represents multiple more specific networks, which can dramatically improve the scalability and performance of large routing domains such as service provider backbones and enterprise cores.

Given Data / Assumptions:
- Multiple contiguous network prefixes can be represented by a single summary prefix.
- Routing protocols such as OSPF, EIGRP, and BGP support various forms of summarization.
- The question asks about the main result of route aggregation, not its configuration details.
- We assume that summarization has been done correctly so that reachability is preserved for the covered networks.

Concept / Approach:
Route aggregation reduces the number of entries that routers need to maintain in their routing tables. Instead of tracking each small network separately, a router advertises and stores a single larger prefix that covers all of them. This leads to smaller routing tables, which reduces memory consumption and speeds up route lookup operations. It can also produce more stable routing behavior by limiting the propagation of small changes in part of the network.

Step-by-Step Solution:
Step 1: Consider an example where a router knows four /24 networks that are contiguous and can be summarized into a single /22.Step 2: Without summarization, both that router and its neighbors must maintain and process four separate routes.Step 3: With summarization, the router can advertise a single /22 route representing all four /24 networks.Step 4: This directly decreases the number of routing table entries from four to one for that set of networks.Step 5: As the network grows, repeating this practice across many areas leads to significantly smaller and more manageable routing tables.

Verification / Alternative check:
Service providers routinely use summarization at the edges of their networks to prevent detailed internal routes from flooding the global Internet routing table. If every small subnet were advertised individually, core routers would need enormous memory and CPU resources to keep up. The fact that summarization is widely used in practice to keep tables under control confirms that smaller routing tables are a key benefit.

Why Other Options Are Wrong:
More complete routing tables actually means more specific entries, which is the opposite of what summarization aims to achieve. Summarization reduces, not increases, routing table size and thus can reduce memory usage instead of increasing it. Proper summarization also tends to stabilize CPU usage by preventing frequent flapping of individual routes. Automatic failover requires redundancy and appropriate metrics or tracking, not just summarization; while summarization can be part of a resilient design, it does not by itself implement failover.

Common Pitfalls:
Some learners wrongly equate more prefixes with better routing information, ignoring the scaling challenges this creates. Others worry that summarization always causes loss of detail that will break routing, but when used at the right boundaries it preserves connectivity while simplifying tables. It is important to remember that the main goal of summarization is to decrease routing table size and improve scalability, not to provide more detailed information.

Final Answer:
The primary result of route aggregation is smaller, more scalable routing tables.