CISSP Practice Exam 2025 – Complete Prep Guide

Split horizon is a technique used in distance vector routing protocols to prevent routing loops and ensure the accuracy of routing information. By preventing a router from sending updates about a specific route back to the interface from which the route was learned, split horizon effectively reduces the chances of creating loops in the network. This is particularly significant in distance vector protocols where routers share information about what they know with their immediate neighbors.

When a router updates its routes, if it were to send information back out the same interface it received it from, it could inadvertently create a situation where conflicting information circulates, leading to routing loops. Split horizon helps to stabilize the routing process and allows the network to converge more quickly, ensuring that routers are not continuously propagating erroneous or outdated information.

The other options do not accurately represent the purpose of split horizon. While it may indirectly contribute to overall network efficiency, it does not specifically aim to enhance transmission speed or packet security. Therefore, the main function of split horizon remains the prevention of sending updates back through the interface they were learned from, which is crucial in maintaining consistent and loop-free routing tables.