What is the administrative distance of an IS-IS route?

The administrative distance of an IS-IS (Intermediate System to Intermediate System) route is 115.

Explanation:

Administrative distance is a value used by routers to select the best path when there are two or more different routes to the same destination from two different routing protocols. It’s essentially a measure of the trustworthiness of the source of the routing information, with lower values being preferred over higher values.

IS-IS (Intermediate System to Intermediate System) is a routing protocol designed to move information efficiently within a computer network, a group of physically connected computers or similar devices. It is widely used in large networks, particularly within service provider environments.

The administrative distance for IS-IS is set to 115 by default on most routing devices. This is compared to other routing protocols like OSPF (Open Shortest Path First) which has a default administrative distance of 110, EIGRP (Enhanced Interior Gateway Routing Protocol) which is 90 for internal routes, and BGP (Border Gateway Protocol) which is 20 for external routes and 200 for internal routes. The administrative distance is a crucial factor in route selection, with the route having the lowest administrative distance being preferred if multiple routes exist to the same destination.