What is the role of route preference?

Route preference, also known as administrative distance, is a numerical value assigned to routing protocols to indicate their trustworthiness. When a router learns about the same destination prefix from different routing protocols, it uses the route preference value to decide which protocol's route to install into the routing table, with a lower value indicating higher preference.

While route preference contributes to determining the preferred path, its specific role is to resolve conflicts between *different* protocols, not the general process of path selection which also involves metrics within a single protocol.

Route preference resolves conflicts between different protocols; equal-cost multi-path (ECMP) is the mechanism used to select the best route among multiple equal-cost paths *within the same protocol* or with the same preference value.

Route preference determines which specific route is installed into a routing table for forwarding, not which routing table to use overall for a particular address family.