As we know that OSPF uses Bandwidth as a criteria to select the best path to reach the destination, RIP uses HOP Count as a criteria to select best path. Then Which Type of criteria and metrics does the BGP and ISIS use to select best path?
BGP uses multiple factors, including the AS path length, next-hop reachability, local preference, and various attributes such as community values, origin type, and MED (Multi-Exit Discriminator). These attributes help BGP in determining the best path among multiple available routes.
ISIS, on the other hand, uses a metric called “Administrative Distance” (AD) to select the best path. The AD represents the trustworthiness of a routing protocol. Lower AD values indicate higher preference.