Administrative distance

A network can use more than one routing protocol, and routers on the network can learn about a route from multiple sources. Routers need to find a way to select a better path. Administrative distance number is used by routers to find out which route is better (lower number is better). For example, if the same route is learned from RIP and EIGRP, a Cisco router chooses EIGRP route and stores the route in the routing table. This is because EIGRP routes have, by default, an administrative distance of 90, while RIP route have a higher administrative distance of 120.

Connected, static & dynamic routes

Connected routes

Subnets directly connected to a router interface are added to the router’s routing table. Interface has to have an IP address configured and both interface status codes must be in the “up and up” state. A router will be able to route all packets destined for all hosts in subnets directly connected to its active interfaces.

What is IP routing?