CCNA online course

Routing basics

Connected routes, static routes, and a first look at OSPF.

A router forwards packets between networks. It consults a table of prefixes and picks the longest match. Connected interfaces appear automatically. Everything else you add with a static route or a dynamic protocol.

ip route 10.20.0.0 255.255.0.0 192.0.2.1
show ip route

OSPF floods link-state advertisements inside an area and computes paths with Dijkstra. For CCNA, know areas, point-to-point versus broadcast, and why a missing network statement leaves a neighbor stuck in two-way or down.