Routing (Layer 3)
Learn how routers select paths, build routing tables, and use OSPF, RIP, and EIGRP.
Routing is the process of selecting the best path for traffic between different networks.
A database that stores known routes and network destinations.
Routers choose the best path based on metrics like cost, hop count, and bandwidth.
Manually configured routes that do not change automatically.
Used when no specific route exists in the routing table.
Backup route with higher administrative distance.
Routers automatically learn and share routing information.
Distance vector protocol using hop count as metric.
Cisco proprietary hybrid routing protocol.
Link-state protocol using SPF (Shortest Path First) algorithm.
Most important CCNA routing protocol.
Routers form adjacencies using Hello packets.
Stores all topology information in OSPF area.
Calculates shortest path using Dijkstra algorithm.