An OSPF network type is an interface setting that controls communication behavior on a connected network. It affects hello and dead timers, neighbor discovery, DR/BDR elections, and adjacency formation. section 18.3.2
For CCNA study, focus on broadcast and point-to-point:
- Broadcast is the default for Ethernet interfaces. Routers dynamically discover neighbors, elect a DR and BDR, and establish full adjacencies with the DR and BDR; other neighbors remain 2-Way. section 18.3.2
- Both types use default hello and dead timers of 10 and 40 seconds. A physical interface failure removes the neighbor immediately; the dead timer matters when the interface stays up but hellos stop. section 18.3.2
Changing a two-router Ethernet link
On both routers, enter interface configuration mode and apply `ip ospf network point-to-point`. Verification with `show ip ospf neighbor` shows a `FULL/-` relationship, confirming a full adjacency without DR/BDR election.
