OSPF Network Types

Point-to-multipoint is treated as a collection of point-to-point links and thus no DR/BDR is required.

Point-to-Point is a single link and no election is needed.

Broadcast: OSPF routers on broadcast networks will elect a DR and a BDR (since it is multiaccess) – OSPF packets are multicast.

NBMA: Routers will elect DR and BDR (since it is multiaccess), but since it is a non-broadcast, routers will have to communicate via unicast rather than multicast.