Which OSPF network type allows for neighbor discovery on Ethernet?

The correct answer is the broadcast network type. In OSPF (Open Shortest Path First), broadcast networks, such as Ethernet, facilitate neighbor discovery by allowing routers to automatically identify and establish adjacencies with other OSPF routers on the same network segment. This is achieved through the use of multicast addresses. Specifically, routers send OSPF hello packets to the multicast address 224.0.0.5, which all OSPF routers listen to, making it easy for them to discover one another without needing manual configuration.

In contrast, point-to-point networks are used for direct connections between two OSPF routers, where neighbor discovery is straightforward but does not involve multiple routers. Point-to-multipoint networks can support multiple endpoints but require explicit configuration for neighbor discovery. Non-broadcast multi-access (NBMA) networks, such as Frame Relay, also require manual configuration for neighbor discovery, as there is no inherent broadcast capability in such environments. The broadcast network type's ability to facilitate automatic discovery is what makes it particularly effective for OSPF in Ethernet environments.