Which, three conditions are required for two FortiGate devices to form an OSPF adjacency?

Option A is correct because the OSPF interface network types determine how the routers form adjacencies and exchange LSAs on a network segment. The network types must match for the routers to become neighbors1.

Option B is correct because the OSPF router IDs are used to identify each router in the OSPF domain and to establish adjacencies. The router IDs must be unique for the routers to become neighbors2.

Option E is correct because the authentication settings control how the routers authenticate each other before exchanging OSPF packets. The authentication settings must match for the routers to become neighbors3.

Option C is incorrect because the OSPF interface priority settings are used to elect the designated router (DR) and the backup designated router (BDR) on a broadcast or non-broadcast multi-access network. The priority settings do not have to be unique for the routers to become neighbors, but they affect the DR/BDR election process4.

Option D is incorrect because the OSPF link costs are used to calculate the shortest path to a destination network based on the bandwidth of the links. The link costs do not have to match for the routers to become neighbors, but they affect the routing decisions5. References: =

1: OSPF network types

2: OSPF router ID

3: OSPF authentication

4: OSPF interface priority

5: OSPF link cost