Which of these factors will prevent two routers from forming an OSPFv2 adjacency? (Choose two.)

Which of these factors will prevent two routers from forming an OSPFv2 adjacency? (Choose two.)

• Mismatched Cisco IOS versions
• Mismatched Ethernet interfaces (for example, Fa0/0 to G0/0)
• Mismatched OSPF Hello or Dead timers
• Mismatched subnet masks on the link interfaces
• Use of private IP addresses on the link interfaces

Explanation: There may be several reasons two routers running OSPF will fail to form an OSPF adjacency, including subnet masks not matching, OSPF Hello or Dead timers not matching, OSPF network types not matching, and a missing or incorrect OSPF network command. Mismatched IOS versions, the use of private IP addresses, and different types of interface ports used are not causes for an OSPF adjacency failing to form between two routers.

Exam with this question: 2.7.5 Module Quiz - Single-Area OSPFv2 Configuration