What are two reasons that will prevent routers from forming an OSPFv2 adjacency?

ccna2-exam-answers
ccna2-answer
ccna2-exam

#1

What are two reasons that will prevent routers from forming an OSPFv2 adjacency? (Choose two.)

  1. mismatched subnet masks on the link interfaces*
  2. use of private IP addresses on the link interfaces
  3. one router connecting to a FastEthernet port on the switch and the other connecting to a GigabitEthernet port
  4. a mismatched Cisco IOS version that is used
  5. mismatched OSPF Hello or Dead timers*