Use the Syntax Checker in Figure 3 to verify the R2 and R3 neighbors using the show ip ospf neighborcommand.
Two routers may not form an OSPF adjacency if:
• The subnet masks do not match, causing the routers to be on separate networks.
• OSPF Hello or Dead Timers do not match.
• OSPF Network Types do not match.
• There is a missing or incorrect OSPF network command.