Grading Checklist: OSPF Adjacency Stuck in ExStart/Exchange State

• Correctly identified the ExStart/Exchange state as a DBD exchange failure
• Checked OSPF neighbor state on both routers using show ip ospf neighbor
• Compared MTU settings on both interfaces facing each other
• Identified that MTU mismatch prevents DBD exchange from completing
• Explained the OSPF adjacency state machine and why ExStart/Exchange is where MTU matters
• Proposed fix: either match MTU on both sides or use ip ospf mtu-ignore
• Discussed the trade-offs of ip ospf mtu-ignore as a workaround vs. fixing actual MTU
• Mentioned checking for other possible causes (authentication, area mismatch, duplicate router-id)
• Noted the firmware upgrade as the likely trigger for the MTU change
• Included verification steps after applying the fix (confirm Full state, check routing table)
• Mentioned that ping success does not rule out MTU issues since pings use small packets
• Considered impact on traffic during remediation