JNCIS-SP: Juniper Networks Certified Specialist – Service Provider Routing (2023) — Question 20

You are troubleshooting two OSPF routers that have an adjacency that remains in the ExStart state.
What would cause this problem?

Answer options

• A. mismatched OSPF hello intervals on the OSPF interfaces
• B. mismatched authentication settings on the OSPF interfaces
• C. mismatched MTU settings on the OSPF interfaces
• D. mismatched subnet settings on the OSPF interfaces

Correct answer: C

Explanation

The correct answer is C because OSPF requires that the Maximum Transmission Unit (MTU) size be the same on all interfaces for adjacency to be formed. If the MTU settings are mismatched, OSPF will not progress beyond the ExStart state. The other options, while they may cause issues, do not directly prevent OSPF from advancing beyond this state.