350-401 · Question #438
Refer to me exhibit. What is the cause of the log messages?
The correct answer is B. OSPF area change. The log messages explicitly indicate an OSPF neighbor adjacency change from FULL to DOWN due to an 'Area Changed' event.
Question
Refer to me exhibit. What is the cause of the log messages?
Exhibits
Options
- Ahello packet mismatch
- BOSPF area change
- CMTU mismatch
- DIP address mismatch
How the community answered
(42 responses)- A7% (3)
- B45% (19)
- C12% (5)
- D36% (15)
Why each option
The log messages explicitly indicate an OSPF neighbor adjacency change from FULL to DOWN due to an 'Area Changed' event.
While hello packet mismatches can cause adjacency issues, the log message specifically attributes the failure to an 'Area Changed', not hello packet parameters.
The log message `OSPF-4-ADJCHG: Process 10, Nbr 192.168.12.2 on GigabitEthernet0/0 from FULL to DOWN, Neighbor Down: Area Changed` clearly states 'Area Changed' as the reason for the OSPF neighbor going down, pointing to an OSPF area ID mismatch.
An MTU mismatch would typically show a different error message, such as 'Interface MTU mismatch', which is not present in the exhibit.
An IP address mismatch would prevent neighbor discovery entirely or cause a different adjacency failure message, not explicitly 'Area Changed'.
Concept tested: OSPF adjacency troubleshooting (Area ID mismatch)
Source: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_ospf/command/ipr-ospf-cr-book/ipr-ospf-cr-s4.html
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