350-401 Question 138
Single answerA network engineer is configuring OSPF (Open Shortest Path First) on a new router in an enterprise network. The router must advertise its directly connected networks and participate in OSPF area 0. During configuration, the engineer accidentally assigns a mismatched OSPF area between this router and its neighboring router. What will happen as a result of this mismatch?
- A
The routers will establish a neighbor adjacency, but OSPF routes will not be exchanged.
- B
The routers will not form a neighbor adjacency.
- C
The routers will form a neighbor adjacency, but the directly connected networks will not be advertised.
- D
OSPF will automatically correct the area mismatch and form a neighbor adjacency between the routers.
Show answer and explanation
Correct answer: B
Explanation
In OSPF, routers must have matching area IDs on their interfaces to form a neighbor adjacency. If there is an area mismatch, the adjacency will fail to establish, and no OSPF routes will be exchanged. The configuration must be corrected to resolve the issue.
- A. Incorrect.
This is incorrect because OSPF requires matching area IDs for neighbor adjacencies to form. No OSPF routes will be exchanged if the routers fail to establish an adjacency.
- B. Correct.
This is correct because an OSPF area mismatch prevents the formation of a neighbor adjacency. OSPF neighbors must have matching area IDs along the shared link.
- C. Incorrect.
This is incorrect because OSPF requires a neighbor adjacency to be fully established before advertising any routes, including directly connected networks.
- D. Incorrect.
This is incorrect because OSPF does not have an automatic mechanism to resolve area mismatches. The configuration must be manually corrected for the adjacency to form.