300-320 · Question #376
Which OSPF option can you configure to connect two parts of a partitioned backbone through a nonbackbone area?
The correct answer is B. a virtual link. In OSPF, all non-backbone areas must connect directly to Area 0 (the backbone). If the backbone becomes partitioned - meaning two segments of Area 0 are not physically connected - OSPF routing between those segments breaks down. A virtual link provides the solution: it creates…
Question
Which OSPF option can you configure to connect two parts of a partitioned backbone through a nonbackbone area?
Options
- Aroute summarization
- Ba virtual link
- Can NSSA
- Da static OSPF neighbor
How the community answered
(33 responses)- A3% (1)
- B91% (30)
- C6% (2)
Explanation
In OSPF, all non-backbone areas must connect directly to Area 0 (the backbone). If the backbone becomes partitioned - meaning two segments of Area 0 are not physically connected - OSPF routing between those segments breaks down. A virtual link provides the solution: it creates a logical point-to-point connection between two Area Border Routers (ABRs) that both touch Area 0 on one side and a common transit non-backbone area on the other. This effectively extends Area 0 across the transit area, reconnecting the partitioned backbone. Route summarization (A) reduces LSA flooding but does not reconnect partitioned areas. An NSSA (C) allows limited external route injection into a stub-like area but does not fix backbone partitioning. A static OSPF neighbor (D) is used for non-broadcast networks and does not address backbone partitioning.
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