350-401 Question 341
Single answerYou are configuring OSPF on a network with multiple routers. Router R1 has two interfaces: GigabitEthernet0/0 (10.1.1.1/24) and GigabitEthernet0/1 (192.168.1.1/24). GigabitEthernet0/0 connects to Router R2, while GigabitEthernet0/1 connects to a LAN network. You want to minimize OSPF database size and avoid advertising the LAN network to other routers in the OSPF area. Which configuration should you apply to achieve this?
- A
Mark GigabitEthernet0/1 as a passive interface in OSPF.
- B
Use the 'default-information originate' command on R1.
- C
Configure OSPF area 0 as a stub area.
- D
Use a distribute-list to filter LAN routes in OSPF.
Show answer and explanation
Correct answer: A
Explanation
Marking an interface as passive in OSPF ensures that the interface does not participate in OSPF adjacency formation or route advertisement. This is the recommended approach when you want to prevent a connected network, such as the LAN in this scenario, from being advertised into the OSPF domain while still allowing the interface to remain operational for local traffic.
- A. Correct.
Marking GigabitEthernet0/1 as a passive interface prevents OSPF from forming adjacencies or advertising routes on that interface, achieving the goal of minimizing the OSPF database and preventing LAN advertisement.
- B. Incorrect.
The 'default-information originate' command is used to advertise a default route into OSPF, which does not solve the requirement to avoid advertising the LAN network.
- C. Incorrect.
Configuring OSPF area 0 as a stub area reduces the size of LSAs in the area but does not specifically prevent the LAN network from being advertised.
- D. Incorrect.
A distribute-list can filter routes, but it is used for controlling routing table updates, not OSPF LSA advertisements.