Which command configures OSPF as passive on VLAN interfaces 20, 30, and 40?

Which command configures OSPF as passive on VLAN interfaces 20, 30, and 40?

• A. vlan 20,30,40 ospf passive
• B. interface vlan 20,30,40 ip ospf passive
• C. router ospf 1 area 0 passive-interface vlan 20,30,40
• D. router ospf 1 area 0 redistribute local

Answer: (B)

OSPF passive interfaces are used to prevent OSPF from forming neighbors and from sending Hellos on those interfaces. When you mark an interface as passive, it still carries routing information learned from other active interfaces, but it won’t actively participate in OSPF neighbor discovery on that link. To apply this to VLAN interfaces 20, 30, and 40, you configure the passive setting on each interface so that the SVIs for those VLANs don’t become OSPF neighbors. The approach shown—configuring ip ospf passive on the VLAN interfaces themselves (often written as interface vlan 20,30,40 followed by ip ospf passive)—directly targets those SVIs. This is why it’s the best fit: it precisely disables OSPF adjacencies on the specified VLAN interfaces. Other patterns either use syntax that isn’t valid on many devices for listing multiple interfaces or apply passive settings at the router process level, which is not the per-interface control you want. Redistributing local routes has nothing to do with making interfaces passive.

OSPF passive interfaces are used to prevent OSPF from forming neighbors and from sending Hellos on those interfaces. When you mark an interface as passive, it still carries routing information learned from other active interfaces, but it won’t actively participate in OSPF neighbor discovery on that link.

To apply this to VLAN interfaces 20, 30, and 40, you configure the passive setting on each interface so that the SVIs for those VLANs don’t become OSPF neighbors. The approach shown—configuring ip ospf passive on the VLAN interfaces themselves (often written as interface vlan 20,30,40 followed by ip ospf passive)—directly targets those SVIs. This is why it’s the best fit: it precisely disables OSPF adjacencies on the specified VLAN interfaces.

Other patterns either use syntax that isn’t valid on many devices for listing multiple interfaces or apply passive settings at the router process level, which is not the per-interface control you want. Redistributing local routes has nothing to do with making interfaces passive.