You are configuring OSPF between two CX switches but cannot see any neighbors. Based on the output, how would you fix the problem?

Question

Exhibit

Options

• ARemove the max-metric router-lsa on-startup to allow faster formation of adjacency.
• BConfigure ip ospf network broadcast on the VLAN 182 interface.
• CConfigure no ip ospf cost 100 on the VLAN 182 interface.
• DConfigure no passive-interface vlan182 on the switch.

• A
  4% (1)
• B
  22% (6)
• C
  15% (4)
• D
  59% (16)

Explanation

Passive interfaces suppress OSPF hello packets on that interface, which is exactly how neighbors are discovered and adjacencies are formed - with VLAN 182 set as passive, the switch is silently ignoring the OSPF process on that link, making neighbor formation impossible. Running no passive-interface vlan182 lifts that suppression and allows hellos to flow in both directions.

Why the other options are wrong:

• A is wrong because max-metric router-lsa on-startup triggers stub router behavior (advertises a high metric to discourage transit traffic) but does not block hello packets or adjacency formation - neighbors still form normally.
• B is wrong because Ethernet/VLAN interfaces already default to broadcast network type on CX switches; reconfiguring the same default changes nothing about the underlying problem.
• C is wrong because OSPF cost is a metric used for path selection after adjacency is established - it has zero impact on whether neighbors discover each other in the first place.

Memory tip: Think of a passive interface as "muting" the interface for OSPF - it listens to nothing and says nothing. Whenever OSPF neighbors are missing, immediately ask: "Is the interface muted (passive)?"

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