Refer to the exhibit. Which statement about the OPSF debug output is true?

Question

Exhibit

Options

• AThe output displays all OSPF messages which router R1 has sent to received on interface Fa0/1.
• BThe output displays all OSPF messages which router R1 has sent or received on all interfaces.
• CThe output displays OSPF hello messages which router R1 has sent received on interface Fa0/1.
• DThe output displays OSPF hello and LSACK messages which router R1 has sent or received.

• A
  4% (1)
• C
  93% (25)
• D
  4% (1)

Explanation

OSPF Debug Output Explanation

Option C is correct because the debug output shown in the exhibit specifically results from the debug ip ospf hello command, which is scoped to interface Fa0/1 - meaning it only captures OSPF Hello packets (used for neighbor discovery and keepalives) on that specific interface, not all OSPF message types.

Why the distractors are wrong:

• Option A is incorrect because the output is not showing all OSPF messages (such as DBD, LSR, LSU, LSACK) - only Hello packets are displayed.
• Option B is incorrect for two reasons: it incorrectly claims all OSPF message types are shown, and it incorrectly claims all interfaces are monitored rather than just Fa0/1.
• Option D is incorrect because LSACK (Link-State Acknowledgment) messages are not part of the Hello debug output; those would require a different debug command such as debug ip ospf packet.

Memory Tip: Think of it this way - "Hello is just a greeting." The debug ip ospf hello command only "greets" you with Hello packets, nothing more. If you need everything, use debug ip ospf packet. Always check both the message type and interface scope when reading debug outputs in exam questions.

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