220-1201 Question #397: Real Exam Question with Answer & Explanation

Question

Marketing department users report network performance degradation in the morning and early afternoon, but sales and customer service department users do not report any issues. All structured cabling is Cat 5e. All departments are connected to a core switch. The running network configuration shows the following: Which of the following is the most likely cause of the performance issues?

Options

• AThe marketing department subnet has an error.
• BThe structured Cat 5e cabling is outdated.
• CThe interfaces are configured with Incorrect IP addresses.
• DThe marketing department Interface is running at 10/100.

Explanation

From the configuration, the Sales and Customer Service ports are hard-set to full duplex, 1000 Mbps, while the Marketing interface (GigabitEthernet0/3) is set to duplex auto and speed auto. CompTIA A+ explains that mismatched or lower-negotiated speeds and duplex settings can cause noticeable network slowdowns, collisions, and retransmissions--especially at busy times of the day when utilization is high. Because all cabling is Cat 5e, it fully supports Gigabit Ethernet, so the cabling is not the limiting factor. The IP addresses are all in the same subnet (192.168.1.0/24) and formatted correctly, so there is no subnet or addressing problem. That rules out options A and C. With speed auto, the Marketing port may be negotiating only 10/100 Mbps, or even a duplex mismatch (e.g., half duplex vs full). This would severely limit throughput compared to the gigabit links used by the other departments. In peak periods, that slower link would become congested first, which matches the users' reports of performance degradation only in Marketing. Therefore, the most likely cause is that the Marketing interface is operating at 10/100 instead of 1000 Mbps, making option D correct.

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