Users on a VLAN report intermittent network disconnections lasting a few seconds. The network technician checks the switch and notices a high number of CRC errors on the port connecting to the core switch. The cable test passes. What is the most likely cause?

STP reconvergence due to topology change

Incorrect. STP reconvergence causes temporary loss of connectivity but does not produce CRC errors.

Broadcast storm caused by a loop

Incorrect. A broadcast storm would cause high traffic and latency, but CRC errors are not characteristic.

Faulty SFP transceiver on the core switch

Incorrect. While a faulty SFP can cause errors, a cable test that passes suggests the physical layer is functional; duplex mismatch is a more likely cause of CRC errors.

What does this N10-009 question test?

Access ports place end devices into a single VLAN.

What is the correct answer to this question?

The correct answer is: Duplex mismatch between the two switches — CRC errors often result from collisions or framing errors, commonly caused by a duplex mismatch where one device operates in half-duplex and the other in full-duplex. This leads to frequent collisions and retransmissions, causing intermittent connectivity. A cable test can pass even with duplex mismatch because the physical wiring is intact. STP reconvergence causes brief outages but not CRC errors. A broadcast storm would show high utilization. A faulty SFP may cause errors but typically also results in link issues or optical signal problems.

What should I do if I get this N10-009 question wrong?

Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.