Duplex Mismatch: Identifying Symptoms and Solutions

Symptoms of Duplex Mismatch

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Which symptom most commonly indicates that two connecting interfaces are configured with a duplex mismatch?



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A. B. C. D.


The correct answer is C. Late collisions on the interface.

A duplex mismatch occurs when two connected devices operate at different duplex modes - half duplex or full duplex. Duplex mode refers to the ability of a network interface to send and receive data simultaneously.

Symptoms of a duplex mismatch include slow network performance, intermittent connectivity, and in some cases, complete network failure. However, the most common indication of a duplex mismatch is the occurrence of late collisions on the interface.

Late collisions are a type of collision that occurs when a network interface tries to transmit data after the carrier sense threshold has been reached. In other words, the transmitting device does not receive an acknowledgment that the data has been transmitted correctly and retransmits it. Late collisions occur when there is a mismatch between the duplex mode of two connecting interfaces.

When a full-duplex interface is connected to a half-duplex interface, the full-duplex interface will transmit data while simultaneously receiving data. However, the half-duplex interface can only transmit or receive data at a given time. If the half-duplex interface transmits data while the full-duplex interface is transmitting data, a collision occurs, and a late collision is reported.

In summary, if you encounter late collisions on a connected interface, it is likely that the two interfaces are configured with a duplex mismatch.