CompTIA A+ Core 1 (220-1201)Hardware and Network TroubleshootingHard

A technician is troubleshooting a client's desktop that intermittently loses network connectivity. The client reports that the issue seems to occur more frequently during peak network usage hours. The technician suspects a duplex mismatch. Which of the following tools would BEST confirm this suspicion?

  1. ATone generator and probe.
  2. BLoopback adapter.
  3. CCable tester.
  4. DNetwork analyzer.
Show answer & explanation

Correct answer: D. Network analyzer.

A duplex mismatch occurs when one side of a network connection operates in full-duplex mode and the other in half-duplex mode, leading to excessive collisions and poor performance. A network analyzer (or packet sniffer) can capture network traffic and detect high collision rates, runts, or late collisions, which are strong indicators of a duplex mismatch.

Why the other options are wrong

  • A. A tone generator and probe are used to locate cables, not diagnose network protocol issues like duplex mismatch.
  • B. A loopback adapter tests the functionality of a network interface card (NIC) by sending data back to itself, but it does not analyze network traffic in an active connection.
  • C. A cable tester verifies cable integrity (opens, shorts, crossed pairs) but cannot detect duplex mismatch.

Duplex Mismatch Diagnosis

Identifying a network configuration error where two connected devices operate at different duplex settings, causing performance issues.

  • Leads to excessive collisions, retransmissions, and slow speeds.
  • Symptoms are intermittent connectivity, poor throughput.
  • Best diagnosed by observing collision rates with a network analyzer.

Memory trick: When the network's ghosting, a 'sniffer' will show what's boasting.

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