Question

Difficulty: MediumTroubleshooting Physical Cabling and Connectors

A network technician is inspecting a newly installed Category 6A copper link between a patch panel and an end-user wall outlet that fails to negotiate a 10Gbps connection and frequently drops packets. A cable certifier report indicates a wire map failure with an open circuit on pins 4 and 5, along with severe Near-End Crosstalk (NEXT) on pairs 1-2 and 3-6. Which of the following physical layer conditions are the most likely causes of these test results? (Select TWO.)

  1. Excessive untwisting of wire pairs near the patch panel punch-down block termination pointAnswer
  2. An unseated conductor or incomplete crimp on pins 4 and 5 inside the modular connectorAnswer
  3. C
    Using a tone generator and inductive probe to pinpoint the exact distance to the physical break
  4. D
    An auto-negotiation duplex mismatch between the switch port and the workstation network card

Answer

The correct physical layer causes are excessive untwisting of wire pairs near the termination point and an unseated conductor on pins 4 and 5.
Excessive untwisting of wire pairs removes the inherent noise cancellation of twisted-pair media, inducing high NEXT interference. In addition, an open reading on specific pins indicates an incomplete pin crimp or unseated conductor preventing physical continuity.

Step-by-Step Solution

1
Analyze the cause of Near-End Crosstalk (NEXT) failure.
Excessive untwisting of pair conductors near termination points degrades inductive noise cancellation.
Maintaining precise pair twists close to the punch-down or modular plug is essential for differential signal noise rejection.
2
Analyze the cause of the wire map open failure on pins 4 and 5.
Identifies an electrical open circuit at pin positions 4 and 5.
A poor pin crimp or unseated wire prevents electrical contact between the conductor and the jack pin.

Key Concept

Physical layer copper cable troubleshooting, crosstalk mitigation, and wire map diagnostics
Estimated Time:1m 30s
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