A network engineer is troubleshooting a 75-meter Category 6 (Cat6) unshielded twisted-pair (UTP) link connecting a core switch to a distribution switch. Under load, the interface experiences high frame corruption and periodic link dropping. A basic wiremapper confirms that all eight conductors are pinned correctly according to TIA/EIA-568B with continuous electrical connectivity and no open circuits or shorts. The engineer suspects a structural wire break or severe impedance anomaly located inside the building conduit between floors. Which diagnostic instrument must the engineer use to determine the exact distance along the cable run where the physical defect is located?
- A Time-Domain Reflectometer (TDR), because it sends electrical pulses along the conductors and calculates distance to anomalies based on signal reflection timing.Answer
- BA tone generator and probe kit, because tracing the modulated audio signal along the cable path identifies the exact location where the signal fades.
- CA simple continuity wiremap tester, because performing a secondary pinout check under active link conditions isolates intermittent short circuits.
- DAn optical power meter (OPM), because measuring decibel signal loss across the copper pairs identifies attenuation anomalies caused by physical bends.
Answer
A Time-Domain Reflectometer (TDR), because it sends electrical pulses along the conductors and calculates distance to anomalies based on signal reflection timing.
The option specifying a Time-Domain Reflectometer (TDR) is correct because TDR instruments transmit high-frequency electrical pulses down copper conductors. When the pulse encounters an impedance change, break, or crushed section, part of the signal reflects back to the device. By measuring the elapsed time and reflection signature, the TDR calculates the precise distance to the fault along the cable run.
Step-by-Step Solution
Key Concept
Copper Cable Fault Diagnostics using Time-Domain Reflectometry (TDR)