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Question

Difficulty: MediumNetwork Cable Types and Connectors

A network technician is assembling custom Category 6 patch cables to connect desktop computers to wall outlets. After terminating a newly cut cable, the technician uses a wire mapper to test pin continuity and discovers that pins 1, 2, 3, and 6 on one connector map to pins 3, 6, 1, and 2 respectively on the opposite connector. Which error did the technician make during cable termination?

  1. The technician wired one end of the cable using the T568A standard and the other end using the T568B standard.Answer
  2. B
    The technician attached unshielded RJ45 connectors to a shielded Category 6 twisted-pair cable run.
  3. C
    The technician stripped too much outer cable jacket, leading to excessive near-end crosstalk between pairs.
  4. D
    The technician used legacy Category 5e RJ45 modular plugs instead of Category 6 rated connectors.

Answer

The technician wired one end of the cable using the T568A standard and the other end using the T568B standard.
Combining T568A on one end of an Ethernet cable and T568B on the opposite end transposes the orange and green wire pairs. This results in pins 1 and 2 connecting to pins 3 and 6, which creates a crossover cable rather than the intended straight-through connection.

Step-by-Step Solution

1
Analyze the wire mapper results
Transmit pins 1 and 2 map to pins 3 and 6, while receive pins 3 and 6 map to pins 1 and 2.
Pin-pair transposition (1/2 <-> 3/6) indicates a crossover configuration rather than a straight-through pin arrangement.
2
Compare wiring standards T568A and T568B
T568A pinout starts with Green/White, Green (pins 1, 2) and Orange/White, Blue, Blue/White, Orange (pins 3, 4, 5, 6). T568B swaps the Green and Orange pairs.
When T568A is on one side and T568B is on the other, pins 1 and 2 (Green pair in T568A) connect to pins 3 and 6 (Green pair in T568B), creating a crossover cable.

Key Concept

T568A vs T568B Wiring Standards and Pinout Configurations
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Topics

Network Cable Types and Connectors

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