220-1101 Question 192
Single answerNetwork cablesA technician is replacing a damaged network run between a switch in a wiring closet and a workstation on the other side of a warehouse. The new cable must travel about 120 meters, pass near industrial motors that generate electromagnetic interference, and support a 10 Gbps connection. Which cable type is the BEST choice for this installation?
- A
Cat 5e UTP
- B
Cat 6 UTP
- C
Cat 6a STP
- D
Multimode fiber optic
Show answer and explanation
Correct answer: D
Explanation
The key requirements are distance, bandwidth, and resistance to interference. Twisted-pair Ethernet cabling such as Cat 5e, Cat 6, and Cat 6a is generally limited to a maximum channel length of 100 meters for standard Ethernet deployments. In addition, UTP is more affected by EMI, and even shielded copper does not solve the 120-meter limitation. Fiber optic cabling is the recommended best practice when a run exceeds copper Ethernet distance limits or must pass through areas with significant electromagnetic interference. This aligns with structured cabling standards and common industry guidance such as TIA/EIA copper distance limitations and fiber use in electrically noisy environments.
- A. Incorrect.
Cat 5e UTP is not the best choice. Although Cat 5e can commonly support 1 Gbps up to 100 meters, it is not the preferred medium for a 120-meter run and is not appropriate for a reliable 10 Gbps link at that distance. Its unshielded design also makes it more susceptible to electromagnetic interference from nearby motors.
- B. Incorrect.
Cat 6 UTP is also not the best choice. Cat 6 can support 10 Gbps only over shorter distances, typically up to 55 meters depending on installation conditions, and standard Ethernet copper channel limits remain 100 meters. Because this run is 120 meters and near sources of EMI, Cat 6 UTP would not meet the distance requirement and would be vulnerable to interference.
- C. Incorrect.
Cat 6a STP is better than unshielded copper in high-EMI environments because the shielding helps reduce interference, and Cat 6a is rated for 10 Gbps up to 100 meters. However, it still does not meet the 120-meter distance requirement for a standard Ethernet copper run. A candidate might choose this option because of the EMI concern, but the distance makes it unsuitable.
- D. Correct.
Multimode fiber optic is the best choice because fiber is immune to electromagnetic interference and supports high-speed links over distances greater than 120 meters, depending on the transceivers used. For a warehouse run near industrial equipment, fiber provides both the needed distance and protection from EMI while supporting 10 Gbps.