N10-009 Question 92
Single answer1.5 Compare and contrast transmission media and transceivers.A network administrator must connect a new switch in a warehouse to the main distribution switch in an office building 700 meters away. The link must support 10 Gbps, pass through an area with heavy electromagnetic interference from industrial equipment, and use the existing switch uplink slots that accept interchangeable optical modules. Which solution best meets these requirements?
- A
Install Cat 6a copper cabling with RJ45 connectors and use 10GBASE-T ports on both switches
- B
Install multimode fiber with SFP+ SR transceivers on both switches
- C
Install single-mode fiber with SFP+ LR transceivers on both switches
- D
Install coaxial cabling with F-connectors and media converters at both ends
Show answer and explanation
Correct answer: C
Explanation
The key requirements are 10 Gbps throughput, a 700-meter building-to-building run, resistance to electromagnetic interference, and compatibility with switch slots that accept interchangeable transceivers. These factors point to fiber optic cabling with pluggable optics rather than copper. According to Ethernet physical layer standards, 10GBASE-T over twisted-pair copper is limited to 100 meters, which eliminates Cat 6a for this run. 10GBASE-SR over multimode fiber is intended for shorter distances and would not be the correct choice for a 700-meter link. 10GBASE-LR over single-mode fiber is designed for long-range 10 Gb Ethernet and comfortably supports this distance. This aligns with common enterprise best practices for inter-building backbone links: use fiber for longer distances and in environments with significant EMI, and select the appropriate transceiver type based on the fiber mode and required reach.
- A. Incorrect.
Cat 6a can support 10GBASE-T, but Ethernet over twisted-pair copper has a maximum channel length of 100 meters. A 700-meter run exceeds the standard by a wide margin. Copper is also more susceptible to electromagnetic interference than fiber, making it a poor choice in an industrial environment.
- B. Incorrect.
Multimode fiber with SFP+ SR transceivers is commonly used for short-range 10 Gb fiber links, but SR optics are intended for much shorter distances than 700 meters. Depending on fiber grade, 10GBASE-SR typically supports distances up to a few hundred meters, so this option does not reliably meet the distance requirement.
- C. Correct.
Single-mode fiber with SFP+ LR transceivers is the best choice. Single-mode fiber supports long-distance transmission, 10GBASE-LR is designed for 10 Gb links over much longer distances than 700 meters, and fiber is resistant to electromagnetic interference. Using SFP+ LR modules also matches the requirement for interchangeable optical modules in the switches' uplink slots.
- D. Incorrect.
Coaxial cabling with F-connectors is not a standard choice for a 10 Gb Ethernet switch uplink between buildings. While coax is used in some networking and broadband contexts, it is not the appropriate medium here, and adding media converters introduces unnecessary complexity without solving the EMI and standards-based switch uplink requirements.