CompTIA Network+ (N10-009)Network ImplementationEasy
A technician needs to connect two buildings located 2 kilometers apart using fiber optic cable, with no repeaters or amplifiers along the run. Which cable type should be selected?
- AMultimode OM4
- BMultimode OM1
- CTwinaxial cable
- DSingle-mode OS2
Show answer & explanationAnswer & explanation
Correct answer: D. Single-mode OS2
Single-mode fiber (OS2) uses a laser light source and a narrow core, allowing transmission distances of 10 km or more without repeaters, making it ideal for a 2 km run. Multimode fiber (OM1/OM4) is limited to a few hundred meters at typical data rates, and twinaxial cable is a copper medium suited only for very short runs.
Why the other options are wrong
- A. OM4 multimode improves on OM1 but still tops out well under 1 km at high speeds.
- B. OM1 multimode supports only a few hundred meters at best.
- C. Twinax is a short-range copper cable used within data centers, not for building-to-building links.
Single-Mode vs Multimode Fiber
Single-mode fiber uses a narrow core and laser light for long-distance transmission (10+ km), while multimode fiber uses a wider core and LED/laser light suited for short distances (up to ~550 m).
- Single-mode: yellow jacket, OS1/OS2
- Multimode: orange/aqua jacket, OM1–OM5
- Longer distance = single-mode required
Memory trick: Single strand, single mode, sends signals SUPER far.