Which fiber type is typically used for short-range communications due to its larger core size?

• A. Multi-mode Fiber
• B. Single-mode Fiber
• C. ST Connector
• D. FTPS

Answer: (A)

The main idea here is how the core size of an optical fiber affects where it’s most useful. A larger core allows light to travel in many different paths (modes), which makes it easy to couple light into the fiber and to use inexpensive light sources like LEDs. This multimode behavior works well over short distances, such as inside a building or on a campus, because the different paths cause modal dispersion that accumulates with distance and limits how far the signal can go reliably. So, a fiber with a larger core is typically chosen for short-range networks.

In contrast, single-mode fiber has a very small core, so light travels in essentially a single path. That minimizes dispersion and lets signals travel much farther with high fidelity, which is why it’s preferred for long-haul links. The other options aren’t fiber types: a connector type describes how fibers are joined, not the fiber itself, and a protocol like FTPS relates to data security, not transmission media.