Which network cable bounces light off protective cladding?

N10-009 By islever Editorial Last updated Sep 3, 2026

Short answer

D Multimode

Question

Which of the following network cables involves bouncing light off of protective cladding?

Twinaxial
Coaxial
Single-mode
Multimode Correct Answer

Key Takeaways

The question tests fiber-optic propagation modes: multimode's larger core lets light rays reflect off the cladding, while single-mode's tiny core keeps the ray centered with no bouncing.

In CompTIA Network+ N10-009, the cable that bounces light off cladding is multimode fiber. Community explanations confirm that single-mode fiber carries light in a straight line, while multimode fiber uses total internal reflection off the cladding.

Common mistake: The most common wrong answer is C, single-mode, likely because test takers know that both fiber types have cladding. However, single-mode fiber minimizes reflection; it is multimode fiber that causes light to bounce off the cladding along multiple paths.

Expert Analysis

Why the Answer Is Correct

Multimode fiber (option D) has a core of 50 or 62.5 µm, and light waves travel at multiple angles. Each time a light ray hits the core-cladding boundary, total internal reflection makes it bounce back into the core; this cladding boundary is the 'protective cladding' the question refers to. Comment [1] explains exactly this: multimode allows light signals to travel in multiple paths and bounce off the cladding. Comment [4] reinforces that single-mode was designed so data travels without bouncing off the walls, which implies bouncing is the multimode behavior.

Why the Other Options Are Wrong

Twinaxial and coaxial cables are electrical copper cables, so neither carries light or uses cladding in an optical sense. Coaxial cable uses a dielectric insulator and shielding, not optical cladding. Single-mode fiber does have cladding around its ~9 µm core, but its core is so small that the light propagates as a single mode straight along the center, not bouncing. Comment [3] claims single-mode light bounces off cladding 'in a straight line,' which is self-contradictory and physically incorrect.

Community Comment Notes

The vote distribution shows D leading with 78% versus C at 22%, but there is residual confusion. The highest-rated comment [1] gives a clear, correct explanation for multimode and explicitly contrasts the small core of single-mode. Comment [4] further clarifies that single-mode avoids bouncing to maintain high transfer speeds. Comment [3], although it picked C, actually proves the common mistake by mislabeling the mechanism; note that 'cladding' exists in both fiber types, but only multimode is characterized by light bouncing off it.

Official Reference

These links open the official vendor documentation in a new tab.

Exam Strategy

When an item mentions 'bouncing light off cladding,' think of total internal reflection in multimode fiber. Remember that single-mode means one straight light path, while multimode means many reflecting paths—so you can quickly eliminate single-mode on fiber questions that emphasize bouncing.

Community Votes

78%

22%

78% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 4 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 4

FrozenCarrot 👍 3 Answered D

The correct answer is D. Multimode. Explanation: Multimode fiber optic cables use a larger core (typically 50 or 62.5 microns) that allows light signals to travel in multiple paths (modes). These signals bounce off the protective cladding (due to total internal reflection) as they propagate, which is a defining characteristic of multimode fibers. In contrast, single-mode fiber (C) has a much smaller core (9 microns) and uses a single, direct path for light with minimal reflection. Twinaxial (A) and Coaxial (B) cables transmit electrical signals, not light, and are unrelated to fiber optics. Thus, multimode fiber explicitly relies on bouncing light off the cladding to transmit data.
chupapi_001 👍 3 Answered D

The correct answer is D. Multimode
HeatSquad77 👍 2 Answered C

C. Single-mode. In a single-mode fiber optic cable, light travels through a core with a very small diameter, and it bounces off the cladding (the protective layer surrounding the core) in a straight line. This design allows the light to travel long distances with minimal signal loss.
penguin4121 👍 1 Answered D

SINGLE MODE!!! It has the peculiarity that inside of its core, data travels WITHOUT bouncing off of its walls which allows and maintains higher transfer speeds

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