CCNA Network Infrastructure and Connectivity Practice Question
Which TWO statements accurately describe characteristics of copper and fiber optic cabling used in modern Ethernet networks?
⚠ Common exam trap
Cisco often tests the distinction between multi-mode and single-mode fiber transmitters, where candidates mistakenly associate laser-based transmitters with multi-mode fiber instead of correctly identifying them with single-mode fiber's long-distance, narrow-core design.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Fiber optic cables are immune to electromagnetic interference (EMI).
Fiber optic cables transmit data as light pulses through glass or plastic cores, which are completely unaffected by electromagnetic interference (EMI), unlike copper cables that rely on electrical signals and are susceptible to EMI. Option D is correct because single-mode fiber uses a narrow core (typically 9 microns) and laser transmitters to support long-distance transmission (up to tens of kilometers) with low signal loss. Option A is wrong because copper UTP cables are limited to 100 meters without a repeater, not 500 meters. Option C is wrong because multi-mode fiber typically uses LED or VCSEL transmitters for short-range communication, while laser-based transmitters are used with single-mode fiber. Option E is wrong because fiber optic cabling is generally more expensive per meter than copper cabling, though installation and equipment costs may differ.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Copper UTP cables can reliably transmit data up to 500 meters without a repeater.
Why it's wrong here
UTP cabling is limited by attenuation and the Ethernet round-trip delay constraint: over 100 meters, signal strength drops and bit error rates climb beyond acceptable limits. The 802.3 standards specify a 100-meter maximum segment length for twisted-pair copper (e.g., 100BASE-T and 1000BASE-T), so 500 meters without a repeater is not possible.
- ✓
Fiber optic cables are immune to electromagnetic interference (EMI).
Why this is correct
Fiber optic cables transmit data as pulses of light through a glass or plastic core, so they are completely unaffected by electromagnetic interference, radio-frequency interference, or electrical crosstalk from nearby power cables and machinery. This immunity makes single-mode and multi-mode fiber the preferred medium in industrial environments, data centers, and other settings where electrical noise would corrupt copper signals.
- ✗
Multi-mode fiber typically uses laser-based transmitters for short-range communication.
Why it's wrong here
Multi-mode fiber is designed for short-range links and typically uses LED or VCSEL light sources, not the high-power, long-wavelength lasers reserved for single-mode fiber. VCSELs are technically laser diodes, but they emit lower-power, divergent light matched to the larger multi-mode core; calling all transmitters 'laser-based' blurs the distinction that multi-mode avoids expensive single-mode lasers, so the statement is incorrect.
- ✓
Single-mode fiber is designed for long-distance transmission with a narrow core.
Why this is correct
Single-mode fiber has an extremely narrow core, about 9 microns in diameter, which permits only a single propagation mode of light to travel in a straight path. Because there is no modal dispersion between multiple reflection paths, light can travel for many kilometers—often 40 km or more—before needing regeneration, making it ideal for long-haul and high-bandwidth applications.
- ✗
Fiber optic cabling is generally less expensive per meter than copper cabling.
Why it's wrong here
Although bare fiber strands can be inexpensive, a complete fiber optic link requires optical transceivers, polishing, splicing, and specialized termination, making it costlier than copper on a per-meter, end-to-end basis. Copper UTP cables and their standard RJ45 connectors and PHY chips are mass-produced and cheap, so fiber is not generally less expensive per meter than copper in practice.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓Fiber optic cables are immune to electromagnetic interference (EMI).Correct answer▾
Why this is correct
Fiber optic cables transmit data as pulses of light through a glass or plastic core, so they are completely unaffected by electromagnetic interference, radio-frequency interference, or electrical crosstalk from nearby power cables and machinery. This immunity makes single-mode and multi-mode fiber the preferred medium in industrial environments, data centers, and other settings where electrical noise would corrupt copper signals.
✗Copper UTP cables can reliably transmit data up to 500 meters without a repeater.Wrong answer — click to see why▾
Why this is wrong here
Copper UTP cables are limited to 100 meters for Ethernet due to signal attenuation and crosstalk, not 500 meters. Exceeding this distance requires a repeater or switch.
Why candidates choose this
Students may confuse the 100-meter limit with the maximum distance for other technologies like telephone lines or mistakenly think UTP can reach longer distances without repeaters.
✗Multi-mode fiber typically uses laser-based transmitters for short-range communication.Wrong answer — click to see why▾
Why this is wrong here
Multi-mode fiber typically uses LEDs or VCSELs (Vertical-Cavity Surface-Emitting Lasers) for short-range communication, not high-power lasers. High-power lasers are used in single-mode fiber for long distances.
Why candidates choose this
The term 'laser' in VCSEL may lead students to think multi-mode uses lasers, but VCSELs are low-power and distinct from the lasers used in single-mode transceivers.
✗Fiber optic cabling is generally less expensive per meter than copper cabling.Wrong answer — click to see why▾
Why this is wrong here
Fiber optic cabling and its associated transceivers are generally more expensive per meter than copper cabling. Copper is cheaper due to widespread manufacturing and simpler termination.
Why candidates choose this
Students might think fiber is cheaper because it can transmit over longer distances without repeaters, but the initial cost of fiber and optics is higher than copper.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Go deeper
Related to this question
Learn chapter
Ethernet Standards
Key term
Ethernet
Ethernet is a wired networking technology that connects devices like computers, printers, and servers to each other and to the internet using cables.
Key term
UTP
Unshielded Twisted Pair (UTP) is a copper cabling type with pairs of twisted wires and no shielding, used for Ethernet networks.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.