Question 839 of 1,819
Network Infrastructure and ConnectivitymediumMultiple SelectObjective-mapped

Copper Cabling vs Fiber Optic Cabling: Key Differences

This 200-301 practice question tests your understanding of network infrastructure and connectivity. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

Which TWO statements accurately describe characteristics of copper and fiber optic cabling used in modern Ethernet networks?

Quick Answer

The correct answer identifies single-mode fiber as designed for long-distance transmission with a narrow core, and fiber optic cabling as immune to electromagnetic interference. This is because fiber optic cabling transmits data as light pulses through glass or plastic cores, making it completely unaffected by EMI, while copper cabling relies on electrical signals and is susceptible to interference. On the CCNA 200-301 v2 exam, this topic tests your understanding of physical layer media characteristics, often appearing in multiple-choice questions that pair one correct statement about fiber with one about copper. A common trap is confusing multi-mode fiber’s shorter-range LED transmitters with single-mode’s laser-based long-haul capability, or overestimating copper UTP’s distance limit—remember, it’s 100 meters, not 500. For a quick memory tip: think “single-mode, single beam, single long distance” and “copper conducts current, fiber conducts light, no EMI fight.”

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).

Option B is correct because 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.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

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 cables are limited to 100 meters for Ethernet due to signal attenuation.

  • Fiber optic cables are immune to electromagnetic interference (EMI).

    Why this is correct

    Fiber uses light, not electricity, so it is not affected by EMI, making it suitable for noisy environments.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Multi-mode fiber typically uses laser-based transmitters for short-range communication.

    Why it's wrong here

    Multi-mode fiber commonly uses LEDs or VCSELs, not high-power lasers, which are used in single-mode.

  • Single-mode fiber is designed for long-distance transmission with a narrow core.

    Why this is correct

    Single-mode fiber has a small core (about 9 microns) that allows only one mode of light, reducing dispersion and enabling distances over 40 km.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Fiber optic cabling is generally less expensive per meter than copper cabling.

    Why it's wrong here

    Fiber cabling and its associated transceivers are typically more expensive than copper.

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 uses light, not electricity, so it is not affected by EMI, making it suitable for noisy environments.

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?”

Common exam traps

Common exam trap: answer the scenario, not the keyword

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.

Detailed technical explanation

How to think about this question

In single-mode fiber (SMF), the core diameter is about 8–10 microns, allowing only one propagation mode and minimizing modal dispersion, which enables transmission distances exceeding 10 km (e.g., 1000BASE-LX up to 5 km, 10GBASE-LR up to 10 km). Multi-mode fiber (MMF) has a larger core (50 or 62.5 microns) and uses less expensive LED or VCSEL sources, but suffers from modal dispersion that limits reach to around 300–550 meters for 10 Gbps (e.g., OM3/OM4). The immunity to EMI in fiber is due to the absence of conductive material, making it inherently resistant to crosstalk and external noise, a key advantage in industrial or data center environments.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A practitioner preparing for the 200-301 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.

What to study next

Got this wrong? Here's your next step.

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FAQ

Questions learners often ask

What does this 200-301 question test?

Network Infrastructure and Connectivity — This question tests Network Infrastructure and Connectivity — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Fiber optic cables are immune to electromagnetic interference (EMI). — Option B is correct because 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.

What should I do if I get this 200-301 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jun 11, 2026

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