- A
SFP transceivers are permanently installed on the switch motherboard and cannot be replaced.
Why wrong: SFP transceivers are hot-swappable and can be inserted or removed without powering down the switch, allowing easy media changes.
- B
1000BASE-SX SFP transceivers are designed for multimode fiber and typically support distances up to 550 meters.
1000BASE-SX uses multimode fiber with a 850 nm wavelength and supports distances up to 550 m (depending on fiber grade).
- C
Multimode fiber typically uses laser-based transmitters for long-distance transmission.
Why wrong: Multimode fiber uses LED or VCSEL (Vertical-Cavity Surface-Emitting Laser) sources that are less expensive but limited to shorter distances.
- D
Single-mode fiber (SMF) with 1000BASE-LX SFP transceivers can support distances up to 5 km.
1000BASE-LX SFP transceivers are designed for single-mode fiber and support a maximum distance of 5 km according to IEEE 802.3z. Vendor-specific 'LX/LH' transceivers may extend this to 10 km, but the CCNA exam focuses on standard specifications.
- E
Single-mode fiber has a larger core diameter than multimode fiber, allowing longer distances.
Why wrong: Single-mode fiber has a much smaller core (about 9 microns) compared to multimode (50 or 62.5 microns). The smaller core reduces modal dispersion, enabling longer distances.
Quick Answer
The correct statements are that single-mode fiber (SMF) with 1000BASE-LX SFP transceivers can support distances up to 5 km, and 1000BASE-SX SFP transceivers on 50/125 µm multimode fiber (MMF) support up to 550 meters. This is because SFP transceiver types are wavelength-specific: 1000BASE-SX uses short-wavelength 850 nm lasers for MMF, while 1000BASE-LX uses long-wavelength 1310 nm lasers for SMF, where the smaller core diameter (8-10 µm) minimizes modal dispersion and enables longer fiber optic distances. On the CCNA 200-301 v2 exam, this tests your understanding of physical layer standards and the relationship between SFP modules, fiber types, and maximum reach—a common trap is confusing LX with 10 km vendor extensions or assuming SFPs are permanently installed. Remember the memory tip: “SX for Short reach on Multi-mode (850 nm), LX for Long reach on Single-mode (1310 nm, up to 5 km).”
CCNA Network Infrastructure and Connectivity Practice Question
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 about SFP transceivers and fiber optic cabling are correct?
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
1000BASE-SX SFP transceivers are designed for multimode fiber and typically support distances up to 550 meters.
Option B is correct because 1000BASE-SX SFP transceivers are designed for multimode fiber (MMF) and use short-wavelength lasers (850 nm). Over 50/125 µm MMF, they support up to 550 meters. Option D is correct because 1000BASE-LX SFP transceivers are designed for single-mode fiber (SMF) and support distances up to 5 km according to the IEEE 802.3 standard (not 10 km, which is typically a vendor-specific LH extension). Option A is false because SFPs are hot-swappable pluggable modules, not permanently installed. Option C is false because multimode fiber typically uses LED or VCSEL transmitters for short distances, not lasers for long-haul. Option E is false because single-mode fiber has a smaller core diameter (8-10 µm) than multimode fiber (50-62.5 µm), which reduces modal dispersion and allows longer distances.
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.
- ✗
SFP transceivers are permanently installed on the switch motherboard and cannot be replaced.
Why it's wrong here
SFP transceivers are hot-swappable and can be inserted or removed without powering down the switch, allowing easy media changes.
- ✓
1000BASE-SX SFP transceivers are designed for multimode fiber and typically support distances up to 550 meters.
Why this is correct
1000BASE-SX uses multimode fiber with a 850 nm wavelength and supports distances up to 550 m (depending on fiber grade).
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Multimode fiber typically uses laser-based transmitters for long-distance transmission.
Why it's wrong here
Multimode fiber uses LED or VCSEL (Vertical-Cavity Surface-Emitting Laser) sources that are less expensive but limited to shorter distances.
- ✓
Single-mode fiber (SMF) with 1000BASE-LX SFP transceivers can support distances up to 5 km.
Why this is correct
1000BASE-LX SFP transceivers are designed for single-mode fiber and support a maximum distance of 5 km according to IEEE 802.3z. Vendor-specific 'LX/LH' transceivers may extend this to 10 km, but the CCNA exam focuses on standard specifications.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Single-mode fiber has a larger core diameter than multimode fiber, allowing longer distances.
Why it's wrong here
Single-mode fiber has a much smaller core (about 9 microns) compared to multimode (50 or 62.5 microns). The smaller core reduces modal dispersion, enabling longer distances.
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.
✓1000BASE-SX SFP transceivers are designed for multimode fiber and typically support distances up to 550 meters.Correct answer▾
Why this is correct
1000BASE-SX uses multimode fiber with a 850 nm wavelength and supports distances up to 550 m (depending on fiber grade).
✗SFP transceivers are permanently installed on the switch motherboard and cannot be replaced.Wrong answer — click to see why▾
Why this is wrong here
This statement is false because SFP slots are designed for modular, replaceable transceivers.
✗Multimode fiber typically uses laser-based transmitters for long-distance transmission.Wrong answer — click to see why▾
Why this is wrong here
Laser transmitters are used in single-mode fiber for longer distances; multimode uses LED/VCSEL.
✗Single-mode fiber has a larger core diameter than multimode fiber, allowing longer distances.Wrong answer — click to see why▾
Why this is wrong here
Single-mode fiber has a smaller core, not larger. The smaller core reduces dispersion and allows longer reach.
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 misconception that multimode fiber always uses lasers for long distances, when in fact multimode fiber is optimized for shorter runs with LED or VCSEL sources, while single-mode fiber uses lasers for extended reach.
Detailed technical explanation
How to think about this question
Under the hood, 1000BASE-SX uses 850 nm wavelength and relies on the modal bandwidth of MMF, which limits distance due to modal dispersion. In contrast, 1000BASE-LX uses 1310 nm laser transmitters and can operate over both single-mode fiber (up to 10 km) and multimode fiber (with a mode-conditioning patch cable to avoid differential mode delay). Real-world deployments often mix SX and LX transceivers based on distance requirements, and using LX on MMF without the proper patch cable can cause excessive bit errors.
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: 1000BASE-SX SFP transceivers are designed for multimode fiber and typically support distances up to 550 meters. — Option B is correct because 1000BASE-SX SFP transceivers are designed for multimode fiber (MMF) and use short-wavelength lasers (850 nm). Over 50/125 µm MMF, they support up to 550 meters. Option D is correct because 1000BASE-LX SFP transceivers are designed for single-mode fiber (SMF) and support distances up to 5 km according to the IEEE 802.3 standard (not 10 km, which is typically a vendor-specific LH extension). Option A is false because SFPs are hot-swappable pluggable modules, not permanently installed. Option C is false because multimode fiber typically uses LED or VCSEL transmitters for short distances, not lasers for long-haul. Option E is false because single-mode fiber has a smaller core diameter (8-10 µm) than multimode fiber (50-62.5 µm), which reduces modal dispersion and allows longer distances.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
4 more ways this is tested on 200-301
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Which TWO statements about SFP transceivers and their associated cable types are correct?
medium- A.SFP-10G-SR transceivers require single-mode fiber.
- ✓ B.SFP-10G-LR transceivers use 1310 nm wavelength and can reach up to 10 km over single-mode fiber.
- C.SFP-10G-LR transceivers can only be used with multimode fiber.
- ✓ D.SFP-10G-SR transceivers typically use 850 nm wavelength over multimode fiber.
- E.SFP-10G-LR transceivers support distances up to 40 km over single-mode fiber.
Why B: Option B is correct because the SFP-10G-LR transceiver operates at a 1310 nm wavelength and is designed for single-mode fiber, supporting distances up to 10 km. This is a standard specification defined by IEEE 802.3ae for 10GBASE-LR, making it the accurate description of this transceiver's capabilities.
Variation 2. Which TWO statements about fiber optic cable types and SFP transceivers are correct?
medium- A.Single-mode fiber uses a larger core (typically 62.5/125 µm) and supports longer distances than multimode fiber.
- ✓ B.Multimode fiber is commonly used in campus and data center environments for distances up to several hundred meters.
- C.SFP+ transceivers support data rates up to 1 Gbps and are backward compatible with standard SFP modules.
- ✓ D.Single-mode fiber typically uses laser-based transceivers and can support distances exceeding 10 km.
- E.Fiber optic cables must be run with EMI shielding when deployed in environments with high electromagnetic interference.
Why B: Multimode fiber (MMF) has a larger core (typically 50/125 µm or 62.5/125 µm) and is used for short-reach, cost-effective connections up to a few hundred meters, making option B correct. Single-mode fiber (SMF) uses a much smaller core (~9 µm) and laser-based optics to achieve distances of 10 km or more, so option D is correct. Option A is wrong because it reverses the core size characteristic: SMF has a smaller core, and the given dimensions (62.5/125 µm) refer to multimode. Option C is wrong because SFP+ is a 10 Gbps form factor and is not inherently backward compatible with 1 Gbps SFP modules unless the switch port explicitly supports dual-rate operation. Option E is incorrect because fiber optic cables are inherently immune to electromagnetic interference (EMI) and therefore never require EMI shielding in any environment; the false statement claims they need shielding.
Variation 3. Which TWO statements about fiber optic cables and SFP/SFP+ transceivers are correct?
medium- ✓ A.Single-mode fiber (SMF) uses a smaller core diameter than multimode fiber (MMF).
- B.Multimode fiber supports longer distances than single-mode fiber.
- ✓ C.SFP+ transceivers are commonly used for 10 Gigabit Ethernet connections.
- D.SFP modules support data rates up to 10 Gbps.
- E.Multimode fiber typically has a core diameter of 9 microns.
Why A: Option A is correct because single-mode fiber (SMF) has a core diameter of about 9 microns, which is smaller than multimode fiber (MMF) cores of 50 or 62.5 microns. Option C is correct because SFP+ transceivers are indeed designed for 10 Gigabit Ethernet, supporting data rates up to 10 Gbps. Option B is wrong because multimode fiber is used for shorter distances (up to a few hundred meters) due to higher modal dispersion, while single-mode fiber supports longer distances (tens of kilometers). Option D is wrong because standard SFP modules support up to 1 Gbps, not 10 Gbps; SFP+ modules handle 10 Gbps. Option E is wrong because a 9-micron core is characteristic of single-mode fiber, not multimode fiber.
Variation 4. Which TWO statements about SFP transceivers and interface diagnostics are true?
medium- ✓ A.SFP modules are hot-swappable, meaning they can be inserted or removed without powering off the switch.
- B.Copper 1000BASE-T SFP modules can transmit data up to 10 km over Category 5e cabling.
- ✓ C.The show interfaces transceiver command provides diagnostic details such as temperature, voltage, and optical power levels.
- D.Multi-mode fiber uses a smaller core diameter, about 9 microns, compared to single-mode fiber.
- E.Any SFP transceiver, regardless of vendor, will operate in a Cisco switch by default.
Why A: Option A is correct because SFP (Small Form-factor Pluggable) modules are designed to be hot-swappable, allowing insertion or removal without powering down the switch. This capability is essential for maintaining network uptime during maintenance or upgrades, as the switch can dynamically detect and configure the module without a reboot.
Last reviewed: Jun 11, 2026
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.
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