N10-009 Network Implementation Practice Question
A network administrator needs to upgrade the backbone link between two switches to fiber optic to eliminate electromagnetic interference. The distance between the switches is 350 meters. Which transceiver type should be used?
⚠ Common exam trap
The N10-009 exam often tests the distance limitations of fiber transceivers, and the trap here is that candidates might choose 1000BASE-LX because they assume 'longer distance is always better,' overlooking that 1000BASE-SX is the correct, cost-effective choice for the given 350-meter range over multimode fiber.
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
1000BASE-SX (option A) is correct because it supports distances up to 550 meters over multimode fiber (MMF) at 850 nm wavelength, making it suitable for the 350-meter backbone link. It is designed to eliminate electromagnetic interference (EMI) by using fiber optic cabling, and the distance falls within its maximum reach for common multimode fiber types like OM2 or OM3.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
1000BASE-SX
Why this is correct
1000BASE-SX is the optimal choice for upgrading a backbone link to fiber optic over a 350-meter distance. This standard utilizes multi-mode fiber, which is cost-effective for medium-range applications and perfectly supports distances up to 550 meters. Its use of shorter wavelength lasers (850 nm) makes it suitable for the specified requirement, providing reliable gigabit connectivity while effectively avoiding electromagnetic interference.
- ✗
1000BASE-LX
Why it's wrong here
While 1000BASE-LX does utilize fiber optic cabling and could technically cover 350 meters, it is primarily designed for much longer distances, up to 10 kilometers, typically over single-mode fiber. Employing single-mode fiber and its associated transceivers for a relatively short 350-meter link is significantly more expensive than using multi-mode fiber with 1000BASE-SX. Therefore, 1000BASE-LX represents a less cost-effective and over-engineered solution for the specified distance.
When this WOULD be correct
A network administrator needs to connect two switches 2 km apart using fiber optic cable. Which transceiver type should be used? (1000BASE-LX supports longer distances over single-mode fiber.)
- ✗
1000BASE-CX
Why it's wrong here
1000BASE-CX is unsuitable for this upgrade because it relies on shielded copper twinaxial cabling, not fiber optic. This standard is designed for extremely short-distance connections, typically limited to a maximum of 25 meters, making it entirely inadequate for a 350-meter backbone link. Furthermore, as a copper solution, it would not provide the desired immunity to electromagnetic interference that a fiber optic upgrade offers.
When this WOULD be correct
This option would be correct for a short-distance, high-speed backbone link within a data center or server room (e.g., connecting switches in the same rack) where low cost and low latency are needed, and fiber is not required.
- ✗
1000BASE-T
Why it's wrong here
1000BASE-T operates over unshielded twisted-pair copper cabling, specifically Cat5e or Cat6, and is therefore not a fiber optic solution. While it supports distances up to 100 meters, it falls significantly short of the 350-meter requirement for the backbone link. Moreover, copper cabling remains susceptible to electromagnetic interference, which a fiber upgrade aims to mitigate, making this option inappropriate.
When this WOULD be correct
1000BASE-T would be correct if the question asked for a Gigabit Ethernet connection over existing copper infrastructure within 100 meters, without concerns about EMI, such as connecting a server to a switch in the same rack.
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 N10-009 exam frequently reuses these exact scenarios with slightly different constraints.
✓1000BASE-SXCorrect answer▾
Why this is correct
1000BASE-SX is the optimal choice for upgrading a backbone link to fiber optic over a 350-meter distance. This standard utilizes multi-mode fiber, which is cost-effective for medium-range applications and perfectly supports distances up to 550 meters. Its use of shorter wavelength lasers (850 nm) makes it suitable for the specified requirement, providing reliable gigabit connectivity while effectively avoiding electromagnetic interference.
✗1000BASE-LXWrong answer — click to see why▾
Why this is wrong here
1000BASE-LX is designed for single-mode fiber with distances up to 5 km, but the question specifies a distance of 350 meters over multimode fiber, where 1000BASE-SX is the appropriate choice for cost-effective short-range links.
★ When this WOULD be the correct answer
A network administrator needs to connect two switches 2 km apart using fiber optic cable. Which transceiver type should be used? (1000BASE-LX supports longer distances over single-mode fiber.)
Why candidates choose this
Candidates may confuse LX as a general long-range option without considering the specific distance (350m) and fiber type (multimode) in the question, assuming LX is always better.
✗1000BASE-CXWrong answer — click to see why▾
Why this is wrong here
1000BASE-CX uses copper twinaxial cable, not fiber optic, and is limited to distances up to 25 meters, far short of the required 350 meters.
★ When this WOULD be the correct answer
This option would be correct for a short-distance, high-speed backbone link within a data center or server room (e.g., connecting switches in the same rack) where low cost and low latency are needed, and fiber is not required.
Why candidates choose this
Candidates may confuse 'CX' with fiber or think it supports longer distances due to the 'C' prefix, or they may overlook the distance limitation and focus only on the need for a backbone link.
✗1000BASE-TWrong answer — click to see why▾
Why this is wrong here
1000BASE-T uses twisted-pair copper cabling (Cat5e or higher) and is susceptible to electromagnetic interference, which the question explicitly requires eliminating. It also has a maximum distance of 100 meters, far less than the 350 meters needed.
★ When this WOULD be the correct answer
1000BASE-T would be correct if the question asked for a Gigabit Ethernet connection over existing copper infrastructure within 100 meters, without concerns about EMI, such as connecting a server to a switch in the same rack.
Why candidates choose this
Candidates may default to 1000BASE-T because it is the most common Gigabit Ethernet standard for copper cabling, and they might overlook the distance and EMI requirements in the question.
Analysis generated from the official N10-009blueprint 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
Physical Network Infrastructure
Key term
Multimode fiber
A type of optical fiber that carries multiple light signals simultaneously over short to medium distances, commonly used in local area networks and data centers.
Key term
Transceiver
A transceiver is a device that both transmits and receives signals, combining a transmitter and a receiver into a single unit for communication over a network medium.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This N10-009 practice question is part of Courseiva's free CompTIA 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 N10-009 exam.