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200-301 · Question #838

What is the difference between 1000BASE-LX/LH and 1000BASE-ZX interfaces?

The correct answer is C. 1000BASE-LX/LH is supported on links up to 10km, and 1000BASE-ZX operates over links up to. The primary difference between 1000BASE-LX/LH and 1000BASE-ZX interfaces lies in their supported link distances, with LX/LH supporting up to 10km and ZX supporting significantly longer distances up to 70km or more over single-mode fiber.

Submitted by certguy· Mar 5, 2026Network Fundamentals

Question

What is the difference between 1000BASE-LX/LH and 1000BASE-ZX interfaces?

Options

  • A1000BASE-ZX is supported on links up to 1000km, and 1000BASE-LX/LH operates over links up
  • B1000BASE-LX/LH interoperates with multimode and single-mode fiber, and 10008ASE-ZX needs
  • C1000BASE-LX/LH is supported on links up to 10km, and 1000BASE-ZX operates over links up to
  • D1000BASE-ZX interoperates with dual-rate 100M/1G 10Km SFP over multimode fiber, and

How the community answered

(44 responses)
  • A
    5% (2)
  • B
    2% (1)
  • C
    86% (38)
  • D
    7% (3)

Why each option

The primary difference between 1000BASE-LX/LH and 1000BASE-ZX interfaces lies in their supported link distances, with LX/LH supporting up to 10km and ZX supporting significantly longer distances up to 70km or more over single-mode fiber.

A1000BASE-ZX is supported on links up to 1000km, and 1000BASE-LX/LH operates over links up

1000BASE-ZX does not support links up to 1000km; its typical maximum reach is around 70-100km.

B1000BASE-LX/LH interoperates with multimode and single-mode fiber, and 10008ASE-ZX needs

While 1000BASE-LX/LH can operate with multimode fiber using a mode-conditioning patch cable, this statement does not capture the primary distance difference that distinguishes these standards.

C1000BASE-LX/LH is supported on links up to 10km, and 1000BASE-ZX operates over links up toCorrect

1000BASE-LX/LH transceivers are designed for single-mode fiber links up to 10 km, while 1000BASE-ZX transceivers are extended-reach optics designed for single-mode fiber links up to 70 km or more.

D1000BASE-ZX interoperates with dual-rate 100M/1G 10Km SFP over multimode fiber, and

This choice describes specific SFP features (dual-rate) and fiber types that do not define the fundamental difference in typical reach between 1000BASE-LX/LH and 1000BASE-ZX.

Concept tested: Gigabit Ethernet fiber optic standards

Source: https://www.cisco.com/c/en/us/products/collateral/modules/gigabit-ethernet-sfp-modules/product_data_sheet0900aecd80337ffb.html

Topics

#1000BASE-LX/LH#1000BASE-ZX#Gigabit Ethernet#Fiber optic media

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