Cisco Certified Network Associate (CCNA) Practice Exam

Which cabling type and maximum length corresponds to the 1000BASE-LX standard?

1. Short-wavelength laser, 220 m

2. Long-wavelength laser, 10 km (SM)

3. Two strands, multimode, 550 m

4. Copper cabling, 1 km

The correct answer is: Long-wavelength laser, 10 km (SM)

The 1000BASE-LX standard is designed for Gigabit Ethernet over fiber optic cables and uses long-wavelength laser technology. When paired with single-mode fiber (SMF), it can cover distances up to 10 kilometers. This specification is essential for applications that require higher bandwidth over more extended distances, making it suitable for backbone installations in enterprise networks. In this case, the use of long-wavelength lasers allows for more efficient signal transmission over long distances, minimizing signal degradation. Standardizing on the 10 km range enables network engineers to design networks that can easily span considerable distances with reliable performance. This context underscores the capability of 1000BASE-LX to serve diverse networking environments, especially where distance is a critical factor. The specification also highlights the network's ability to accommodate future growth by leveraging single-mode technology to support longer reach compared to other cabling types.