Which standard is Gigabit Ethernet over single-mode fiber with a maximum distance of 5 kilometers?

Which standard is Gigabit Ethernet over single-mode fiber with a maximum distance of 5 kilometers?

• A. 1000BASE-LX
• B. 10GBASE-SR
• C. 10GBASE-LR
• D. Cat5e

Answer: (A)

This question hinges on matching data rate, fiber type, and distance. 1000BASE-LX is the Gigabit Ethernet option designed for single-mode fiber and uses a 1310 nm optical carrier, providing about 5 kilometers of reach on standard single-mode fiber. That exactly fits the requirement of Gigabit throughput over single-mode fiber up to 5 km. The other options don’t fit: 10GBASE-SR operates at 10 Gbps over multimode fiber with a much shorter reach, 10GBASE-LR is also 10 Gbps but over single-mode with longer reach (about 10 km), and Cat5e is copper—not fiber. So the best match for the described link is 1000BASE-LX.

This question hinges on matching data rate, fiber type, and distance. 1000BASE-LX is the Gigabit Ethernet option designed for single-mode fiber and uses a 1310 nm optical carrier, providing about 5 kilometers of reach on standard single-mode fiber. That exactly fits the requirement of Gigabit throughput over single-mode fiber up to 5 km. The other options don’t fit: 10GBASE-SR operates at 10 Gbps over multimode fiber with a much shorter reach, 10GBASE-LR is also 10 Gbps but over single-mode with longer reach (about 10 km), and Cat5e is copper—not fiber. So the best match for the described link is 1000BASE-LX.