Cisco Certified Network Associate (CCNA) Practice Exam

Which two Ethernet fiber-optic modes can support distances greater than 550 meters?

1. 1000BASE-CX and 1000BASE-SX

2. 100BASE-FX and 1000BASE-LX

3. 1000BASE-LX and 1000BASE-ZX

4. 100BASE-FX and 1000BASE-ZX

The correct answer is: 1000BASE-LX and 1000BASE-ZX

The correct answer highlights the two Ethernet fiber-optic modes capable of supporting distances greater than 550 meters. 1000BASE-LX is designed for long-range data transmission over multimode and single-mode fiber. Specifically, it can operate at distances up to 550 meters on multimode fiber but significantly extends that range on single-mode fiber, allowing for several kilometers of coverage. 1000BASE-ZX is even more suited for long distances, as it is designed to operate over single-mode fiber and can reach distances up to 70 km (about 43 miles). This makes both 1000BASE-LX and 1000BASE-ZX optimal choices for applications requiring extensive distance capabilities beyond what multimode fiber supports. The other options include combinations of Ethernet modes that either do not achieve the 550-meter threshold or are limited to less than that range when using multimode fiber. For instance, 100BASE-FX is an older standard primarily used for short to medium distances, typically up to 400 meters on multimode fiber, and does not support distances greater than 550 meters.