What type of cable is most commonly used in Ethernet LANs?

Twisted pair cable is the most commonly used in Ethernet LANs due to its effectiveness in transmitting data over short to medium distances. This type of cable consists of pairs of insulated copper wires twisted together, which helps reduce electromagnetic interference and crosstalk from adjacent pairs and external sources.

Twisted pair is versatile and comes in various categories, with Category 5e and Category 6 being popular choices for Ethernet networks because they support high data transfer rates and are widely available and cost-effective. The design of twisted pair cabling also allows for easier installation and maintenance, making it a preferred choice for networking professionals.

While coaxial cable and fiber optic cable are used in specific networking scenarios, such as cable television and long-distance communications respectively, they do not match the prevalence and practicality of twisted pair cables in typical Ethernet environments. HDMI cable, on the other hand, is used primarily for audio and video connections rather than networking, which further highlights the appropriateness of twisted pair cable for this application.