66. Let’s move to coax. Please explain some of its specifics related to networking. For example, I’ve heard of thin and thick coax. What do these mean?

In computer networking, coax is described as either thick or thin. Thick coax is used as the medium for “Thick Ethernet,” which is known as IEEE 802.3 10BASE5. Depending on the manufacturer, the cable’s outer diameter ranges from 0.375 inch to 0.405 inch (0.96 cm to 1.04 cm). Thick coax resembles a garden hose and is known as “Etherhose” in slang terms in the industry. It has a designation of RG-8 with 50 Ω impedance. This medium is expensive and outdated; networks based on it today are usually inherited, not installed. Thin coax is used as the medium for “Thin Ethernet,” which is known as IEEE 802.3 10BASE2. Its outer diameter ranges from 0.175 inch to 0.195 inch (0.448 cm to 0.5 cm). Thin coax is designated RG-58 and it too has 50 Ω impedance. Although quite popular in the 1980s and early 1990s, thin coax has fallen out of favor for UTP, and as is the case with Thick Ethernet, a Thin Ethernet is more likely to be inherited and not installed today.

In analog coaxial networks, such as residential cable television networks, cable such as RG-9 may be used, which typically has a greater impedance factor (62 Ω to 76 Ω) and differing electrical characteristics from those of RG-8. Similarly, RG-59 with an impedance of 75 Ω is used for home TV cable, but it looks almost the same as RG-58. It is easy to become confused because the cables within each genre look practically the same. In fact, use of the wrong type of cable is one of the most frequent causes of insidious network failure. Therefore, because not all coaxial cables are electrically the same, you must be careful to select the right one for the types of network equipment being considered for use.