Which medium is commonly used for legacy industrial networks and uses coaxial conductors?

• A. Two-wire
• B. Ethernet
• C. Shielded
• D. Coaxial

Answer: (D)

Coaxial cable is the medium that fits this description. It uses a central conductor with surrounding insulation and shielding inside a protective jacket, a setup that provides good resistance to electrical interference and allows longer runs in bus-style layouts. This made coaxial cables a common choice for legacy industrial networks and early Ethernet variants that relied on coax and terminators. As technology evolved toward higher bandwidth and more flexible topologies, twisted-pair and fiber became the go-to options, so coax remains associated with older, legacy systems. Other choices describe the protocol or a characteristic rather than the actual transmission medium.