Coaxial Cable and Where It Still Lives

Coaxial cable, or coax, is an older copper cable type built very differently from twisted pair. It has a single solid copper core surrounded by layers, all sharing one central axis — which is where the name comes from. Although twisted pair replaced coax in most networks, coax is far from dead. It still carries internet and TV into millions of homes, so the exam expects you to recognize it.

Coax has four layers around a common center:

• Center conductor — a solid copper wire carrying the signal.
• Dielectric insulator — plastic separating core from shield.
• Metallic shield — foil or braid blocking interference.
• Outer jacket — protective plastic cover.

This shielded design makes coax very resistant to EMI, letting it run long distances with little signal loss.