Toner and Probe Explained: Cable Tracing Tools for the Network+ Exam
A toner and probe — also called a tone generator and inductive probe , or informally a fox and hound — is the tool you reach for when a cable disappears into a wall at one end and you need to find which of two hundred unlabelled cables in a patch panel is the other end. The toner injects an audible tone onto the cable. The probe finds it by induction, without touching the conductors. It is the answer to one very specific exam question — "how do you identify an unlabelled cable?" — and a genuinely common piece of field work. How It Works The tone generator clips onto or plugs into the cable at one end and injects a low-frequency signal, typically a warbling audio tone. The inductive probe is swept near the suspected cables at the other end. It picks up the electromagnetic field produced by that signal and converts it back to audible sound through a small speaker. The cable carrying the tone is loudest. The word inductive matters: the probe does not need electri...