A method and apparatus for measuring data rates is disclosed. An apparatus that incorporates teachings of the present disclosure may include, for example, a diagnostic system having a Time Domain Reflectometer (TDR) element that submits a signal over a cable and determines from its reflection in the cable a length of the cable and a length of a bridged tap, and a diagnostic element that determines downstream and upstream bit rates for the cable according to the length of the cable and the length of the bridged tap. Additional embodiments are disclosed.