Cable television networks provide analog and digital television broadcasts as well as Internet connectivity to subscribers. Exposure to the elements and gradual wear reduce the performance of the analog portion of the hybrid fiber and coaxial network. Network monitoring capabilities are minimal and network failures require the rapid deployment of a cable technician. Our research shows that status information returned from cable modems can be used to give a measure of network health and provide a means for fault detection. Techniques detecting behavior deviations of individual modems have been developed and evaluated. The topology of the network then provides constraints which are used to determine the part of the network where the fault has occurred that manifests itself as a behavior deviation of particular cable modem(s).