Watchdog Timers Watchdog timers are often used both in hardware and software to detect errors.
Software is required to periodically probe some timer.
If the system fails to do this at some prearranged frequency, an alarm is raised. In a distributed system, this is a very useful technique. Many systems rely on probes not simply to test the liveness of a service, but to make fault detection more timely so that use of an alternate can be chosen more quickly.