This paper describes a series of experiments involving over 100,000 hosts of the Internet system and located in the U.S., Europe and the Pacific. The experiments are designed to evaluate the availability, accuracy and reliability of international standard time distribution using the Internet and the Network Time Protocol (NTP), which has been designated an Internet Standard protocol. NTP is designed specifically for use in a large, diverse internet system operating at speeds from mundane to lightwave. In NTP a distributed subnet of time servers operating in a self-organizing, hierarchical, master-slave configuration exchange precision timestamps in order to synchronize host clocks to each other and national time standards via wire or radio. The experiments are designed to locate Internet hosts and gateways that provide time by one of three time distribution protocols and evaluate the accuracy of their indications. For those hosts that support NTP, the experiments determine the distribu..