RFC 1129: Internet Time Synchronization: the Network Time Protocol
RFC 1129: Internet Time Synchronization: the Network Time Protocol, written by David L. Mills in 1989, describes the Network Time Protocol (NTP) which is designed to distribute time information in a large, diverse internet system operating at speeds from mundane to lightwave. The architectures, algorithms, and protocols which have evolved to NTP over several years of implementation and refinement are described in this paper. The synchronization subnet which has been in regular operation in the Internet for the last several years is described along with performance data which shows that timekeeping accuracy throughout most portions of the Internet can be ordinarily maintained to within a few tens of milliseconds, even in cases of failure or disruption of clocks, time servers or networks.