Network Time Protocol (version 2) specification and implementation
David L. Mills · 1989
formal structure and summarizes information useful for its implementation. NTP provides the mechanisms to synchronize time and coordinate time distribution in a large, diverse internet operating at rates from mundane to lightwave. It uses a returnable-time design in which a distributed subnet of time servers operating in a selforganizing, hierarchical master-slave configuration synchronizes logical clocks within the subnet and to national time standards via wire or radio. The servers can also redistribute reference time via local routing algorithms and time daemons. The NTP architectures, algorithms and protocols which have evolved over several years of implementation and refinement are described in this document. The prototype system, which has been in regular operation in the Internet for the last two years, is described in an Appendix along with performance data which shows that timekeeping accuracy throughout most portions of the Internet can be ordinarily