RFC 1129

Internet Time Synchronization: The Network Time Protocol, October 1989

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D.L. Mills

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DOI:  https://doi.org/10.17487/RFC1129

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This memo describes the Network Time Protocol (NTP) designed to distribute time information in a large, diverse internet system operating at speeds from mundane to lightwave. It uses a returnable- time architecture in which a distributed subnet of time servers operating in a self-organizing, hierarchical, master-slave configuration synchronizes local clocks within the subnet and to national time standards via wire or radio. The servers can also redistribute time information within a network via local routing algorithms and time daemons. 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. This memo describes the Network Time Protocol in RFC-1119.

For the definition of Status, see RFC 2026.

For the definition of Stream, see RFC 8729.

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