Network Time Protocol Version 4: Protocol and Algorithms Specification
RFC 5905, “Network Time Protocol Version 4: Protocol and Algorithms Specification”, is a Proposed Standard document published in June 2010 by D. Mills, J. Martin, J. Burbank, W. Kasch. It obsoletes RFC 1305, RFC 4330. It has since been updated by RFC 7822, RFC 8573, RFC 9109, RFC 9748, RFC 9769. The canonical text is published by the RFC Editor.
Abstract
The Network Time Protocol (NTP) is widely used to synchronize computer clocks in the Internet. This document describes NTP version 4 (NTPv4), which is backwards compatible with NTP version 3 (NTPv3), described in RFC 1305, as well as previous versions of the protocol. NTPv4 includes a modified protocol header to accommodate the Internet Protocol version 6 address family. NTPv4 includes fundamental improvements in the mitigation and discipline algorithms that extend the potential accuracy to the tens of microseconds with modern workstations and fast LANs. It includes a dynamic server discovery scheme, so that in many cases, specific server configuration is not required. It corrects certain errors in the NTPv3 design and implementation and includes an optional extension mechanism.
What “Proposed Standard” means
An entry-level standards-track specification: stable, peer-reviewed and a solid basis for implementation, though it may still evolve before becoming an Internet Standard.
The canonical text of RFC 5905 is hosted at rfc-editor.org. Available in TXT,HTML.
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