This document describes the Simple Network Time Protocol (SNTP)
Version 4, which is a subset of the Network Time Protocol (NTP)
used to synchronize computer clocks in the Internet. SNTP can be
used when the ultimate performance of the full NTP implementation
described in RFC-1305 is not needed or justified. SNTP Version 4
clarifies certain design features of NTP which allow operation in a
simple, stateless remote-procedure call (RPC) mode with accuracy
and reliability expectations similar to the UDP/TIME protocol
described in RFC-868.
The only significant protocol change in SNTP Version 4 is a
modified header interpretation to accommodate Internet Protocol
Version 6 (IPv6) (RFC-1883) and OSI (RFC-1629) addressing.
However, SNTP Version 4 includes an anycast mode and a public-key
based authentication scheme designed specifically for broadcast and
anycast applications. The authentication scheme extension is
described in another RFC. Until a definitive specification is
published, these extensions should be considered provisional. In
addition, this memo introduces the kiss-o'-death message, which can
be used by servers to suppress client requests as circumstances
Working Group Summary
An IETF WG for NTP is about to be chartered, as a follow-up to a
BOF that was held at the November, 2004 IETF. At the BOF, it was
decided that this document should be pubished as is (as an
Informational RFC), and that the document would be used as a basis
for developing a standards track version of NTP in a WG (in the
process of being formed).
This document has been reviewed for the IESG by Thomas Narten, and
there are multiple implementations.
This RFC is not a candidate for any level of Internet Standard. The
IETF disclaims any knowledge of the fitness of this RFC for any
purpose and in particular notes that the decision to publish is not
based on IETF review for such things as security, congestion
control, or inappropriate interaction with deployed protocols. The
RFC Editor has chosen to publish this document at its discretion.
Readers of this document should exercise caution in evaluating its
value for implementation and deployment. See RFC 3932 for more
The reader should be aware that the IETF has formed an NTP Working
Group to develop a Standards Track version of NTP version 4. This
document will serve as input to that effort.