The Network Time Protocol Version 4 (NTPv4) Extension Fields

The information below is for an old version of the document
Document Type Expired Internet-Draft (ntp WG)
Authors Tal Mizrahi  , Danny Mayer 
Last updated 2015-06-27 (latest revision 2014-12-24)
Stream Internet Engineering Task Force (IETF)
Expired & archived
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


The Network Time Protocol Version 4 (NTPv4) defines the optional usage of extension fields. An extension field, defined in RFC5905, is an optional field that resides at the end of the NTP header, and can be used to add optional capabilities or additional information that is not conveyed in the standard NTP header. This document updates RFC5905 by clarifying some points regarding NTP extension fields and their usage with Message Authentication Codes (MAC).


Tal Mizrahi (
Danny Mayer (

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)