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.