NTP

Network Time Protocol

NTP and rdate are used to synchronize time. It is a network time protocol designed to maintain accurate time over the internet. Time is adjusted according to radio or atomic clocks, and can be synchronized down to milliseconds (1/1000 second). NTP uses

UDP 123 as default port.

Stratum hierarchy:

Stratum 0 refers to GPS, cesium atomic clocks, and other time reference equipment

Stratum 1 servers synchronize time directly from GPS or cesium atomic clocks

Stratum 2 tree structure

Synchronizes from Stratum 2
Stratum 3 servers that receive synchronization act as peers to synchronize other operational servers, reducing the load on Stratum 1 servers

NTP Protocol Usages

Korea NTP Server

NTP LINUX

NTP Tools

Where does my computer get the time from? – Tony Finch

This week I was in Rotterdam for a RIPE meeting. On Friday morning I gave a lightning talk called where does my computer get the time from? The RIPE meeting website has a copy of my slides and a video of the talk; this is a blogified low-res version of the slides with a rough and inexact transcript.