Managing Accurate Date and Time

Avi Alkalay

Brad Knowles - Suggestion to use and NTP's stratum 2 public time servers

Kent Borg - Suggestion to use ntpq instead of ntpdc

Yura Moron - Good explanations on ntpq and ntpdc info

Takeo Nakano -


Mihaly Gyulai -

Philippe Wautelet -

Kemal ├ľkmen -


Revision History
Revision 2005-11-1818 Nov 2005Revised by: Avi
Included link to turkish translation
Revision 2005-10-1212 Oct 2005Revised by: Avi
The Brazil zic file is now external and updated
Revision 2005-05-0303 May 2005Revised by: Avi
Included link to french translation
Revision 1.0.82004-10-29Revised by: Mihaly Gyulai
Hungarian translation, the chorny section and the very first section
Revision 1.0.79 Jul 2004Revised by: avi
Disclaimer near to license, to let people know they can translate without asking permission.Small fixes in some phrases.
Revision 1.0.625 Feb 2004Revised by: avi
Included credits and link to russian translation.
Revision 1.0.505 Jul 2003Revised by: avi
Changed public time servers list URL. Added
Revision 1.0.421 Dec 2002Revised by: avi
Added japanese translation link and credits.
Revision 1.0.324 Aug 2002Revised by: avi
Fixed wrong screen and programlisting widths.
Revision 1.0.204 Aug 2002Revised by: avi
Link to public time servers page.
Revision 1.0.107 May 2002Revised by: avi
Final XML conversion. Files reorganization.
Revision 1.028 Apr 2002Revised by: avi
Finalized image.
Revision 0.827 Apr 2002Revised by: avi
Switched from ntpdc example to ntpq, based on contributions.
Revision 0.8.120 Apr 2002Revised by: avi
Improved graphic. Links to other doc locations.
Revision 0.814 Apr 2002Revised by: avi
Beter tunning of NTP graphic.
Revision 0.7613 Apr 2002Revised by: avi
Inclusion of architecture graphic.
Revision 0.7510 Apr 2002Revised by: avi
Spell checked. Using DocBook XSLT 1.50.
Revision 0.6531 Mar 2002Revised by: avi
Upgraded to XML 4.1.2 DocBook format
Revision 0.629 Mar 2002Revised by: avi
Finished timezone mechanism on Linux. Created appendix. Now only drawings are needed.
Revision 0.424 Mar 2002Revised by: avi
All skeleton defined. All command examples written.
Revision 0.219 Mar 2002Revised by: avi
First DocBook version

Table of Contents
1. Why do We Need a Precise Clock?
1.1. On What Factors Does the Hardware-Clock Depend?
2. Computer Global Date and Time Concept
3. What are Time Zones?
3.1. Daylight Savings Time
3.2. Time Zones Examples
3.3. Time Zone Mechanism on Linux
4. The Correct Settings for Your Linux Box
4.1. Setting Time Zone
4.2. Setting the Hardware Clock
5. Accurate Global Time Synchronization
5.1. NTP: The Network Time Protocol
5.2. Building a Simple Time Synchronization Architecture
5.3. NTP Configurations
5.4. Watching Your Box Synchronizing
5.5. Configure to Automatically Run NTP at Boot
6. Precise Time with the chrony Program
6.1. How chrony Differs from the ntp Suite?
6.2. How to Use chrony?
A. About this Document