Maintaining Precise Time On Your Computer by Utilising NTP Servers

Maintaining Precise Time On Your Computer by Utilising NTP Servers
Computer servers and workstations have integrated real-time
clocks that are based on simple, cheap, crystal
oscillators. The real-time clock is battery backed and
maintains system time even when the computer is switched
off. However, crystal oscillators characteristics change
significantly with temperature variation, which can cause
the time to drift by several minutes each day. This article
describes how Internet or Intranet based NTP servers can be
utilised to maintain accurate time on a computer system.

NTP, or Network Time Protocol, was originally developed
over 25 years ago as a means of distributing accurate time
around the Internet. It is one of the oldest network
protocols still in use today. NTP allows network time
clients to synchronise to Internet based NTP time servers.
It is an integral part of the Internet network structure.

Many operating systems including Microsoft Windows, LINUX,
UNIX and Novell Netware integrate the ability to
synchronise their system time by utilising NTP or its
reduced sister protocol SNTP (Simple Network Time
Protocol). Most NTP clients only require a single, or
multiple, NTP server address to be specified and will
periodically synchronise with the specified NTP server.

There a large number of Internet hosted NTP servers. Most
synchronise with external timing reference such as GPS or
time and frequency radio broadcasts. NTP servers that
synchronise to an external timing reference are designated
as stratum 1 time servers, this is because they sit at the
head of the network time hierarchy. NTP servers that
synchronise to stratum1 time server are designated stratum
2 and so on.

Below is a list of a small number of the most popular NTP
servers available across the Internet. You should choose a
NTP server close to you geographic locality, so as to
reduce network round trip delays.

ntp.my-inbox.co.uk - Locality: United Kingdom.
time.nist.gov - Locality: United States. canon.inria.fr -
Locality: France. ptbtime1.ptb.de - Locality: Germany.
clock.isc.org - Locality: Canada.

Most NTP servers are based on the LINUX operating system.
The NTP software distribution is a freely downloadable
application supplied under the GNU public licence. NTP
source code and documentation can be obtained from the
'ntp.org' web-site. Under LINUX, NTP runs a daemon,
periodically contacting specified NTP servers and
synchronising system time.

Microsoft Windows operating systems utilise Microsoft's
proprietary time synchronisation service 'Windows Time'.
The Windows Time service can be configured via registry
settings to synchronise with network time servers at
specified intervals.

To conclude, Internet based NTP servers are readily
available free sources of precise time. Additionally, most
modern operating systems have the ability to contact and
synchronise with NTP servers without the need for
additional software. So, provided your network has an
Internet connection, there is no longer any need to
continue with inaccurate system time.

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David Evans is a technical author in the field of computer
networks and time synchronisation. David has built up a
wealth of experience in the field of time and frequency
solutions. For more information on NTP server systems,
please visit:
http://www.timetools.co.uk/ntp-servers/ntp-server-s5000.htm