Pakthailand.com

This article attempts to explain NTP (Network Time Protocol) and how it is utilised in time servers to synchronise computer networks.

A Guide to NTP and Computer Network Time Synchronisation

Network Time Protocol (NTP) is one of the Internet’s
oldest protocols. In use for over 25 years, NTP is still under development
with version 4 currently in progress. Put simply, NTP is a computer
protocol that is used to
synchronise the clocks of computer systems; usually to an
authoritative time reference such as UTC (Coordinated Universal Time or Temps Universel Coordonné)
which became the international standard of time after the development of
atomic clocks.

Without
NTP, time would not be consistent over any two computers, let alone a network
of hundreds or thousands of machines Seconds would be lost here and gained
there, causing major confusion, as time, in the form of timestamps,
is intrinsically
important to the function of routers and networks. It provides the only frame
of reference between all devices on a network NTP is now
everywhere and is an integral part of modern computer networking, as inventor
and developer, Dr David Mills from the University of Delaware explains:

“Just about everything today that can be connected to a
network wire has support for NTP - print servers, wi-fi access points,
routers of every stripe and even battery backup systems. NTP subnets are in
space, on the seabed, onboard warships and on every continent, including
Antarctica. NTP comes with Windows/XP and NT2000, as well as all flavours of
Unix. About 25 million clients implode on the NTP time servers at NIST
alone.?

The
way NTP works is relatively straight forward. NTP timestamps relay the
seconds from a set point in time (known as the prime epoch, set at 00:00 1
January 1900) The NTP algorithm
(Marzullo’s algorithm)
then uses this timestamp to determine the amount to advance or retreat
the system or network clock. NTP is accurate to within 10
milliseconds over the public Internet (1/100th of a second) and can
perform even better over LANs with accuracies of 200 microseconds (1/5000th
of a second) under ideal conditions.

The NTP program (known as a daemon on UNIX and a service on
Windows) runs in the background and refuses to believe the time it is told
until several exchanges have taken place, each passing a set of tests. Only if
the replies from a server satisfy these tests or ?protocol specifications’, the
server is considered. It usually takes about five minutes (five good samples)
until a NTP server is accepted as a
synchronization source.

All , is used in some devices and
applications where high accuracy timing is not as important and is also
included as standard in Windows software (although more recent versions of
Microsoft Windows have the full NTP installed and the source code is free and
readily available on the Internet).

NTP can
synchronise time over the Internet but it should be noted that Microsoft
and others recommend that external time references are used rather than
Internet based ones as these can’t be authenticated.

Specialist time servers are available that synchronise networks to UTC time either
over the GPS network or specialist radio transmission. These NTP servers and GPS
time servers can
provide timing information to within a few nanoseconds of UTC as long as there
is an antenna situated with a good view of the sky.

About the author

Tags: atomic clocks, battery backup systems, computer network time, computer networking, computer protocol, coordinated universal time, frame of reference, modern computer, network clock, network time protocol, nt2000, ntp time servers, print servers, seabed, subnets, time reference, time synchronisation, timestamps, university of delaware, warships

Share This

Related Posts

• Home Based Business Network System ? Lesson 1
• Windows Security Tips
• Best Spyware Removers - What You Need To Know To Keep Your Computer Safe
• Resources that Can Help You Be Successful In Network Marketing
• Computer Fires: How Vulnerable is Your PC?