You may notice that, after setting the correct time on your computer, later it may be off.  It may be off a small amount, or a large amount, if you do not reset it very often.   This is because the time is kept by an internal clock in your computer.  This clock is very often off slightly, due to variations in the internal hardware.

Everything in your computer, such as files, email, documents, and transactions, are time stamped.  The stamp is the time that your computer thinks it is.  If the internal time is off by very much, it can greatly affect a lot of different subsystems.

Windows, by default, will synchronize the time with any timeservers that it sees on your network.  If you have a Windows Server, it will announce itself as a time server.  Your Windows workstations will synchronize to it.  The problem is that the time on the server may or may not be correct.  Then end result is that the workstations and the server will have the same time, but that time may not be close to the actual time (Real time based on Greenwich Mean Time - GMT).

If you have a UNIX/Linux server, time synchronization is not turned on by default, in most of the versions.

The answer to this problem, is to synchronize the time, to a time server that is known to be correct.  Network Time Protocol, known as NTP, is straightforward to setup, in Windows and UNIX/Linux.  In this case your server, or one of your workstations, is setup to synchronize to an outside atomic clock.  The computer chosen, is configured to synchronize it's time on a regular basis, usually every 10 minutes.  This computer is then configured to act as a time server for the rest of your network.

To recap, you can have one, computer that synchronizes frequently to one of the public atomic clocks. The Atomic Clock is keeping it's time very close to the actual time.  Usually within a few milliseconds.  The rest or your computers then synchronize to this computer.  The result is that all of your computers keep the correct time, within a very small margin of error.

You can setup more than one local time server, to synchronizes to a public atomic clock.  The rest of your computers can then be configured to synchronize with all of your local time servers.  This adds reliability, in that if one time server is down, the other is usually still available.  It also adds accuracy, as your other computers will average the time that each time server reports.

Windows workstations normally request the time from a Microsoft time server time.microsoft.com.  To use the ideas above, you can easily override this from the Clock ICON in the System Tray.

Let us know, if you would like some help tuning your time settings for improved accuracy.