Understanding Time Synchronization Concepts

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When you set your computer clock time manually, you apply an initial offset error that may exceed several seconds. In addition, a typical computer clock will lose or gain from several seconds to more than a minute per week if left free-running.

Microsoft Knowledge Base article 189706 states that:

• When you use the Date/Time tool in Control Panel to select a different year, the clock may stop until you click Apply or OK and the clock does not compensate for the length of time it was stopped.
• When you use the Date/Time tool to select a different month or date, the time may be decreased by 5-10 seconds.
• When you leave your computer on for an extended amount of time, the time may lose from two minutes to an hour per day.

This may or may not be acceptable, depending on the applications you run, your network environment, and your expectations.

Time synchronization is a process of bringing two clocks into phase so that their difference is zero. A typical time synchronization process may be divided into these steps:

1. Client software receives the correct time from a time server.
   
2. Then it compares the received time value to the time setting of the host computer.
3. If there is any difference, the computer clock is automatically adjusted to reflect the correct time.

The accuracy of time synchronization depends on the time protocol used and the limits of the underlying computer hardware and operating system.