Synchronizing your computer clock
If your computer is a member of a domain, your computer clock is probably synchronized automatically by a network time server If your computer is not a member of a domain, you can synchronize your computer clock with an Internet time server.
If synchronization is enabled, your computer clock is synchronized with an Internet time server once a week. However, if you don't have a continuous Internet connection through a cable modem or DSL modem, the automatic synchronization might not always occur. In that case, you can force an immediate synchronization by clicking the Update Now button on the Internet Time tab in Date and Time in Control Panel. This tab is only available if your computer is not a member of a domain.
If time synchronization fails
When you click the Update Now button, your clock should be synchronized immediately. If it fails, it may be for one of the following reasons:
You are not connected to the Internet. Establish an Internet connection before you attempt to synchronize your clock.
Your personal or network firewall prevents clock synchronization. Most corporate and organizational firewalls will block time synchronization, as do some personal firewalls. Home users should read your firewall documentation for information about unblocking network time protocol (NTP). You should be able to synchronize your clock if you switch to the Microsoft Internet Connection Firewall.
The Internet time server is too busy or not available for some reason. If this is the case, try synchronizing your clock later, or update it manually by double-clicking the clock on the taskbar You can also try using a different time server.
The date set on your computer is inaccurate. Internet time servers will not synchronize your clock if the date is incorrect. Ensure that the date is set correctly in Date and Time Properties in Control Panel.
To open Date and Time, click Start, click Control Panel, click Date, Time, Language, and Regional Options, and then click Date and Time.
An Internet time server updates the date set by your computer as well as the time.
The Update Now button is not available unless the Automatically synchronize with an Internet time server check box is selected.
You can change the time on your computer clock manually on the Date & Time tab in Date and Time in Control Panel. You can also open Date and Time by double-clicking the clock on the taskbar.
Update the time on your computer
Change your computer's time and time zone
Change the clock synchronization server
Turn off clock synchronization
Internet Connection Firewall overview