windows time sync

1. On the domain controller of the root forest , you may follow the steps to configure the Windows Time service to sync time with the authoritative time source.

a. Open a Command Prompt.

b. Type the following command to display the time difference between the local computer and a target computer, and then press ENTER: (without quotation mark)

"w32tm /stripchart /computer: time.windows.com /samples:5 /dataonly”

Please note:

The Microsoft time server (time.windows.com) uses NIST, the National Institute of Standards and Technology, located in Boulder, Colorado, as its external time provider. NIST provides the Automated Computer Time Service (ACTS), which can set a computer clock with an uncertainty of less than 10 milliseconds. The U.S. Naval Observatory (USNO) Time Service Department in Washington, D.C., is another source for accurate time synchronization in the United States. Many other sites exist throughout the world that you can use for time synchronization.

c. Open UDP port 123 for outgoing traffic if needed.

d. Open UDP port 123 (or a different port you have selected) for incoming NTP traffic.

e. Type the following command to configure the PDC emulator and then press ENTER: (without quotation mark)

"w32tm /config /manualpeerlist: time.windows.com /syncfromflags:manual /reliable:yes /update"

2. The computers that are joined to a domain are configured to synchronize from a manual time source. Please use the following procedure to configure a client computer that is currently synchronizing with a manually specified computer, to automatically synchronize time with the domain hierarchy.

You may follow the steps to configure a client computer for automatic domain time synchronization

a. Open a Command Prompt.

b. Type the following command and then press ENTER:

w32tm /config /syncfromflags: domhier /update

c. Type the following command and then press ENTER:

net stop w32time

d. Type the following command and then press ENTER:

net start w32time

You may also use Group Policy to make all the domain clients to sync time with PDC emulator in the domain.

You may find the Group Policy settings used to configure W32Time in the Group Policy Object Editor snap-in in the following locations:
Configure Global Configuration Settings here
Computer Configuration\Policies\Administrative Templates\System\Windows Time Service

Configure Windows NTP Client settings here
Computer Configuration\Administrative Templates\System\Windows Time Service\Time Providers

More reference:

How to configure an authoritative time server in Windows Server 2003
http://support.microsoft.com/kb/816042/en-us

Windows Time Service Best practices
http://technet2.microsoft.com/windowsserver/en/library/517e74d7-40e9-41bd-93aa-48b610b936321033.mspx?mfr=true

Reference:
http://social.technet.microsoft.com/Forums/en-US/winservergen/thread/96278628-03a1-4b3d-90d9-2208a65a1210/