Configure a Manual Time Source for a Selected Client Computer

Applies To: Windows Server 2008, Windows Server 2008 R2

You can use this procedure to configure a manual time source for a selected client computer. The default method of synchronizing time in a Windows forest is through the domain hierarchy, in which a client connects to a domain controller in its domain as its time source. A manual time source is a specified computer or computers from which the client synchronizes its time when it cannot synchronize through the domain hierarchy. To configure a computer for automatic domain time synchronization, see Configure a Client Computer for Automatic Domain Time Synchronization.

Before you configure a manual time source for a client computer, you can determine the time difference between the time source and the computer as a means of testing basic Network Time Protocol (NTP) communication. After you complete the configuration of the manual time source on the client computer, be sure to monitor the System log in Event Viewer for Windows Time service (W32time) errors.

Note

The following procedure uses the w32tm command-line tool. For more information about the w32tm command, type w32tm /? at a command prompt or see Windows Time Service Tools and Settings (https://go.microsoft.com/fwlink/?LinkId=112116).

Membership in the local Administrators group, or equivalent, is the minimum required to complete this procedure locally. Membership in the Domain Admins group, or equivalent, is the minimum required to complete this procedure remotely. Review details about using the appropriate accounts and group memberships at Local and Domain Default Groups (https://go.microsoft.com/fwlink/?LinkId=83477).

To configure a manual time source for a selected client computer

1. Open a Command Prompt as an administrator: On the Start menu, right-click Command Prompt, and then click Run as administrator. If the User Account Control dialog box appears, confirm that the action it displays is what you want, and then click Continue.

2. To display the time difference between the local computer and a time source, at the command prompt, type the following command, and then press ENTER:

   w32tm /stripchart /computer:<target> /samples:<n> /dataonly
   

   Parameter	Description
   W32tm /stripchart	Displays a strip chart of the offset between synchronizing computers. A strip chart plots two-dimensional data—in this case, the local time and the offset.
   /computer:<target>	Specifies the Domain Name System (DNS) name or IP address of the NTP server that you are comparing the local computer's time against, such as time.windows.com.
   /samples:<n>	Specifies the number of time samples that will be returned from the target computer to test basic NTP communication.
   /dataonly	Specifies that results show only data, not graphics.

3. Open UDP port 123 for outgoing traffic on the firewall, if necessary.

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

5. To configure a manual time source for the selected computer, at the command prompt, type the following command, and then press ENTER:

   w32tm /config /manualpeerlist:<peers> /syncfromflags:manual /update
   

   Parameter	Description
   W32tm /config /update	Configures the computer for time synchronization.
   /manualpeerlist:<peers>	Specifies the list of Domain Name System (DNS) names or IP addresses for the NTP time source with which the primary domain controller (PDC) emulator synchronizes. (This list is referred to as the manual peer list.) For example, you can specify time.windows.com as the NTP time server. When you specify multiple peers, use a space as the delimiter and enclose the names of the peers in quotation marks.
   /syncfromflags:manual	Specifies that time is synchronized with peers in the manual peer list.

Tip

For links to SNTP server lists, see article 262680 in the Microsoft Knowledge Base (https://support.microsoft.com/kb/262680).