How to Sync Time for Workgroup Machines with an External Time Source

Recently I worked on a case where they needed to Sync time for Workgroup machines with an external time source which is a domain member. They were trying to get the time synced with the command “W32Tm /resync”  and it gave an error and failed to complete.

Resolution

When the computers are part of a workgroup, you must manually configure the time synchronization settings. You might identify a computer as a locally reliable time source by configuring the Windows Time service on that computer. You can configure all other workgroup computers manually to synchronize their time with this local time source.
If the computers belong to an Active Directory domain, the Windows Time service configures itself automatically by using the Windows Time service that is available on domain controllers.
To synchronize the time on a member computer in an Active Directory domain, you can use w32tm /resync command.
To synchronize a workgroup server with a time source, you will have to follow the below commands.
        w32tm /config /syncfromflags:manual /manualpeerlist:peerlist
          w32tm /config /update
(Note:peerlist is the list of time servers)

Registry settings on the Time Server (Domain member)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config  > AnnounceFlags  = 10
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpServer  >> Enabled  =1

Registry settings on the clients (Workgroup members)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config  > AnnounceFlags  = 5
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpServer  >> Enabled  = 0
Commands to be run on the client to sync time:
          w32tm /config /syncfromflags:manual /manualpeerlist:peerlist
          w32tm /config /update
(Note:peerlist is the list of time servers)
Firewall settings: Port 123 is recommended to be open.
You may create a batchfile with these commands and run it as a batch file to automate the process.
More Information
Some references on Time Service Troubleshooting:
How to synchronize the time with the Windows Time service in Windows XP - http://support.microsoft.com/kb/307897
How to configure an authoritative time server in Windows Server - http://support.microsoft.com/kb/816042
Managing the Windows Time Service - http://technet.microsoft.com/en-us/library/cc737124.aspx
Restore Windows Time service on local computer to default settings - http://technet.microsoft.com/en-us/library/cc778779.aspx
Configuring a time source for the forest - http://technet.microsoft.com/en-us/library/cc784800.aspx
A List of the Simple Network Time Protocol Time Servers That Are Available on the Internet - http://support.microsoft.com/default.aspx?scid=kb;en-us;262680
Configuring Windows-based clients to synchronize time - http://technet.microsoft.com/en-us/library/cc785223.aspx