The latest Microsoft Windows operating systems have a time synchronisation utility installed by default called ‘Windows Time’. The Windows time service allows a Microsoft network to provide time synchronisation of machines in a domain. This article introduces how to configure the Microsoft Windows 2000 and 2003 operating systems to operate as a SNTPNTP time server. The article discusses how to change Windows registry entries to configure the Time Service.



Before modifying any Windows registry settings, it is a good idea to save the registry. In the even of any difficulties, the registry can be restored to its former state.

Windows 2000 Time Service

Windows 2000 has an integrated network time synchronization service, installed by default, which can be configured to synchronize to a Time Server. In fact, by changing associated registry settings, the service can act as both a time client and a time server to synchronize other network time clients.

The Windows Time service should be present in the systems service list. The application executable is 'w32time.exe'. The parameter list for time service should be present in the in the registry at:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParameters

The Windows 2000 operating system can operate as a time client and synchronise to a time server by setting the parameter 'NTP Server' to the IP address of a Time Server.

By default, the Windows 2000 machine will synchronize to the specified time server every 8 hours, or 3 times a day. This may not be enough to maintain accurate synchronization and can be easily increased. Setting the ‘Period’ parameter to how many times each day synchronisation is required can reduce the period. Setting the ‘Period’ parameter to 48 will activate synchronization with the time server once every half hour.

The Windows 2000 operating system can also be configured to act as a time server by setting the 'Local NTP' registry setting to '1'.

After changing any of the registry settings for the windows time service, the service must be restarted for the settings to take effect. The time service can be started or stopped from the service control applet in the Administrative Tools menu. The service can also be controlled via the DOS net command thus:

‘net start w32time’ and ‘net stop w32time’

Windows 2003 Time Service

With Windows 2003, Microsoft has expanded on the original Windows 2000 SNTP time service by providing a true NTP implementation. The Windows 2003 time service, installed by default, can synchronise to a NTP Server. Indeed, by changing registry settings, the time service can act as both a time server and client to synchronize other time clients in the domain.

The 'Windows Time' service should be present in the systems service list. The application executable is 'w32time.exe'. The parameter list for the Windows 2003 time service should be present in the registry at:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32Time

To configure the Windows 2003 operating system to synchronize to an external time server, edit the following registry entries:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParametersType

Set the ‘Type’ registry entry to ‘NTP’, which specifies synchronization to a NTP time server.

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeTimeProvidersNTPClientSpecialPollInterval

The ‘Special Poll Interval’ registry entry defines the period in seconds that the Windows 2003 operating system should poll the time server. A recommended value is 900, which equates to a polling period of every 15 minutes.

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeConfigAnnounceFlags

Set the ‘Announce Flags’ registry entry to 5 indicating a reliable time reference.



HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeTimeProvidersNTPServerEnabled

Changing the ‘Enabled’ flag to the value 1 enables the NTP Time Server.

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParametersNtpServer

The ‘NTP Server’ parameter is used to provide a list of DNS names or IP addresses, separated by a space, of time servers that the Windows 2003 operating system can synchronize to.

Troubleshooting the Time Service

A number of isuues may be encountered when configuring the Microsoft Windows Time Service. SNTP and NTP operates using the UDP protocol over TCP/IP. Therefore, the TCP/IP network protocol must be active for SNTPNTP to operate. Synchronisation issues may also arise when SNTPNTP attempts to synchronise to an inaccurate time server reference or if network delays are excessive.

Synchronising Network Device and Components

In addition to synchronizing Microsoft Windows servers and workstations, time servers can also be used to synchronise network devices, such as switches, routers and hubs. Any network infrastructure that can synchronise to a NTP or SNTP time server can be pointed to the Windows time server to obtain synchronisation. In this way the whole network and accompanying infrastructure can be accurately synchronised to a time reference.