How To Configure a Windows Based Network Time Server

In modern computer networks, computer time synchronization is of critical importance. Many transaction-processing operations require accurate synchronisation of client and server in order to maintain a coherent processing order.

The latest versions of the Microsoft Windows operating systems have a time synchronization utility built into the operating system, called ‘w32time’. The Microsoft time applet runs as a service and allows a Windows network to provide synchronization of a domain.

This article discusses how to configure the latest Windows operating systems to operate as a network time server. The article describes how to change the registry entries to configure w32time.

Before changing any of the registry settings, it is generally a good idea to backup the registry. This is so that if any problems arise, the registry can be restored to its previous state.

Microsoft Windows 2000 Based Network Time Server

Microsoft Windows 2000 has a pre-installed network time synchronization service, which can synchronize to a NTP Time Server. By changing the time service registry settings, the service can also act as a network time client and time server to synchronize other computers in the domain.

Firstly check to ensure the 'Windows Time' service, w32time, is present in the systems service list. The application executable is 'w32time.exe'. The parameter list for w32time should be present in the in the registry at: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters

The Windows 2000 operating system can operate as a time client and synchronise to a time server by setting the parameter 'NTP time 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. In order to maintain more accurate synchronization, the synchronization period can easily be reduced. Set the ‘Period’ parameter to how many times each day synchronisation is required. Setting the parameter to 48 will activate synchronization with the time server once every half hour, which is about right.

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

After changing the registry settings for w32time, the service must be restarted for the settings to be activated. 'W32time' can be re-started from the service control panel in the Administrative Tools menu. The service can also be controlled via the DOS net command by using: ‘net start w32time’ and ‘net stop w32time’

Microsoft Windows 2003 Based Network Time Server

Microsoft Windows 2003 expanded on the original Windows 2000 SNTP synchronization service by providing a true NTP implementation. The pre-installed Windows 2003 time service can synchronize to a NTP Server. By modifying registry settings, the time service can act as both a time server and client to synchronize other servers and workstations in the domain.

Ensure that the 'Windows Time' service, w32time, is present in the systems service list. The registry parameters for the Windows 2003 w32time should be present in the registry at: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config\AnnounceFlags
Set the ‘Announce Flags’ registry entry to 5 indicating a reliable time reference.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NTPServer\Enabled
Changing the ‘Enabled’ flag to the value 1 enables the NTP Time Server.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters\Type
Set the ‘Type’ registry entry to ‘NTP’, which specifies synchronization to a NTP time server.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NTPClient\SpecialPollInterval
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_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters\NtpServer
This parameter is used to provide domain names or IP addresses of NTP time servers that the operating system can synchronize to. Each domain name or IP address should be separated by a space.

Debugging the Windows Time Synchronisation Service

A number of problems may be encountered when configuring the Windows time synchronisation service. Both the SNTP and NTP protocols operate using the UDP protocol. Therefore, the TCP/IP network protocol must be active for SNTP\NTP to operate correctly. Additionally, synchronisation problems may become apparent when SNTP or NTP attempts to synchronise to an inaccurate time reference or if network round-trip delays are excessive.

Synchronizing Time on Other Network Devices

In addition to synchronizing Microsoft Windows machines, network time servers can also be utilised to synchronise other network devices, such as switches, routers and hubs. Any network device that can synchronise to a NTP or SNTP time server can be pointed to the Windows network time server to synchronise time. In this way the whole network and accompanying devices can be synchronised to an accurate time reference.

Biography:
David Evans is an experienced Systems Engineer who has been involved in the development of NTP time server systems over a number of years. Ranging from dedicated GPS NTP server systems to NTP synchronised Ethernet digital wall clock systems, Dave has a wealth of experience in the field of network time synchronisation. Please click here for more information about NTP server and time server solutions.