Time Synchronisation

Many people are probably familiar with the Internet Time tab when setting their clock in Windows. This is a basic form of NTP (Network Time Protocol) called SNTP (Simple Network Time Protocol) that polls a NTP server every so often to synchronize time to. However, full NTP does a lot more, such as polling several servers to determine what is the best and most stable times source.

Creating your own NTP time server is relatively straightforward and if you are a resident of the US then the simplest way is to use a relatively cheap receiver module, set to receive the WWVB timing signal which is broadcast by NIST (National Institute of Standards and Time) at a frequency of 60 kHz.

To create your own product using the WWVB time signal, WWVB receiver modules, are readily available at low cost. When looking for a receiver module there are several points to consider:

There should be a simple interface to allow easy integration of accurate timekeeping into electronic equipment etc. The receiver should use dedicated chips designed specifically to receive the WWVB (USA) time signal. The advantage of these over other solutions is that the modules include the necessary support electronics, tuned crystals, etc and are preassembled, tested and are usually in miniature form.

When combined with a suitable Antenna the receiver module acts as a complete time code receiver, providing a serial digital data output stream for external decoding.

Once assembled and tested so the module is receiving a signal it can then be connected to your computer or server.

Once connected the time server should be configured using the registry editor. Simply follow these steps:

Locate the following subkey: HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParametersType
In the right pane, right-click Type then click Modify, in edit Value type NTP in the Value data box then click OK.

Locate the following subkey: HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeConfigAnnounceFlags.

In the right pane, right-click AnnounceFlags and click Modify. The ‘AnnounceFlags’ registry entry indicates whether the server is a trusted time reference, 5 indicates a trusted source so in the Edit DWORD Value box, under Value Data, type 5, then click OK.

To enable the Network Time Protocol; NTPserver, locate and click: HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeTimeProvidersNtpServer

In the right pane, right-click Enabled, then click Modify. In the Edit DWord Value box, type 1 under Value data, then click OK.

Now go back and click on: HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParametersNtpServer

In the right pane, right-click NtpServer, then Modify, in the Edit DWORD Value under Value Data type In the right pane, right-click NtpServer, then Modify, in the Edit DWORD Value under Value Data type the Domain Name System (DNS), each DNS must be unique and you must append 0×1 to the end of each DNS name otherwise changes will not take effect.

Now click Ok then locate and click the following: HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeTimeProvidersNtpClientSpecialPollInterval

In the right pane, right-click SpecialPollInterval, then click Modify. In the Edit DWORD Value box, under Value Data, type the number of seconds you want for each poll, ie 900 will poll every 15 minutes, then click OK.

To configure the time correction settings, locate: HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32Timeconfig

In the right pane, right-click MaxPosPhaseCorrection, then Modify, in the Edit DWORD Value box, under Base, click Decimal, under Value Data, type a time in seconds such as 3600 (an hour) then click OK.

Now go back and click: HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32Timeconfig In the right pane, right-click MaxNegPhaseCorrection, then Modify.

In the Edit DWORD box under base, click Decimal, under value data type the time in seconds you want to poll such as 3600 (polls in one hour) Exit Registry Editor

Now, to restart windows time service, click Start, Run (or alternatively use the command prompt facility) and type:

net stop w32time && net start w32time. And that’s it your time server should be now up and running.

This article explains how to configure Windows 2003 to run as a Network Time Server.

Time synchronisation in modern computer networks is essential, all computers need to know the time as many applications, from sending an email to storing information are reliant on the PC knowing when the event took place.

Microsoft Windows Server from 2000 onwards has a time synchronisation utility built into the operating system called Windows Time (w32time.exe) which can be configured to operate as a network time server.

Windows 2003 Server can easily set the system clock to use UTC (Coordinated Universal Time, the World’s time standard) by accessing an Internet source (either: time.windows.com or time.nist.gov). To achieve this, a user merely has to double click the clock on their desktop and adjust the settings in the Internet Time tab.

It must be noted however, that Microsoft and other operating system manufacturers strongly advise that external timing references should be used as Internet sources can’t be authenticated.

To configure the Windows Time service to use an external time source, click Start, Run and type regedit then click OK.
Locate the following subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters\Type

In the right pane, right-click Type then click Modify, in edit Value type NTP in the Value data box then click OK.

Locate the following subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config\AnnounceFlags.

In the right pane, right-click AnnounceFlags and click Modify. The ‘AnnounceFlags’ registry entry indicates whether the server is a trusted time reference, 5 indicates a trusted source so in the Edit DWORD Value box, under Value Data, type 5, then click OK.

Network Time Protocol (NTP) is an Internet protocol used for the transfer of accurate time, providing time information along so that a precise time can be obtained.

To enable the Network Time Protocol; NTPserver, locate and click:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpServer\

In the right pane, right-click Enabled, then click Modify.

In the Edit DWord Value box, type 1 under Value data, then click OK.

Now go back and click on

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters\NtpServer

In the right pane, right-click NtpServer, then Modify, in the Edit DWORD Value under Value Data type In the right pane, right-click NtpServer, then Modify, in the Edit DWORD Value under Value Data type the Domain Name System (DNS), each DNS must be unique and you must append 0×1 to the end of each DNS name otherwise changes will not take effect.

Now click Ok.

Locate and click the following

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient\SpecialPollInterval

In the right pane, right-click SpecialPollInterval, then click Modify.

In the Edit DWORD Value box, under Value Data, type the number of seconds you want for each poll, ie 900 will poll every 15 minutes, then click OK.

To configure the time correction settings, locate:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\config

In the right pane, right-click MaxPosPhaseCorrection, then Modify, in the Edit DWORD Value box, under Base, click Decimal, under Value Data, type a time in seconds such as 3600 (an hour) then click OK.

Now go back and click:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\config

In the right pane, right-click MaxNegPhaseCorrection, then Modify.

In the Edit DWORD box under base, click Decimal, under value data type the time in seconds you want to poll such as 3600 (polls in one hour)

Exit Registry Editor

Now, to restart windows time service, click Start, Run (or alternatively use the command prompt facility) and type:

net stop w32time && net start w32time

And that’s it your time server should be now up and running.

All versions of Windows Server since 2000 have included a time synchronization facility, called Windows Time Service (w32time.exe), built into the operating system. This can be configured to operate as a network time server synchronizing all machines to a specific time source.

Windows Time Service uses a version of NTP (Network Time Protocol), normally a simplified version, of the Internet protocol which is designed to synchronise machines on a network, NTP is also the standard for which most computer networks across the global use to synchronise with.

Choosing the correct time source is vitally important. Most networks are synchronized to UTC (Coordinated Universal Time) source. UTC is a global standardized time based on atomic clocks which are the most accurate time sources.

UTC can be obtained over the Internet from such places as time.nist.gov (us Naval Observatory) or time.windows.com (Microsoft) but it must be noted that internet time sources can not be authenticated which can leave a system open to abuse and Microsoft and others advise using an external hardware source as a reference clock such as a specialized network time server.

Network time servers receive their time source from either a specialist radio transmission from national physics laboratories which broadcast UTC time taken from an atomic clock source or by the GPS network which also relays UTC as a consequence of needing it to pin point locations.

NTP can maintain time over the public Internet to within 1/100th of a second (10 milliseconds) and can perform even better over LANs.

To configure Windows Time Service to use an external time source simply follow these instructions.

Locate the registry subkey.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters
Right click type then Modify the Value by inserting NTP in the Value Data box.
Right click ReliableTimeSource, then Modify the Edit DWORD Value box, by inserting 0 (zero).
Right-click NtpServer then Modify the Edit Value by typing the Domain Name System (DNS), (note each DNS must be unique).

Now locate the original subkey and right-click Period Modify the Edit DWORD Value box with the poll interval (how often a NTP server polls the time), under Value Data (recommended 24)

Run the following command line, Net stop w32time && net start w32time.
Now enable NTP by locating the subkey,
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpServer\
Right click Enabled and modify the Value data box by typing 1.

Right Click SpecialPollInterval in the right pain of the subkey
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient\SpecialPollInterval.
Edit the DWORD value box the time you want for each poll (900 will poll every 15 minutes)

Locate HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\config

To configure the time correction settings right click MaxPosPhaseCorrection, then modify the DWORD Value box with a time in seconds such (select decimal under base first, 3600 = one hour)

Now do the same for MaxNegPhaseCorrection the restart windows time service by running (or alternatively use the command prompt facility) net stop w32time && net start w32time.

To synchronise each machine simply type W32tm/ -s in the command prompt and the time server should now be working correctly (note it may take several polls before the correct time is displayed).

Microsoft Windows XP has a time synchronisation utility built into the operating system called Windows Time (w32time.exe) which can be configured to operate as a network time server. It can be configured to both synchronise a network using the internal clock or an external time source.

NTP (Network Time Protocol) is a protocol already installed on Windows XP and Windows Time uses it to keep machines synchronised to the single time source. There are several timing sources available on the Internet but Microsoft and others strongly recommend that you configure a time server with a hardware source rather than from the Internet where there is no authentication.

Specialist NTP time servers are available that can receive a reliable time source via the GPS signal or specialist radio transmissions that get their time from atomic clocks.

If you wish to configure Windows XP to operate as a time server then first thing is to locate the Windows Time subkey. To do this:

Run Regedit (Click start/run/then type REGEDIT/and click enter.

Note: editing your system registry can cause problems with your system. It is advisable to back up your system before editing the registry.

Now locate the following subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\parameters\

Right click the right-hand side and click Modify. In the Edit Value box, under Value Data, type NTP and then click OK.

Now go to the Config folder and right-click AnnounceFlags, Modify and in the Edit DWORD Value box, under Value Data, type 5, and then click OK.

Locate this subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient\

Right-click in the right-side window and Modify. Edit the DWORD value box and type the number of seconds you want for each poll under Value data, i.e.: 900 will equal 15 minutes. The poll field represents the polling interval between NTP poll packets.

To enable the NTP server locate the subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpServer\

Right click enabled (in the right-hand window) then Modify. Edit the DWORD Value and type 1. Right-click NtpServer, then Modify and in the Edit DWORD Value under Value Data type Peers, then click OK.

Locate: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\config

In the right pane, right-click MaxPosPhaseCorrection, then Modify, in the Edit DWORD Value box, under Base, click Decimal, under Value Data, type a time in seconds such as 3600 (an hour) then click OK. This adjusts the connection settings.

Now go back and click:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\config

In the right pane, right-click MaxNegPhaseCorrection, then Modify.

In the Edit DWORD box under base, click Decimal, under value data type the time in seconds you want to poll such as 3600 (an hour).

Exit Registry then restart windows time service by clicking Start/Run then typing:
net stop w32time && net start w32time.
on each computer, other than the domain controller, type: W32tm/resync/rediscover.
The time server should be now up and running.

Network Time Protocol (NTP) is one of the Internet’s oldest protocols still in use. Developed by Dr David Mills from the University of Delaware, it has been in constant use and continually updated since 1985. NTP is a protocol designed to synchronize the clocks on computers and networks across the Internet or Local or Wider Area Networks (LANs/WANS).

In a modern global economy time synchronisation is essential for carrying out time sensitive transactions such as booking an airline ticket to bidding on an Internet auction site. If clocks were not synchronised to the same time you may find your airline seat sold after you had bought it and Ebay’s administrators would not be able to discover whose bid was the latest.

NTP is a multi-tiered system, each tier being called a stratum. Servers at each tier communicate with each other (peer) and provide time to lower strata. Servers at the top stratum, stratum 1 connect to an atomic clock either over the Internet or by a radio or GPS receiver while a stratum 2 server will connect to a stratum 1.

NTP uses an algorithm (Marzullo’s algorithm) to synchronise time on a network using time scales like UTC (Coordinated Universal Time or Temps Universel Coordonné) and can support such features as leap seconds – added to compensate for the slowing of the Earth’s rotation.

NTP (version 4 being the latest) can maintain time over the public Internet to within 10 milliseconds (1/100th of a second) and can perform even better over LANs with accuracies of 200 microseconds (1/5000th of a second) under ideal conditions.

NTP time servers work within the TCP/IP suite and rely on UDP (User Datagram Protocol). A less complex form of NTP called Simple Network Time Protocol (SNTP) that does not require the storing of information about previous communications, needed by NTP, is used in some devices and applications where high accuracy timing is not as important and is also included as standard in Windows software (although more recent versions of Microsoft Windows have the full NTP installed and the source code is free and readily available on the Internet).

The NTP program (known as a daemon on UNIX and a service on Windows) runs in the background and refuses to believe the time it is told until several exchanges have taken place, each passing a set of tests. If the replies from a server satisfy these ‘protocol specifications’, the server is accepted. It usually takes about five good samples (five minutes) until a NTP server is accepted as a source for synchronisation.

Synchronisation with NTP is relatively simple, it synchronises time with reference to a reliable clock source such as an atomic clock, although these are extremely expensive and are generally only to be found in large-scale physics laboratories, however NTP can use either the Global Positioning system (GPS) network or specialist radio transmission to receive UTC time from these clocks.

A simplified version of NTP called Simple Network Time Protocol (SNTP) exists that does not require the storing of information about previous communications as required by NTP. It is used in some devices and applications where high accuracy timing is not as important and is installed on older versions of Microsoft Windows. Windows since 2000 has included the Windows Time Service (w32time.exe) which uses SNTP to synchronise the computer clock. NTP is also available on UNIX and LINUX (download via NTP.org).

Time synchronisation in modern computer networks is essential, all computers need to know the time as many applications, from sending an email to storing information are reliant on the PC knowing when the event took place.

Microsoft Windows Server from 2000 onwards has a time synchronisation utility built into the operating system called Windows Time (w32time.exe) which can be configured to operate as a network time server.

Windows Server 2008 can easily set the system clock to use UTC (Coordinated Universal Time, the World’s time standard) by accessing an Internet source (either: time.windows.com or time.nist.gov).

To achieve this, a user merely has to double click the clock on their desktop and adjust the settings in the Internet Time tab.

It must be noted however, that Microsoft and other operating system manufacturers strongly advise that external timing references should be used as Internet sources can’t be authenticated.

To configure the Windows Time service to use an external time source, click Start, Run and type regedit then click OK.

Locate the following subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters\Type
In the right pane, right-click Type then click Modify, in edit Value type NTP in the Value data box then click OK.

Locate the following subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config\AnnounceFlags.
In the right pane, right-click AnnounceFlags and click Modify. The ‘AnnounceFlags’ registry entry indicates whether the server is a trusted time reference, 5 indicates a trusted source so in the Edit DWORD Value box, under Value Data, type 5, then click OK.

Network Time Protocol (NTP) is an Internet protocol used for the transfer of accurate time, providing time information along so that a precise time can be obtained
To enable the Network Time Protocol; NTPserver, locate and click:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpServer\
In the right pane, right-click Enabled, then click Modify.

In the Edit DWord Value box, type 1 under Value data, then click OK.

Now go back and click on
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters\NtpServer
In the right pane, right-click NtpServer, then Modify, in the Edit DWORD Value under Value Data type the Domain Name System (DNS), each DNS must be unique and you must append 0×1 to the end of each DNS name otherwise changes will not take effect.

Now click Ok.

Locate and click the following
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient\SpecialPollInterval
In the right pane, right-click SpecialPollInterval, then click Modify.

In the Edit DWORD Value box, under Value Data, type the number of seconds you want for each poll, ie 900 will poll every 15 minutes, then click OK.
To configure the time correction settings, locate:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\config
In the right pane, right-click MaxPosPhaseCorrection, then Modify, in the Edit DWORD Value box, under Base, click Decimal, under Value Data, type a time in seconds such as 3600 (an hour) then click OK.
Now go back and click:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\config
In the right pane, right-click MaxNegPhaseCorrection, then Modify.

In the Edit DWORD box under base, click Decimal, under value data type the time in seconds you want to poll such as 3600 (polls in one hour)
Exit Registry Editor
Now, to restart windows time service, click Start, Run (or alternatively use the command prompt facility) and type:

net stop w32time && net start w32time
And that’s it your time server should be now up and running.

Nearly all a computers activity involves time whether logging a timestamp for when a network was accessed to sending an email, knowing the time is crucial for computer applications.

All computers have an on-board clock that provides time and date information. These Real Time Clock (RTC) chips are battery backed so that even when off they can maintain time, however these RTC chips are mass produced and cannot maintain accurate time and tend to drift.

For many applications this can be quite adequate, however if a computer is on a network and needs to talk to other machines, failing to be synchonised to the correct time can mean many time-sensitive transactions can not be completed and can even leave the network open to security threats.

All versions of Windows Server since 2000 have included a time synchronization facility, called Windows Time Service (w32time.exe), built into the operating system. This can be configured to operate as a network time server synchronizing all machines to a specific time source.

Windows Time Service uses a version of NTP (Network Time Protocol), normally a simplified version, of the Internet protocol which is designed to synchronise machines on a network, NTP is also the standard for which most computer networks across the global use to synchronise with.

Choosing the correct time source is vitally important. Most networks are synchronized to UTC (Coordinated Universal Time) source. UTC is a global standardized time based on atomic clocks which are the most accurate time sources.

UTC can be obtained over the Internet from such places as time.nist.gov (us Naval Observatory) or time.windows.com (Microsoft) but it must be noted that internet time sources can not be authenticated which can leave a system open to abuse and Microsoft and others advise using an external hardware source as a reference clock such as a specialized NTP server.

NTP servers receive their time source from either a specialist radio transmission from national physics laboratories which broadcast UTC time taken from an atomic clock source or by the GPS network which also relays UTC as a consequence of needing it to pin point locations.

NTP can maintain time over the public Internet to within 1/100th of a second (10 milliseconds) and can perform even better over LANs.

Network Time Protocol (NTP) is one of the Internet’s oldest protocols still in use. Developed by Dr David Mills from the University of Delaware, it has been in constant use and continually updated since 1985. NTP is a protocol designed to synchronize the clocks on computers and networks across the Internet or Local or Wider Area Networks (LANs/WANS).

In a modern global economy time synchronisation is essential for carrying out time sensitive transactions such as booking an airline ticket to bidding on an Internet auction site. If clocks were not synchronised to the same time you may find your airline seat sold after you had bought it and Ebay’s administrators would not be able to discover whose bid was the latest.

NTP is a multi-tiered system, each tier being called a stratum. Servers at each tier communicate with each other (peer) and provide time to lower strata. Servers at the top stratum, stratum 1 connect to an atomic clock either over the Internet or by a radio or GPS receiver while a stratum 2 server will connect to a stratum 1.

NTP uses an algorithm (Marzullo’s algorithm) to synchronise time on a network using time scales like UTC (Coordinated Universal Time or Temps Universel Coordonné) and can support such features as leap seconds – added to compensate for the slowing of the Earth’s rotation.

NTP (version 4 being the latest) can maintain time over the public Internet to within 10 milliseconds (1/100th of a second) and can perform even better over LANs with accuracies of 200 microseconds (1/5000th of a second) under ideal conditions.

NTP time servers work within the TCP/IP suite and rely on UDP (User Datagram Protocol). A less complex form of NTP called Simple Network Time Protocol (SNTP) that does not require the storing of information about previous communications, needed by NTP, is used in some devices and applications where high accuracy timing is not as important and is also included as standard in Windows software (although more recent versions of Microsoft Windows have the full NTP installed and the source code is free and readily available on the Internet).

The NTP program (known as a daemon on UNIX and a service on Windows) runs in the background and refuses to believe the time it is told until several exchanges have taken place, each passing a set of tests. If the replies from a server satisfy these ‘protocol specifications’, the server is accepted. It usually takes about five good samples (five minutes) until a NTP server is accepted as a source for synchronisation.

Synchronisation with NTP is relatively simple, it synchronises time with reference to a reliable clock source such as an atomic clock, although these are extremely expensive and are generally only to be found in large-scale physics laboratories, however NTP can use either the Global Positioning system (GPS) network or specialist radio transmission to receive UTC time from these clocks.

A simplified version of NTP called Simple Network Time Protocol (SNTP) exists that does not require the storing of information about previous communications as required by NTP. It is used in some devices and applications where high accuracy timing is not as important and is installed on older versions of Microsoft Windows. Windows since 2000 has included the Windows Time Service (w32time.exe) which uses SNTP to synchronise the computer clock. NTP is also available on UNIX and LINUX (download via NTP.org).

Computer time synchronisation is highly important in modern computer networks, precision and time synchronization is critical in many applications, particularly time sensitive transactions. Just imagine buying an airline seat only to be told at the airport that the ticket was sold twice because it was purchased afterwards on a computer that had a slower clock!

Modern computers do have internal clocks called Real Time Clock chips (RTC) that provide time and date information. These chips are battery backed so that even during power outages, they can maintain time but personal computers are not designed to be perfect clocks. Their design has been optimized for mass production and low-cost rather than maintaining accurate time.

For many applications, this is can be quite adequate, although, quite often machines need time to be synchronised with other PC’s on a network and when computers are out of sync with each other problems can arise such as sharing network files or in some environments even fraud!

Microsoft Windows 2000 has a time synchronisation utility built into the operating system called Windows Time (w32time.exe) which can be configured to operate as a network time server. Microsoft and others strongly recommend that you configure a time server with a hardware source rather than from the internet where there is no authentication.

If you want to configure Windows Time service to use the internal hardware clock, then first check that w32time is located in the system services list in the registry, to check:

Click Start, Run then type regedit then click ok.
Locate and then click the following registry entry:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time

It is highly recommended that you back up the registry as serious problems may occur if you modify the registry incorrectly, modifications to the registry are done at your own risk.

To begin configuration for an internal clock, click on the following subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters
In the right pane, right-click ReliableTimeSource, then click modify.
In Edit DWORD Value, type 1 in the Value Data box, then click OK
Exit Registry Editor

To restart the Windows Time Service click Start, Run (or alternatively use the Command Prompt facility).
Type: net stop w32time && net start w32time
Then press enter.

To reset the local computers’ time, type the following on all computers except for the time server which must not be synchronised with itself:
w32tm –s

To configure the Windows Time service to use an external time source, click Start, Run and type regedit then click OK.

Locate the following subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters
In the right pane, right-click Type then click Modify, in edit Value type NTP in the Value data box then click OK.

Now in the right pane, right click ReliableTimeSource, then click Modify.
In the Edit DWORD Value box, under Value Data, type 0, then click OK.

Right-click NtpServer in the right pane then click Modify.
In Edit Value, type the Domain Name System (DNS), each DNS must be unique.
Now click Ok.

For Windows 2000 Service Pack 4 only, set the time correction settings to do this locate:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters
In the right pane, right-click MaxAllowedClockErrInSecs, then Modify in the Edit DWORD Value box, , type a time in seconds max number of seconds difference between the local clock and the time received from the NTP server in order to be considered a valid new time.
Click OK.

To set the poll intervals locate:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters
In the right pane, right-click Period, then click Modify.
In the Edit DWORD Value box, under Value Data, type 24 then OK
Exit Registry Editor

Click Start, then Run then type the following and press Enter:
Net stop w32time && net start w32time

To reset the local computers’ time, type the following on all computers except for the time server which must not be synchronised with itself:

Network Time Protocol (NTP) is an Internet protocol used for the transfer of accurate time, providing time information along so that a precise time can be obtained

To enable the Network Time Protocol; NTPserver, locate and click:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpServer\
In the right pane, right-click Enabled, then click Modify.
In the Edit DWord Value box, type 1 under Value data, then click OK.

Now go back and click on
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters\NtpServer
In the right pane, right-click NtpServer, then Modify, in the Edit DWORD Value under Value Data type In the right pane, right-click NtpServer, then Modify, in the Edit DWORD Value under Value Data type the Domain Name System (DNS), each DNS must be unique and you must append 0×1 to the end of each DNS name otherwise changes will not take effect.
Now click Ok.

Locate and click the following
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient\SpecialPollInterval
In the right pane, right-click SpecialPollInterval, then click Modify.
In the Edit DWORD Value box, under Value Data, type the number of seconds you want for each poll, ie 900 will poll every 15 minutes, then click OK.

To configure the time correction settings, locate:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\config
In the right pane, right-click MaxPosPhaseCorrection, then Modify, in the Edit DWORD Value box, under Base, click Decimal, under Value Data, type a time in seconds such as 3600 (an hour) then click OK.

Now go back and click:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\config
In the right pane, right-click MaxNegPhaseCorrection, then Modify.
In the Edit DWORD box under base, click Decimal, under value data type the time in seconds you want to poll such as 3600 (polls in one hour)

Exit Registry Editor
Now to restart windows time service, click Start, Run (or alternatively use the command prompt facility) and type:
net stop w32time && net start w32time

And on each computer, other than the time server, type:
W32tm/ -s
And that’s it your time server should be now up and running.

Time synchronisation in modern computer networks is essential. It not only provides the only frame of reference between all devices, it is critical in everything from securing, planning and debugging a network to providing a time stamp for applications such as data acquisition or email.

Microsoft Windows XP has a time synchronisation utility built into the operating system called Windows Time (w32time.exe) which can be configured to operate as a network time server. It can be configured to both synchronise a network using the internal clock or an external time source.

For many applications, an internal clock can be quite adequate, although, on a network, problems can arise with applications such as sharing network files or in some environments even fraud, so it is vital for security reasons to use an accurate timing source for your network.

NTP (Network Time Protocol) is a protocol already installed on Windows XP and is used by Windows Time to keep machines synchronised to the single time source. There are several timing sources available on the Internet but Microsoft and others strongly recommend that you configure a time server with a hardware source rather than from the Internet where there is no authentication.

Specialist NTP servers are available that can receive a reliable time source via the GPS signal or specialist radio transmissions that get their time from atomic clocks.

If you wish to configure Windows XP to operate as a time server then first thing is to locate the Windows Time subkey. To do this:
Run Regedit (Click start/run/then type REGEDIT/and click enter.

Note: editing your system registry can cause problems with your system. It is advisable to back up your system before editing the registry.

Now locate the following subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\parameters\
Right click the right-hand side and click Modify. In the Edit Value box, under Value Data, type NTP and then click OK.
Now go to the Config folder and right-click AnnounceFlags, Modify and in the Edit DWORD Value box, under Value Data, type 5, and then click OK.

Locate this subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient\

Right-click in the right-side window and Modify. Edit the DWORD value box and type the number of seconds you want for each poll under Value data, i.e.: 900 will equal 15 minutes. The poll field represents the polling interval between NTP poll packets.

To enable the NTP server locate the subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpServer\
Right click enabled (in the right-hand window) then Modify. Edit the DWORD Value and type 1. Right-click NtpServer, then Modify and in the Edit DWORD Value under Value Data type Peers, then click OK.

Locate:  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\config
In the right pane, right-click MaxPosPhaseCorrection, then Modify, in the Edit DWORD Value box, under Base, click Decimal, under Value Data, type a time in seconds such as 3600 (an hour) then click OK. This adjusts the connection settings.

Now go back and click:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\config

In the right pane, right-click MaxNegPhaseCorrection, then Modify.
In the Edit DWORD box under base, click Decimal, under value data type the time in seconds you want to poll such as 3600 (an hour).

Exit Registry then restart windows time service by clicking Start/Run then typing:
net stop w32time && net start w32time.
on each computer, other than the domain controller, type: W32tm/resync/rediscover.
The time server should be now up and running.