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Services Utility: Windows Time Service

Display Name (?): Windows Time
Short Name (?): W32Time
Executable (?): svchost.exe
Library (?): w32time.dll
Depends On (?): None.
Supports (?): None.
Description (?): Maintains date and time synchronization on all clients and servers in the network. If this service is stopped, date and time synchronization will be unavailable. If this service is disabled, any services that explicitly depend on it will fail to start.
OS (?): XP Home/Professional, Vista Home/Business, NT4 Server, 2000 Server, Server 2003, Vista Server
Startup (?):

Explanation (?):

The Windows time service is used in syncronizing your computer's clock with that of another computer on a specific time interval using the Network Time Protocol (NTP) that uses port 123. This service is by default configured to syncronize the time with the local domain, but this is only useful if you are on a corporate / business network. If you are a home user you can configure this service to connect with an external computer that supports NTP.

If you wish to use this service then servers you can use to syncronize to can be found at the National Institute of Standards and Technology (NIST) Time Physics Laboratory. Their servers are government owned atomic clocks at varying locations around the world and are accurate to your latency time to them. Their website itself is located at and a Windows 32 application that you manually use is located there as well as the name servers you can use in configuring the Windows Time service.

Setting Windows to use an external server is fairly simple, but requires either setting it through the registry or the command line. If you set it through the registry you will need to restart the Windows Time service whereas the command line will immediately use it the next time period.

From the commandline you will need to use the NET TIME command. To change the time to an external server use 'NET TIME /setsntp:{IP}' where {IP} is the IP of the computer you wish to syncronize with. If you wish to syncronize with a computer on the local network you can use the NetBIOS name like 'NET TIME \\{NetBIOS_NAME}' where {NetBIOS_Name} is the name of the computer. You can also use this command to syncronize with a domain using 'NET TIME /domain:{domain_name}' where {domain_name} is the name of the domain that you wish to syncronize to.

The registry way is a bit trickier if you are not experienced with it. If you have never modified your registry before then it is highly recommended you study the procedure of modifying it before attempting to do this. This is by no means a comprehensive guide to the Windows Time service and only covers a few of the entries for it.
PATH: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters
+ LocalNTP (DWORD) - Set this to 1 to use the local machine as an NTP server. Any other value means it isn't.
+ Log (DWORD) - Set this to 1 to write to the system log when the system time is syncronize through the Windows Time service.
+ NTPServer (REG_SZ) - Set this to the IP address you wish to syncronize with.
+ Period (REG_SZ) - This is the update period of the Windows Time service. The interval is in the number of times to update daily.
+ PrimarySource (REG_SZ) - This is a list of all NetBIOS names to syncronize to. Each name must be prefixed with two backslashed (\\) and be separated by semicolons (;).
+ Type (REG_SZ) - Sets the update type to either use NTP that uses the LocalNTP keyname or Primary to use the PrimarySource keyname.

I would generally recommend using this service to syncronize your system clock as it will help to keep your time accurate. If you wish to use it be sure to set it up to use an NTP server if you're just a home user or to use a domain on a corporate network. Set this service to disabled if you wish to save resources. Also, be sure to set the frequency to once a day if using an Internet service as it is rude to poll them more often.

Please visit /tools/services/ for the complete Services utility.