Server software time

If not specified, the default value is the local computer. In verbose mode, display the undefined or unused setting too. Valid values are 0 to A range of numbers is valid, in addition to single numbers, such as ,, Value is for logging all information. Set client to use two time servers To set a client computer to point to two different time servers, one named ntpserver.

To configure a client computer that is currently synchronizing time using a manually-specified computer to synchronize time automatically from the AD domain hierarchy, run the following following:. To check a client configuration from a Windows-based client computer that has a host name of contosoW1 , run the following command:. The output of this command displays a list of W32time configuration parameters that are set for the client.

Windows Server has improved the time synchronization algorithms to align with RFC specifications. Therefore, if you want to set the local time client to point to multiple peers, we recommended that you prepare three or more different time servers.

If you have only two time servers, you should specify the Ntpserver UseAsFallbackOnly flag 0x2 to de-prioritize one of them. For example, if you want to prioritize ntpserver. Additionally, you can run the following command and read the value of NtpServer in the output:. In order for W32tm. Then, to adjust the computer clock by using the clock rate, W32tm. This algorithm varies depending on the version of Windows:. MaxAllowedPhaseOffset is configurable in the registry. However, the registry parameter is measured in seconds instead of clock ticks.

This command produces output that resembles the following. The output presents the poll interval in both clock ticks and in seconds. The equations use the value measured in seconds the value in parentheses. The output presents the clock rate in seconds. To see the SystemClockRate value in clock ticks, use the following formula:.

For example, if SystemClockRate is 0. For full descriptions of the configurable parameters and their default values, see Config entries later in this article. The following examples show how to apply these calculations for Windows Server R2 and earlier versions. In this case, if you want to set the clock back slowly, you would also have to adjust the values of PhaseCorrectRate or UpdateInterval in the registry to make sure that the equation result is TRUE.

The Windows Time service stores a number of configuration properties as registry entries. It stores configuration information that the policies define in the Windows registry, and then uses those registry entries to configure the registry entries specific to the Windows Time service.

As a result, the values defined by Group Policy overwrite any pre-existing values in the Windows Time service section of the registry. Some of the preset GPO settings differ from the corresponding default Windows Time service registry entries.

Windows loads these settings into the policy area of the registry under the following subkey:. Then Windows uses the policy settings to configure the related Windows Time service registry entries under the following subkey:.

The following table lists the policies that you can configure for the Windows Time service, and the registry subkeys that those policies affect. When you remove a Group Policy setting, Windows removes the corresponding entry from the policy area of the registry. This information is provided as a reference for use in troubleshooting and validation.

Windows registry keys are used by W32Time to store critical information. Don't change these values. Modifications to the registry are not validated by the registry editor or by Windows before they are applied. If the registry contains invalid values, Windows may experience unrecoverable errors. Some of the parameters in the registry are measured in clock ticks and some are measured in seconds.

To convert the time from clock ticks to seconds, use these conversion factors:. Note Zero is not a valid value for the FrequencyCorrectRate registry entry. HoldPeriod All versions Controls the period of time for which spike detection is disabled in order to bring the local clock into synchronization quickly. A spike is a time sample indicating that time is off a number of seconds, and is usually received after good time samples have been returned consistently.

The default value on domain members is 5. The default value on stand-alone clients and servers is 5. LargePhaseOffset All versions Specifies that a time offset greater than or equal to this value in 10 -7 seconds is considered a spike. A network disruption such as a large amount of traffic might cause a spike. A spike will be ignored unless it persists for a long period of time.

The default value on domain members is The default value on stand-alone clients and servers is It contains reserved data that is used by the Windows operating system, and any changes to this setting can cause unpredictable results.

MaxAllowedPhaseOffset All versions Specifies the maximum offset in seconds for which W32Time attempts to adjust the computer clock by using the clock rate. When the offset exceeds this rate, W32Time sets the computer clock directly. The default value for domain members is The default value for stand-alone clients and servers is 1.

The default value for stand-alone clients and servers is MaxNegPhaseCorrection All versions Specifies the largest negative time correction, in seconds, that the service makes. If the service determines that a change larger than this is required, it logs an event instead. This value means that the service always corrects the time. The default value for domain controllers is , 48 hrs. The default value for stand-alone clients and servers is 54, 15 hrs.

MaxPollInterval All versions Specifies the largest interval, in log2 seconds, allowed for the system polling interval. Note that while a system must poll according to the scheduled interval, a provider can refuse to produce samples when requested to do so. The default value for domain controllers is MaxPosPhaseCorrection All versions Specifies the largest positive time correction in seconds that the service makes.

MinPollInterval All versions Specifies the smallest interval, in log base 2 seconds, allowed for the system polling interval. Note that while a system does not request samples more frequently than this, a provider can produce samples at times other than the scheduled interval. The default value for domain controllers is 6. PhaseCorrectRate All versions Controls the rate at which the phase error is corrected. Specifying a small value corrects the phase error quickly, but might cause the clock to become unstable.

If the value is too large, it takes a longer time to correct the phase error. The default value on domain members is 1. The default value on stand-alone clients and servers is 7. Note Zero is not a valid value for the PhaseCorrectRate registry entry. PollAdjustFactor All versions Controls the decision to increase or decrease the poll interval for the system. The larger the value, the smaller the amount of error that causes the poll interval to be decreased.

RequireSecureTimeSyncRequests Windows 8 and later versions Controls whether or not the DC will respond to time sync requests that use older authentication protocols. If enabled set to 1 , the DC will not respond to requests using such protocols. This is a boolean setting, and the default value is 0. SpikeWatchPeriod All versions Specifies the amount of time that a suspicious offset must persist before it is accepted as correct in seconds. The default value on stand-alone clients and workstations is All of the servers are synchronized using the same algorithm, and the accuracy of the time stamps at the server should be comparable for any one of them.

The accuracy of the time stamps as seen by a user will usually be determined largely by the stability and reciprocity of the network connection between the server and the user's systems. See the authenticated NTP description for more details.

Internet time code protocols are defined by a series of documents called Request for Comments, or RFCs. These documents are available on-line from several sites on the Internet. Large computers and workstations often include NTP software with their operating systems.

The client software runs continuously as a background task that periodically gets updates from one or more servers. The client software ignores responses from servers that appear to be sending the wrong time, and averages the results from those that appear to be correct. Many of the available NTP software clients for personal computers don't do any averaging at all. Instead, they make a single timing request to a signal server just like a Daytime or Time client and then use this information to set their computer's clock.

The data packet includes a bit timestamp containing the time in UTC seconds since January 1, with a resolution of ps. Most of the NIST time servers do not require any authentication when requesting the time in NTP format, and no keys or passwords are needed to use this service.

In addition to this standard NTP service, we also offer an authenticated version of NTP using four time servers which implement the symmetric key encryption method defined in the NTP documentation. In order to use these servers, you must apply to NIST for an encryption key, which will be linked to the network address es of your system. For more details, please see the authenticated ntp description.

The standard does not specify an exact format for the Daytime Protocol, but requires that the time is sent using standard ASCII characters.

It returns a bit unformatted binary number that represents the time in UTC seconds since January 1, Conversion to local time if necessary is the responsibility of the client program. The bit binary format can represent times over a span of about years with a resolution of 1 second.

There is no provision for increasing the resolution or increasing the range of years. The strength of the time protocol is its simplicity. Since many computers keep time internally as the number of seconds since January 1, or another date , converting the received time to the necessary format is often a simple matter of binary arithmetic.

However, the format does not allow any additional information to be transmitted, such as advance notification of leap seconds or daylight saving time, or information about the health of the server. However, the time format as specified in RFC has poor error-handling capabilities in general, and many of the client programs that use this format are poorly written and may not handle network errors properly.

Therefore users are strongly encouraged to switch to the Network Time Protocol NTP , which is more robust and provides greater accuracy. We eventually intend to phase out support for the TIME format on all servers. Another way to synchronize your computer clock is by running software that queries an Internet time server. NIST provides a free Windows program called nistimebit. Download nistimebit.

It uses your Windows time zone and daylight saving time settings, so make sure these are correct. There are several 'Help' links to explain all of the functions. Several programs have been written that can be used to synchronize a computer to NIST.

See our list of publishers of computer clock synchronization software for many different platforms. We also have an FTP site with source code for programmers who want to write their own applications.

Also the previous version ntp See the NTP changelog for details. Start installer of the Visual Studio Redistibutable package:. Visual Studio Setup is complete. It supports IPv4 only, but not IPv6. For current Windows installations the current stable NTP version should be used which also contains current security patches. Step 3a without initial configuration file : for experienced users - the configuration file must be setup manually.