Windows Time Service Tools and Settings

 

In this section

noteNota
This topic contains information only about tools and settings for Windows Time service (W32Time). For more information about how to configure the Windows Time Service, see the following topics:

If you are implementing a new domain controller or external time device to handle time synchronization, see Configuring a time source for the forest (http://go.microsoft.com/fwlink/?LinkId=111146).

Windows Time Service Tools

The following tools are associated with the Windows Time service.

W32tm.exe: Windows Time

Category

This tool is installed as part of Windows XP and Windows Server 2003 default installations.

Version compatibility

This tool works on Windows XP and Windows Server 2003.

W32tm.exe is used to configure Windows Time service settings. It can also be used to diagnose problems with the time service. W32tm.exe is the preferred command line tool for configuring, monitoring, or troubleshooting the Windows Time service.

The following tables describe the parameters used with W32tm.exe.

W32tm.exe Primary Parameters

 

Parameter Description

W32tm /?

W32tm command line help

W32tm /register

Registers the time service to run as a service and adds default configuration to the registry.

W32tm /unregister

Unregisters the time service and removes all configuration information from the registry.

w32tm /monitor

[/domain:<domain name>] [/computers:<name>[,<name>[,<name>...]]] [/threads:<num>]

domain – specifies which domain to monitor. If no domain name is given, or neither the domain nor computers option is specified, the default domain is used. This option might be used more than once.

computers – monitors the given list of computers. Computer names are separated by commas, with no spaces. If a name is prefixed with a ‘*’, it is treated as a PDC. This option might be used more than once.

threads – specifies the number of computers to analyze simultaneously. The default value is 3. Allowed range is 1-50.

w32tm /ntte <NT time epoch>

Convert an NT system time, in (10^-7)s intervals from 0h 1-Jan 1601, into a readable format.

w32tm /ntpte <NTP time epoch>

Convert an NTP time, in (2^-32)s intervals from 0h 1-Jan 1900, into a readable format.

w32tm /resync

[/computer:<computer>]

[/nowait]

[/rediscover]

[/soft]

Tells a computer that it should resynchronize its clock as soon as possible, throwing out all accumulated error statistics.

computer:<computer> – Specifies the computer that should resynchronize. If not specified, the local computer will resynchronize.

nowait – do not wait for the resynchronize to occur; return immediately. Otherwise, wait for the resynchronize to complete before returning.

rediscover – Redetect the network configuration and rediscover network sources, then resynchronize.

soft – resynchronize utilizing existing error statistics. Not useful, provided for compatibility.

w32tm /stripchart

/computer:<target>

[/period:<refresh>]

[/dataonly]

[/samples:<count>]

Display a strip chart of the offset between this computer and another computer.

computer:<target> – the computer to measure the offset against.

period:<refresh> – the time between samples, in seconds. The default is 2s.

dataonly – display only the data without graphics.

samples:<count> – collect <count> samples, then stop. If not specified, samples will be collected until Ctrl+C is pressed.

w32tm /config

[/computer:<target>]

[/update]

[/manualpeerlist:<peers>]

[/syncfromflags:<source>]

[/LocalClockDispersion:<seconds>]

[/reliable:(YES|NO)]

[/largephaseoffset:<milliseconds>]

computer:<target> – adjusts the configuration of <target>. If not specified, the default is the local computer.

update – notifies the time service that the configuration has changed, causing the changes to take effect.

manualpeerlist:<peers> – sets the manual peer list to <peers>, which is a space-delimited list of DNS and/or IP addresses. When specifying multiple peers, this option must be enclosed in quotes.

syncfromflags:<source> – sets what sources the NTP client should synchronize from. <source> should be a comma separated list of these keywords (not case sensitive):

MANUAL – include peers from the manual peer list.

DOMHIER – synchronize from a domain controller (DC) in the domain hierarchy.

LocalClockDispersion:<seconds> – configures the accuracy of the internal clock that W32Time will assume when it can’t acquire time from its configured sources.

reliable:(YES|NO) – set whether this computer is a reliable time source.

This setting is only meaningful on domain controllers.

YES – this computer is a reliable time service.

NO – this computer is not a reliable time service.

largephaseoffset:<milliseconds> – sets the time difference between local and network time which W32Time will consider a spike.

w32tm /tz

Display the current time zone settings.

w32tm /dumpreg

[/subkey:<key>]

[/computer:<target>]

Display the values associated with a given registry key.

The default key is HKLM\System\CurrentControlSet\Services\W32Time

(the root key for the time service).

subkey:<key> – displays the values associated with subkey <key> of the default key.

computer:<target> – queries registry settings for computer <target>

For more information about W32tm.exe, see Help and Support Center in Windows XP or Windows Server 2003.

Windows Time Service Registry Entries

The following registry entries are associated with the Windows Time service.

This information is provided as a reference for use in troubleshooting or verifying that the required settings are applied. It is recommended that you do not directly edit the registry unless there is no other alternative. Modifications to the registry are not validated by the registry editor or by Windows before they are applied, and as a result, incorrect values can be stored. This can result in unrecoverable errors in the system.

When possible, use Group Policy or other Windows tools, such as Microsoft Management Console (MMC), to accomplish tasks rather than editing the registry directly. If you must edit the registry, use extreme caution.

Many registry entries for the Windows Time service are the same as the Group Policy setting of the same name. The Group Policy settings correspond to the registry entries of the same name located in:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\.

There are several registry keys at this registry location. The Windows Time settings are stored in values across all of these keys.

Note

  • Many of the values in the W32Time section of the registry are used internally by W32Time to store information. These values should not be manually changed at any time. Do not modify any of the settings in this section unless you are familiar with the setting and are certain that the new value will work as expected.

The following registry entries are located under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\

AllowNonstandardModeCombinations

Registry path

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

Version

Windows XP and Windows Server 2003

This entry indicates that non-standard mode combinations are allowed in synchronization between peers. The default value for domain members is 1. The default value for stand-alone clients and servers is 1.

AllowNonstandardModeCombinations

Registry path

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

Version

Windows XP and Windows Server 2003

This entry indicates that non-standard mode combinations are allowed in synchronization between clients and servers. The default value for domain members is 1. The default value for stand-alone clients and servers is 1.

AnnounceFlags

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows XP and Windows Server 2003

This entry controls whether this computer is marked as a reliable time server. A computer is not marked as reliable unless it is also marked as a time server.

  • 0x00 Not a time server
  • 0x01 Always time server
  • 0x02 Automatic time server
  • 0x04 Always reliable time server
  • 0x08 Automatic reliable time server

The default value for domain members is 10. The default value for stand-alone clients and servers is 10.

CompatibilityFlags

Registry path

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

Version

Windows XP and Windows Server 2003

This entry specifies the following compatibility flags and values:

  • DispersionInvalid: 0x00000001
  • IgnoreFutureRefTimeStamp: 0x00000002
  • AutodetectWin2K: 0x80000000
  • AutodetectWin2KStage2: 0x40000000

The default value for domain members is 0x80000000. The default value for stand-alone clients and servers is 0x80000000.

CrossSiteSyncFlags

Registry path

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

Version

Windows XP and Windows Server 2003

This entry determines whether the service chooses synchronization partners outside the domain of the computer. The options and values are:

  • None: 0
  • PdcOnly: 1
  • All: 2

This value is ignored if the NT5DS value is not set. The default value for domain members is 2. The default value for stand-alone clients and servers is 2.

DllName

Registry path

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

Version

Windows XP and Windows Server 2003

This entry specifies the location of the DLL for the time provider.

The default location for this DLL on both domain members and stand-alone clients and servers is windir\System32\W32Time.dll.

DllName

Registry path

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

Version

Windows Server 2003

This entry specifies the location of the DLL for the time provider.

The default location for this DLL on both domain members and stand-alone clients and servers is windir \System32\W32Time.dll.

Enabled

Registry path

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

Version

Windows XP and Windows Server 2003

This entry indicates if the NtpClient provider is enabled in the current Time Service.

  • Yes 1
  • No 0

The default value on domain members is 1. The default value on stand-alone clients and servers is 1.

Enabled

Registry path

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

Version

Windows XP and Windows Server 2003

This entry indicates if the NtpServer provider is enabled in the current Time Service.

  • Yes 1
  • No 0

The default value on domain members is 1. The default value on stand-alone clients and servers is 1.

EventLogFlags

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows XP and Windows Server 2003

This entry controls the events that the time service logs.

  • Time Jump: 0x1
  • Source Change: 0x2

The default value on domain members is 2. The default value on stand-alone clients and servers is 2.

EventLogFlags

Registry path

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

Version

Windows XP and Windows Server 2003

This entry specifies the events logged by the Windows Time service.

  • 0x1 reachability changes
  • 0x2 large sample skew (This is applicable to Windows Server 2003 only)

The default value on domain members is 0x1. The default value on stand-alone clients and servers is 0x1.

FrequencyCorrectRate

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows XP and Windows Server 2003

This entry controls the rate at which the clock is corrected. If this value is too small, the clock is unstable and overcorrects. If the value is too large, the clock takes a long time to synchronize. The default value on domain members is 4. The default value on stand-alone clients and servers is 4.

Note

  • 0 is an invalid value for the FrequencyCorrectRate registry entry. On Windows Server 2003 computers, if the value is set to 0 the Windows Time service will automatically change it to 1.

HoldPeriod

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows XP and Windows Server 2003

This entry 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.

InputProvider

Registry path

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

Version

Windows XP and Windows Server 2003

This entry indicates if the NtpClient provider is enabled.

  • Yes 1
  • No 0

The default value on domain members is 1. The default value on stand-alone clients and servers is 1.

InputProvider

Registry path

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

Version

Windows XP and Windows Server 2003

This entry indicates if the NtpServer provider is enabled.

  • Yes 1
  • No 0

The default value on domain members is 1. The default value on stand-alone clients and servers is 1.

LargePhaseOffset

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows XP and Windows Server 2003

This entry 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 50000000. The default value on stand-alone clients and servers is 50000000.

LargeSampleSkew

Registry path

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

Version

Windows Server 2003

This entry specifies the large sample skew for logging in seconds. To comply with Security and Exchange Commission (SEC) specifications, this should be set to three seconds. Events will be logged for this setting only when EventLogFlags is explicitly configured for 0x2 large sample skew. The default value on domain members is 3. The default value on stand-alone clients and servers is 3.

LastClockRate

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows XP and Windows Server 2003

This entry is maintained by W32Time. It contains reserved data that is used by the Windows operating system, and any changes to this setting can cause unpredictable results. The default value on domain members is 156250. The default value on stand-alone clients and servers is 156250.

LocalClockDispersion

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows XP and Windows Server 2003

This entry controls the dispersion (in seconds) that you must assume when the only time source is the built-in CMOS clock. The default value on domain members is 10. The default value on stand-alone clients and servers is 10.

MaxAllowedPhaseOffset

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows XP and Windows Server 2003

This entry 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 300. The default value for stand-alone clients and servers is 1.

In order for W32Time to set the computer clock gradually, the offset must be less than the MaxAllowedPhaseOffset value and satisfy the following equation at the same time:

|CurrentTimeOffset| / (PhaseCorrectRate*UpdateInterval) < SystemClockRate / 2

MaxClockRate

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows XP and Windows Server 2003

This entry is maintained by W32Time. It contains reserved data that is used by the Windows operating system, and any changes to this setting can cause unpredictable results. The default value for domain members is 155860. The default value for stand-alone clients and servers is 155860.

MaxNegPhaseCorrection

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows XP and Windows Server 2003

This entry 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. Special case: 0xFFFFFFFF means always make time correction. The default value for domain members is 0xFFFFFFFF. The default value for stand-alone clients and servers is 54,000 (15 hrs).

MaxPollInterval

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows XP and Windows Server 2003

This entry 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 10. The default value for domain members is 15. The default value for stand-alone clients and servers is 15.

MaxPosPhaseCorrection

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows XP and Windows Server 2003

This entry specifies the largest positive 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. Special case: 0xFFFFFFFF means always make time correction. The default value for domain members is 0xFFFFFFFF. The default value for stand-alone clients and servers is 54,000 (15 hrs).

MinClockRate

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows XP and Windows Server 2003

This entry is maintained by W32Time. It contains reserved data that is used by the Windows operating system, and any changes to this setting can cause unpredictable results. The default value for domain members is 155860. The default value for stand-alone clients and servers is 155860.

MinPollInterval

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows XP and Windows Server 2003

This entry specifies the smallest interval, in log2 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. The default value for domain members is 10. The default value for stand-alone clients and servers is 10.

NtpServer

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters

Version

Windows Server 2003

This entry specifies a space-delimited list of peers from which a computer obtains time stamps, consisting of one or more DNS names or IP addresses per line. Each DNS name or IP address listed must be unique. Computers connected to a domain must synchronize with a more reliable time source, such as the official U.S. time clock.

  • 0x01 SpecialInterval
  • 0x02 UseAsFallbackOnly
  • 0x04 SymmatricActive
  • 0x08 Client

There is no default value for this registry entry on domain members. The default value on stand-alone clients and servers is time.microsoft.com,0x1.

PhaseCorrectRate

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows XP and Windows Server 2003

This entry 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

  • 0 is an invalid value for the PhaseCorrectRate registry entry. On Windows Server 2003–based computers, if the value is set to 0, the Windows Time service automatically changes it to 1.

PollAdjustFactor

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows XP and Windows Server 2003

This entry 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. The default value on domain members is 5. The default value on stand-alone clients and servers is 5.

ResolvePeerBackOffMaxTimes

Registry path

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

Version

Windows XP and Windows Server 2003

This entry specifies the maximum number of times to double the wait interval when repeated attempts to locate a peer to synchronize with fail. A value of zero means that the wait interval is always the minimum. The default value on domain members is 7. The default value on stand-alone clients and servers is 7.

ResolvePeerBackOffMinutes

Registry path

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

Version

Windows XP and Windows Server 2003

This entry specifies the initial interval to wait, in minutes, before attempting to locate a peer to synchronize with. The default value on domain members is 15. The default value on stand-alone clients and servers is 15.

ServiceDll

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters

Version

Windows XP and Windows Server 2003

This entry is maintained by W32Time. It contains reserved data that is used by the Windows operating system, and any changes to this setting can cause unpredictable results. The default location for this DLL on both domain members and stand-alone clients and servers is windir\System32\W32Time.dll.

ServiceMain

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters

Version

Windows XP and Windows Server 2003

This entry is maintained by W32Time. It contains reserved data that is used by the Windows operating system, and any changes to this setting can cause unpredictable results. The default value on domain members is SvchostEntry_W32Time. The default value on stand-alone clients and servers is SvchostEntry_W32Time.

SpecialPollInterval

Registry path

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

Version

Windows XP and Windows Server 2003

This entry specifies the special poll interval in seconds for manual peers. When the SpecialInterval 0x1 flag is enabled, W32Time uses this poll interval instead of a poll interval determine by the operating system. The default value on domain members is 3,600. The default value on stand-alone clients and servers is 604,800.

SpecialPollTimeRemaining

Registry path

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

Version

Windows Server 2003

This entry is maintained by W32Time. It contains reserved data that is used by the Windows operating system. It specifies the time in seconds before W32Time will resynchronize after the computer has restarted. Any changes to this setting can cause unpredictable results. The default value on both domain members and on stand-alone clients and servers is left blank.

SpikeWatchPeriod

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows XP and Windows Server 2003

This entry specifies the amount of time that a suspicious offset must persist before it is accepted as correct (in seconds). The default value on domain members is 900. The default value on stand-alone clients and workstations is 900.

Type

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters

Version

Windows XP and Windows Server 2003

This entry Indicates which peers to accept synchronization from:

  • NoSync. The time service does not synchronize with other sources.
  • NTP. The time service synchronizes from the servers specified in the NtpServer registry entry.
  • NT5DS. The time service synchronizes from the domain hierarchy.
  • AllSync. The time service uses all the available synchronization mechanisms.

The default value on domain members is NT5DS. The default value on stand-alone clients and servers is NTP.

UpdateInterval

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows XP and Windows Server 2003

This entry specifies the number of clock ticks between phase correction adjustments. The default value for domain controllers is 100. The default value for domain members is 30,000. The default value for stand-alone clients and servers is 360,000.

Note

  • 0 is an invalid value for the UpdateInterval registry entry. On Windows Server 2003–based computers, if the value is set to 0 the Windows Time service automatically changes it to 1.

The following three registry entries are not a part of the W32Time default configuration but can be added to the registry to obtain increased logging capabilities. The information logged to the System Event log can be modified by changing value for the EventLogFlags setting in the Group Policy Object Editor. By default, the time service creates a log in Event Viewer every time that it switches to a new time source.

The following registry entries must be added in order to enable W32Time logging:

FileLogEntries

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows Server 2003

This entry controls the amount of entries created in the Windows Time log file. The default value is none, which does not log any Windows Time activity. Valid values are 0 to 300. This value does not affect the event log entries normally created by Windows Time.

FileLogName

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows Server 2003

This entry controls the location and file name of the Windows Time log. The default value is blank, and should not be changed unless FileLogEntries is changed. A valid value is a full path and file name that Windows Time will use to create the log file. This value does not affect the event log entries normally created by Windows Time.

FileLogSize

Registry path

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config

Version

Windows Server 2003

This entry controls the circular logging behavior of Windows Time log files. When FileLogEntries and FileLogName are defined, this entry defines the size, in bytes, to allow the log file to reach before overwriting the oldest log entries with new entries. Any positive number is valid, and 3000000 is recommended. This value does not affect the event log entries normally created by Windows Time.

Windows Time Service Group Policy Settings

You can configure most W32Time parameters by using the Group Policy Object Editor. This includes configuring a computer to be an NTPServer or NTPClient, configuring the time synchronization mechanism, and configuring a computer to be a reliable time source.

Note

  • Group Policy settings for the Windows Time service can be configured on Windows Server 2003 domain controllers and can be applied only to computers running Windows Server 2003.

You can find the Group Policy settings used to configure W32Time in the Group Policy Object Editor snap-in in the following locations:

  • Computer Configuration\Administrative Templates\System\Windows Time Service
    Configure Global Configuration Settings here.
  • Computer Configuration\Administrative Templates\System\Windows Time Service\Time Providers
    Configure Windows NTP Client settings here.
    Enable Windows NTP Client here.
    Enable Windows NTP Server here.

The following table lists the global Group Policy settings that are associated with the Windows Time service and the pre-set value associated with each setting. For more information about each setting, see the corresponding registry entries in “Windows Time Service Registry Entries” earlier in this subject. The following settings are contained in a single GPO called Global Configuration Settings.

Global Group Policy Settings Associated with Windows Time

 

Group Policy Setting Pre-Set Value

AnnounceFlags

10

EventLogFlags

2

FrequencyCorrectRate

4

HoldPeriod

5

LargePhaseOffset

1280000

LocalClockDispersion

10

MaxAllowedPhaseOffset

300

MaxNegPhaseCorrection

54,000 (15 hours)

MaxPollInterval

15

MaxPosPhaseCorrection

54,000 (15 hours)

MinPollInterval

10

PhaseCorrectRate

7

PollAdjustFactor

5

SpikeWatchPeriod

90

UpdateInterval

100

The following table lists the available settings for the Configure Windows NTP Client GPO and the pre-set values that are associated with the Windows Time service. For more information about each setting, see the corresponding registry entries in “Windows Time Service Registry Entries” earlier in this subject.

NTP Client Group Policy Settings Associated with Windows Time

 

Group Policy Setting Default Value

NtpServer

time.microsoft.com,0x1

Type

Default options:

  • NTP. Use on computers that are not joined to a domain.
  • NT5DS. Use on computers that are joined to a domain.

CrossSiteSyncFlags

2

ResolvePeerBackoffMinutes

15

ResolvePeerBackoffMaxTimes

7

SpecialPollInterval

3600

EventLogFlags

0

For more information about Group Policy, see the “Group Policy Collection” in the Windows Server 2003 Technical Reference.

Network Ports Used by the Windows Time Service

Windows Time follows the NTP specification, which requires the use of UDP port 123 for all time synchronization communication. This port is reserved by Windows Time and remains reserved at all times. Whenever the computer synchronizes its clock or provides time to another computer, that communication is performed on UDP port 123.

Related Information

The following resources contain additional information that is relevant to this section.

  • RFC 1305 in the IETF RFC Database

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