Windows Time service tools and settings
The Windows Time service (W32Time) synchronizes the date and time for all computers managed by Active Directory Domain Services (AD DS). This article covers the different tools and settings used to manage the Windows Time service.
By default, a computer that is joined to a domain synchronizes time through a domain hierarchy of time sources. However, if a computer has been manually configured to synchronize from a specific time source, perhaps because it was formerly not joined to a domain, you can reconfigure the computer to begin automatically sourcing its time from the domain hierarchy.
Most domain-joined computers have a time client type of NT5DS, which means that they synchronize time from the domain hierarchy. An exception to this is the domain controller, which functions as the primary domain controller (PDC) emulator operations master for the root forest domain. The PDC emulator operations master in turn is configured to synchronize time with an external time source.
You can achieve down to one-millisecond time accuracy in your domain. For more information, see Support boundary for high-accuracy time and Accurate Time for Windows Server 2016.
Caution
Don't use the Net time command to configure or set a computer's clock time when the Windows Time service is running.
Also, on older computers that run Windows XP or earlier, the Net time /querysntp command displays the name of a Network Time Protocol (NTP) server with which a computer is configured to synchronize, but that NTP server is used only when the computer's time client is configured as NTP or AllSync. This command has since been deprecated.
Network port
The Windows Time service follows the Network Time Protocol (NTP) specification, which requires the use of UDP port 123 for all time synchronization. Whenever the computer synchronizes its clock or provides time to another computer, it happens over UDP port 123. This port is reserved by the Windows Time service as the destination port.
Note
- NTP Servers typically listen on UDP port 123 for requests and respond from the same port, which is also true for the inbox W32Time NTP Server.
- Inbox W32Time NTP Client and NTP Server can be enabled or disabled independently and both share UDP port 123 for their functions.
- Inbox W32Time NTP Client can only use UDP 123 as the source port.
- If you have a computer with multiple network adapters (is multi-homed), you cannot enable the Windows Time service based on a network adapter.
Command-line parameters for W32Time
You can use the w32tm command to configure Windows Time service settings and diagnose computer time problems. W32tm is the preferred command-line tool for configuring, monitoring, and troubleshooting the Windows Time service. Membership in the local Administrators group is required to run this tool locally and membership in the Domain Admins group is required to run this tool remotely.
To use w32tm, perform the following:
- Click Start > type cmd > right-click Command Prompt > select Run as administrator.
- At the command prompt, enter w32tm followed by the applicable parameters.
| Parameter | Description |
|---|---|
| /? | Displays the w32tm command-line help |
| /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 Windows 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 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):
/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.
/largephaseoffset:<milliseconds>: Sets the time difference between local and network time that W32Time will consider a spike. |
| /debug {/disable | {/enable /file:<name> /size:/<bytes> /entries:<value> [/truncate]}} | Enables or disables the local computer Windows Time service private log. This parameter was first made available for the Windows Time client in Windows Vista and Windows Server 2008. /disable: Disables the private log. /enable: Enables the private log.
/truncate: Truncate the file if it exists. |
| /dumpreg [/subkey:<key>] [/computer:<target>] | Displays the values associated with a given registry key. The default key is HKLM\System\CurrentControlSet\Services\W32Time (the root key for the Windows Time service). /subkey:<key>: Displays the values associated with subkey <key> of the default key. /computer:<target>: Queries registry settings for computer <target>. |
| /monitor [/domain:<domain name>] [/computers:<name>[,<name>[,<name>...]]] [/threads:<num>] | Monitors the Windows Time service. /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's 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. The allowed range is 1-50. |
| /ntpte <NTP time epoch> | Converts an NTP time (measured in 2-32-second intervals starting from 0h 1-Jan 1900) into a readable format. |
| /ntte <NT time epoch> | Converts a Windows NT system time (measured in 10-7-second intervals starting from 0h 1-Jan 1601) into a readable format. |
| /query [/computer:<target>] {/source | /configuration | /peers | /status} [/verbose] | Displays the computer's Windows Time service information. This parameter was first made available for the Windows Time client in Windows Vista and Windows Server 2008. /computer:<target>: Queries the information of <target>. If not specified, the default value is the local computer. /source: Displays the time source. /configuration: Displays the configuration of run time and where the setting comes from. In verbose mode, display the undefined or unused setting too. /peers: Displays a list of peers and their status. /status: Displays Windows Time service status. /verbose: Sets the verbose mode to display more information. |
| /register | Registers the Windows Time service to run as a service and adds its default configuration information to the registry. |
| /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. The NTP client requires UDP 123 as the source port. /computer:<computer>: Specifies the computer that should resynchronize. If not specified, the local computer resynchronizes. /nowait: don't wait for resynchronization to occur; return immediately. Otherwise, wait for resynchronization to complete before returning. /rediscover: Redetects the network configuration and rediscovers network sources, then resynchronizes. /soft: Resynchronizes by using existing error statistics. This is used for compatibility purposes. |
| /stripchart /computer:<target> [/period:<refresh>] [/dataonly] [/samples:<count>] [/rdtsc] | Displays a strip chart of the offset between this computer and another computer. The NTP client uses ephemeral UDP source port to communicate to the server to prevent conflicts with the inbox NTP client. /computer:<target>: The computer to measure the offset against. /period:<refresh>: The time between samples, in seconds. The default is 2 seconds. /dataonly: Displays the data only, without graphics. /samples:<count>: Collects <count> samples, then stops. If not specified, samples are collected until Ctrl+C is pressed.
|
| /tz | Displays the current time zone settings. |
| /unregister | Unregisters the Windows Time service and removes all of its configuration information from the registry. |
Set the client to use two time servers
To set a client computer to point to two different time servers, one named ntpserver.contoso.com and another named clock.adatum.com, run the following:
w32tm /config /manualpeerlist:"ntpserver.contoso.com clock.adatum.com" /syncfromflags:manual /update
Set the client to sync time automatically from a domain source
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:
w32tm /config /syncfromflags:domhier /update
net stop w32time
net start w32time
Check the client time configuration
To check a client configuration from a Windows-based client computer that has a host name of contosoW1, run the following command:
w32tm /query /computer:contosoW1 /configuration
The output of this command displays a list of W32Time configuration parameters that are set for the client.
Since Windows Server 2016, there has been improvement to 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 deprioritize one of them. For example, if you want to prioritize ntpserver.contoso.com over clock.adatum.com, run the following command:
w32tm /config /manualpeerlist:"ntpserver.contoso.com,0x8 clock.adatum.com,0x2" /syncfromflags:manual /update
Additionally, you can run the following command and read the value of NtpServer in the output:
reg query HKLM\SYSTEM\CurrentControlSet\Services\W32Time\Parameters
Configure computer clock reset
In order for w32tm to reset a computer clock, it first checks the offset CurrentTimeOffset, also known as Phase Offset, between the current time and the computer clock time to determine whether the offset is less than the MaxAllowedPhaseOffset value.
CurrentTimeOffset≤MaxAllowedPhaseOffset: Adjust the computer clock gradually by using the clock rate.CurrentTimeOffset>MaxAllowedPhaseOffset: Set the computer clock immediately.
Then, to adjust the computer clock by using the clock rate, w32tm calculates a PhaseCorrection value. This algorithm varies depending on the version of Windows:
Windows Server 2016 and later versions:
PhaseCorrection_raw= (CurrentTimeOffset) ÷ (16 ×PhaseCorrectRate×pollIntervalInSeconds)MaximumCorrection= (CurrentTimeOffset) ÷ (UpdateInterval÷ 100)PhaseCorrection= min(PhaseCorrection_raw,MaximumCorrection)Windows Server 2012 R2 and earlier versions:
To get the
SystemClockRatevalue, you can use the following command and convert it from seconds to clock ticks by using the formula of (seconds × 1,000 × 10,000):PhaseCorrection= (CurrentTimeOffset) ÷ (PhaseCorrectRate×UpdateInterval)
All versions of Windows use the same final equation to check PhaseCorrection:
PhaseCorrection ≤ SystemClockRate ÷ 2
Note
Windows Server 2019 and Windows 10 1809 have the same formula as Windows Server 2016 and later versions described above by applying cumulative updates from KB5006744 onwards.
These equations use PhaseCorrectRate, UpdateInterval, MaxAllowedPhaseOffset, and SystemClockRate measured in units of clock ticks. On Windows systems, 1 ms = 10,000 clock ticks.
MaxAllowedPhaseOffset is configurable in the registry. However, the registry parameter is measured in seconds instead of clock ticks.
To see the SystemClockRate and pollIntervalInSeconds values (measured in seconds), open a Command Prompt window and then run w32tm /query /status /verbose. This command produces an output that resembles the following:
Leap Indicator: 0(no warning)
Stratum: 1 (primary reference - syncd by radio clock)
Precision: -23 (119.209ns per tick)
Root Delay: 0.0003538s
Root Dispersion: 0.0100002s
ReferenceId: 0x00000000 (unspecified)
Last Successful Sync Time: 5/23/2023 7:51:39 PM
Source: VM IC Time Synchronization Provider
Poll Interval: 6 (64s)
Phase Offset: -0.0000013s
ClockRate: 0.0156250s
State Machine: 2 (Sync)
Time Source Flags: 3 (Authenticated Hardware )
Server Role: 0 (None)
Last Sync Error: 0 (The command completed successfully.)
Time since Last Good Sync Time: 15.7344985s
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:
(value in seconds) × 1,000 × 10,000
For example, if SystemClockRate is 0.0156250 seconds, the value that the equation uses is 156,250 clock ticks. The following examples show how to apply these calculations for Windows Server 2012 R2 and earlier versions.
System clock rate is off by four minutes
Your computer clock time is 11:05 and the actual current time is 11:09:
PhaseCorrectRate = 1
UpdateInterval = 30,000 clock ticks
SystemClockRate = 156,000 clock ticks
MaxAllowedPhaseOffset = 10 min = 600 seconds = 600 × 1,000 × 10,000 = 6,000,000,000 clock ticks
CurrentTimeOffset = 4 min = 4 × 60 × 1,000 × 10,000 = 2,400,000,000 clock ticks
Is CurrentTimeOffset ≤ MaxAllowedPhaseOffset?
2,400,000,000 ≤ 6,000,000,000 = True
Does it satisfy the following equation?
(CurrentTimeOffset) ÷ (PhaseCorrectRate × UpdateInterval) ≤ SystemClockRate ÷ 2
2,400,000,000 ÷ (30,000 × 1) ≤ 156,000 ÷ 2
80,000 ≤ 78,000 = False
Therefore, w32tm would set the clock back immediately.
Note
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.
System clock rate is off by three minutes
Your computer clock time is 11:05 and the actual current time is 11:08:
PhaseCorrectRate = 1
UpdateInterval = 30,000 clock ticks
SystemClockRate = 156,000 clock ticks
MaxAllowedPhaseOffset = 10 min = 600 seconds = 600 × 1,000 × 10,000 = 6,000,000,000 clock ticks
CurrentTimeOffset = 3 mins = 3 × 60 × 1,000 × 10,000 = 1,800,000,000 clock ticks
Is CurrentTimeOffset ≤ MaxAllowedPhaseOffset?
1,800,000,000 ≤ 6,000,000,000 = True
Does it satisfy the following equation?
(CurrentTimeOffset) ÷ (PhaseCorrectRate × UpdateInterval) ≤ SystemClockRate ÷ 2
(1,800,000,000) ÷ (1 × 30,000) ≤ 156,000 ÷ 2
60,000 ≤ 78,000 = True
In this case, the clock is set back slowly.
Using Local Group Policy Editor
The Windows Time service stores several configuration properties as registry entries. You can use Group Policy Objects (GPOs) in Local Group Policy Editor to configure most of this information. For example, you can use GPOs to configure a computer to be an NTPServer or NTPClient, configure the time synchronization mechanism, or configure a computer to be a reliable time source. Group Policy settings for the Windows Time service can be applied to domain controllers starting with Windows Server 2003 and future iterations.
Windows stores the Windows Time service policy information in the Local Group Policy Editor under Computer Configuration\Administrative Templates\System\Windows Time Service. 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.
The following table lists the policies that you can configure for the Windows Time service and registry subkey equivalents that those policies affect.
| Group Policy | Registry locations1, 2 |
|---|---|
| Global Configuration Settings | W32Time W32Time\Config W32Time\Parameters |
| Time Providers\Configure Windows NTP Client | W32Time\TimeProviders\NtpClient |
| Time Providers\Enable Windows NTP Client | W32Time\TimeProviders\NtpClient |
| Time Providers\Enable Windows NTP Server | W32Time\TimeProviders\NtpServer |
1 Subkey: HKLM\SOFTWARE\Policies\Microsoft
2 Subkey: HKLM\SYSTEM\CurrentControlSet\Services\W32Time
Note
When you remove a Group Policy setting, Windows removes the corresponding entry from the policy area of the registry.
GPO default settings for W32Time
Below you'll find the default values for the Global Configuration Settings once enabled.
| Group Policy setting | Default value |
|---|---|
| AnnounceFlags | 10 |
| EventLogFlags | 2 |
| FrequencyCorrectRate | 4 |
| HoldPeriod | 5 |
| LargePhaseOffset | 50,000,000 |
| LocalClockDispersion | 10 |
| MaxAllowedPhaseOffset | 300 |
| MaxNegPhaseCorrection | 172,800 (48 hours) |
| MaxPollInterval | 10 |
| MaxPosPhaseCorrection | 172,800 (48 hours) |
| MinPollInterval | 6 |
| PhaseCorrectRate | 7 |
| PollAdjustFactor | 5 |
| SpikeWatchPeriod | 900 |
| UpdateInterval | 100 (1 second) |
GPO settings for NTP Client
These are the default Windows NTP client settings contained in Computer Configuration\Administrative Templates\System\Windows Time Service\Time Providers\Configure Windows NTP Client.
| Group Policy setting | Default value |
|---|---|
| NtpServer | time.windows.com, 0x9 |
| Type | NT5DS - Used for domain-joined computers NTP - Used for non-domain-joined computers |
| CrossSiteSyncFlags | 2 |
| ResolvePeerBackoffMinutes | 15 |
| ResolvePeerBackoffMaxTimes | 7 |
| SpecialPollInterval | 1024 |
| EventLogFlags | 0 |
Note
If you use Group Policy to set the NtpServer value as part of the Configure Windows NTP Client policy and apply it to a domain member, the Windows Time Service will not use the NtpServer Registry value. To view your NTP configuration, open a Command Prompt and run w32tm /query /configuration.
Windows Time registry reference
The Windows Time service stores information under the following registry paths:
HKLM\SYSTEM\CurrentControlSet\Services\W32Time
HKLM\SYSTEM\CurrentControlSet\Services\W32Time\Config
HKLM\SYSTEM\CurrentControlSet\Services\W32Time\Parameters
HKLM\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient
HKLM\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpServer
Warning
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:
- 1 minute = 60 sec
- 1 sec = 1000 ms
- 1 ms = 10,000 clock ticks on a Windows system, as described in DateTime.Ticks Property.
For example, 5 minutes becomes 5 × 60 × 1000 × 10000 = 3,000,000,000 clock ticks.
In the following section, "All versions" refers to Windows 7, including future iterations, and Windows Server 2008 including future iterations.
| Registry entry | Versions | Description |
|---|---|---|
| AnnounceFlags | All versions | Controls whether this computer is marked as a reliable time server. A computer isn't marked as reliable unless it's also marked as a time server.
The default value for domain members is 10. The default value for stand-alone clients and servers is 10. |
| ClockAdjustmentAuditLimit | Windows Server 2016 Version 1709 and later versions; Windows 10 Version 1709 and later versions | Specifies the smallest local clock adjustments that may be logged to the W32Time service event log on the target computer. The default value is 800 (parts per million - PPM). |
| ClockHoldoverPeriod | Windows Server 2016 Version 1709 and later versions; Windows 10 Version 1709 and later versions | Indicates the maximum number of seconds a system clock can nominally hold its accuracy without synchronizing with a time source. If this period of time passes without W32Time obtaining new samples from any of its input providers, W32Time initiates a rediscovery of time sources. Default: 7,800 seconds. |
| EventLogFlags | All versions | Controls which events that the time service logs.
The default value on domain members is 2. The default value on stand-alone clients and servers is 2. |
| FrequencyCorrectRate | All versions | 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. Zero isn't a valid value for the FrequencyCorrectRate registry entry. On Windows Server 2003, Windows Server 2003 R2, Windows Server 2008, and Windows Server 2008 R2 computers, if the value is set to 0, the Windows Time service automatically changes it to 1. |
| 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 several seconds, and is 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 is 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. |
| LocalClockDispersion | All versions | 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 | 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 300. The default value for stand-alone clients and servers is 1. |
| MaxClockRate | All versions | 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 | 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. The value 0xFFFFFFFF is a special case. This value means that the service always corrects the time. The default value for domain members is 0xFFFFFFFF (hexadecimal). The default value for domain controllers is 172,800 (48 hrs). The default value for stand-alone clients and servers is 54,000 (15 hrs). |
| MaxPollInterval | All versions | Specifies the largest interval, in log base 2 seconds, allowed for the system polling interval. 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 | All versions | 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. The value 0xFFFFFFFF is a special case. This value means that the service always corrects the time. The default value for domain members is 0xFFFFFFFF (hexadecimal). The default value for domain controllers is 172,800 (48 hrs). The default value for stand-alone clients and servers is 54,000 (15 hrs). |
| MinClockRate | All versions | 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 | All versions | Specifies the smallest interval, in log base 2 seconds, allowed for the system polling interval. A system doesn't 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. |
| 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. Zero isn't a valid value for the PhaseCorrectRate registry entry. On Windows Server 2003, Windows Server 2003 R2, Windows Server 2008, and Windows Server 2008 R2 computers, if the value is set to 0, the Windows Time service automatically changes it to 1. |
| 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. The default value on domain members is 5. The default value on stand-alone clients and servers is 5. |
| SpikeWatchPeriod | All versions | Specifies the amount of time that a suspicious offset must persist before it's accepted as correct (in seconds). The default value on domain members is 900. The default value on stand-alone clients and workstations is 900. |
| TimeJumpAuditOffset | All versions | An unsigned integer that indicates the time jump audit threshold, in seconds. If the time service adjusts the local clock by setting the clock directly, and the time correction is more than this value, then the time service logs an audit event. |
| UpdateInterval | All versions | 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. Zero isn't a valid value for the UpdateInterval registry entry. On computers running Windows Server 2003, Windows Server 2003 R2, Windows Server 2008, and Windows Server 2008 R2, if the value is set to 0, the Windows Time service automatically changes it to 1. |
| UtilizeSslTimeData | Windows versions later than Windows 10 build 1511 | Value of 1 indicates that W32Time uses multiple SSL timestamps to seed a clock that is grossly inaccurate. Note: UtilizeSslTimeData is the Registry Value that refers to Secure Time Seeding. To learn more, see Secure Time Seeding – improving time keeping in Windows. |
Enhanced logging
The following registry entries aren't part of the W32Time default configuration but can be added to the registry to obtain enhanced logging capabilities. The information logged to the System Event log can be modified by changing values for the EventLogFlags setting in the Group Policy Object Editor. By default, the Windows Time service logs an event every time that it switches to a new time source.
In order to enable enhanced W32Time logging, add the following registry entries into HKLM\SYSTEM\CurrentControlSet\Services\W32Time\Config.
| Entry | Versions | Description |
|---|---|---|
| FileLogEntries | All versions | Controls the number of entries created in the Windows Time log file. The default value is none, which doesn't log any Windows Time activity. Valid values are 0 to 300. This value doesn't affect the event log entries normally created by Windows Time. |
| FileLogName | All versions | Controls the location and file name of the Windows Time log. The default value is blank, and shouldn't 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 doesn't affect the event log entries normally created by Windows Time. |
| FileLogSize | All versions | Controls the circular logging behavior of Windows Time log files. When FileLogEntries and FileLogName are defined, so is the size in bytes to allow the log file to reach before overwriting the oldest log entries with new entries. Use 1000000 or larger value for this setting. This value doesn't affect the event log entries normally created by Windows Time. |