Windows Time Service

Applies To: Windows Server 2008

The Windows Time service (W32time) automatically synchronizes the local computer's time with other computers on the network.

The Windows Time service architecture consists of the following components:

  • Service Control Manager
  • Windows Time Service Manager
  • Clock Discipline
  • Time providers

The Windows Time service internal time synchronization process involves the following steps:

  • Input providers request and receive time samples from configured NTP time sources.
  • These time samples are then passed to the Windows Time Service Manager, which collects all the samples and passes them to the clock discipline subcomponent.
  • The clock discipline subcomponent applies all NTP algorithms and selects the best time sample.
  • The clock discipline subcomponent adjusts the time of the system clock to the most accurate time by either adjusting the clock rate or directly changing the time.

If a computer has been designated as a time server, it can send the time on to any computer requesting time synchronization at any point in this process.

Managed Entities

The following is a list of the managed entities that are included in this managed entity:

Name Description

Time Source Peer

A time source peer is a server from which time samples are acquired. The time source for this varies, depending on whether the computer is joined to a domain in Active Directory Domain Services (AD DS) (domain heirarchy peers) or to a workgroup (manually configured peers).

Clock Manager

The Clock Manager receives updates from a peer and uses them to skew local system time within compliance.

Time Provider

A time source (also known as a time provider or an input provider) represents a source protocol for acquiring time samples. Windows includes a Network Time Protocol (NTP) time source with the Windows Time service.


The following is a list of all aspects that are part of this managed entity:

Name Description

Service Status and Configuration

The Windows Time service updates the time server configuration settings or status. Changes to configuration are implemented when the service is restarted and when the W32tm command is used with the /update switch. These configuration or status changes occur when the Windows Time service:

  • Enters a running status.
  • Sets up the log file to record operational information. The debug logging feature of the Windows Time service can be used to help troubleshoot issues.
  • Registers for network configuration change events. Computers use the network to send time samples back and forth.
  • Creates a named event, which is a shared resource that is used for synchronizing time.
  • Saves configuration settings to the registry.

Time Service Configuration

The Windows Time service loads configuration settings from the registry. Windows Time Service uses Coordinated Universal Time (UTC), which is based on an atomic time scale and is therefore independent of time zone. Time zone information is stored in the computer's registry and is added to the system time just before it is displayed to the user.

Active Directory