How do I use the Windows Time Service?

If you manage Windows 2000 and Active Directory, you should know that the Win2K Time Service is key to ensuring that the Kerberos security protocol and other Windows 2000 services work correctly. All machines in a Windows 2000 forest need to have the correct time. This article will explain the details and show you how to configure and troubleshoot the Time Service. How does time synchronization work? The Windows 2000 Time Service (w32time.dll) is installed by default on all Windows 2000 computers. The Time Service starts automatically on computers that are part of a domain and can be started manually on other machines.When a computer joined to a domain is booted, the Time Service is enabled. As the Net Logon service looks for a domain controller (DC) and is authenticated, the computer sends a request to get the time and waits until the DC responds. Once it receives the time from the DC, the Time Service will perform the following:

• If the local clock is behind the current DC time, the Time Service changes the local time immediately.
• If the local clock is faster than three minutes, the Time Service changes the local time immediately.
• If the local clock is less than three minutes fast, the Time Service slows the clock down to bring it into synchronization.

The Time Service then attempts synchronization every 45 minutes until all clocks are synchronized three times. Once properly synchronized, the Time Service will resynchronize time every eight hours. If you have Active Directory (AD) configured, all other machines in your forest will synchronize to your time server, as shown in Figure A.

Before configuring the Time Service, you need to become familiar with some of the command-line tools you’’ll use to

work with it. We’’ll start with the Net Time command. In order to properly configure Net Time, you need to know the syntax. If you open a command prompt and type net time /?, you’ll see the syntax shown in Figure B.
Table A breaks down the list of options available for the Net Time command. You’’ll use this command to have one of your domain controllers synchronize to an external authority and then provide time information to the rest of the domain.

Table A

Net Time options

To display the time of a Windows 2000 machine, follow these steps:

1. From the Start menu, select Programs | Accessories | Command Prompt.
2. Type a command such as net time \\kiev, as we’’ve done in Figure C.

To set the external Simple Network Time Protocol (SNTP) time server:

1. From the Start menu, select Programs | Accessories | Command Prompt.
2. Type a command such as net time /setsntp:ntp2.usno.navy.mil, as shown in Figure D.

Here are the steps for querying the SNTP name:

1. From the Start menu, select Programs | Accessories | Command Prompt.
2. Type a command such as net time /querysntp, as shown in Figure E.

Troubleshooting the Windows 2000 Time Service

The w32tm tool is used to troubleshoot any problems that might occur during or after the configuration of the Time Service. When troubleshooting, make sure to stop the Time Service before using this tool. Not doing so will cause a port error in the Event Viewer.

Furthermore, in order for the Time Service to work properly, you will need to have port 123 opened on your firewall. Otherwise, you can’t synchronize to an external time source. To access the syntax of the troubleshooting tool, type w32tm /? from a command prompt.

Table B shows a detailed list of command options available for the W32tm command.

Table B

W32tm command options

To test the synchronization of a computer:

From the Start menu, select Programs | Accessories | Command Prompt.

1. Type net stop w32time.
2. Type w32tm –once –test –v (Figure F).

You will have to stop and start the service every time you make a change to the Time Service. You must have Administrator rights to stop and start services.

To stop the W32 Time Service:

1. From the Start menu, select Programs | Accessories | Command Prompt.
2. Type net stop w32time.

To start the W32 Time Service:

1. From the Start menu, select Programs | Accessories | Command Prompt.
2. Type net start w32time.

To stop and start the service using the Windows 2000 graphical user interface (GUI):

1. From the Start menu, select Programs | Administrative Tools | Computer Management.
2. Select Services And Applications.
3. Select Services and highlight Windows Time.
4. Right-click to stop or start the service.

I have provided you with a brief look at the Windows Time Service. For more information, you can also reference the following resources:

• The Windows 2000 Time Service
• How to Configure an Authoritative Time Server in Windows 2000
• Basic Operation of the Windows Time Service
• Windows 2000 Utilities: Taming the Time Service
• Registry Entries for the W32 Time Service
• USNO NTP Network Time Servers