Configuring Time Service - A short explanation.

There are couple of articles available at Microsoft site for configuring Windows Time Service but the below is the gist of that whole and it might be useful for you to configure the Time Service in Windows 2000 and Windows Server 2003 Operating Systems.
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By default, only the first domain controller or so-called Root domain controller and finally so-called "PDC Emulator" is configured to be a Reliable Time Source. If it doesn't exist you need to create it to make it ReliableTimeSource for other client computers and domain controllers.
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By default client machines use *default hierarchy" to synchronize time. Clients will only sync with their own domain controllers in the domain. This is default behavior and by design and to keep time closer between all the computers.
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PDC Emulator is the 2nd highest stratum. Client will try to sync time with their own domain controller *unless* specifically you specify to do so. Because PDC Emulator is configured an authoritative server by default. It is configured using *ReliableTimeSource" entry in registry.

Stratum:
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1 � � External NTP time source
2 � � PDC emulator of the forest root domain
3 � � Domain controllers in the forest root domain or PDC emulators in child domains
4 � � Workstations and member servers in the forest root domain or domain controllers in child domains
5 � � Workstations and member servers in child domains
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Computers choose a time source according to a specific order of preference. This order, from most preferred to least preferred. The following table displays the preferences for Selecting a Time Source:
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����� Computer � � � � � � � � � � ������������� �� � � � � � � Location � ����������� ��Reliability of Time Source
1 � � Parent domain controller � � � � � � � � � � � � � � �In-site � � � � � � � � � � �Reliable
2 � � Local domain controller � � � � � � � � � � � � � � � �In-site � � � � � � � � � � �Reliable
3 � � Parent domain controller � � � � � � � � � � � � � � �In-site � � � � � � � � � � �Not reliable
4 � � Local PDC emulator������������������������������������In-site � � � � � � � � � � Not reliable
5 � � Parent domain controller����������������������������� Out-of-site � � � � � � � Reliable
6 � � Local domain controller��������������������������������Out-of-site � � � � � � � Reliable
7 � � Parent domain controller������������������������������Out-of-site � � � � � � � Not reliable
8 � � Local PDC emulator������������������������������������Out-of-site � � � � � � � �Not reliable
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There is nothing much you need to do with *ReliableTimeSource* entry in registry. Simply edit the value and set it to 1 to make it Reliable time source for all computers in your network.
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Moreover, you can also configure your PDC or Root Domain Controller to sync with hardware as a source time server but it is recommended that you configure your PDC to sync with an external time source.
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Below article explain more about how to configure the servers for Time Service.
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How to configure an Authoritative Time server in Windows 2000:

http://support.microsoft.com/kb/q216734/
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