What is Group Policy?

Group Policy gives you administrative control over users and computers in your network. By using Group Policy, you can define the state of a user's work environment once, and then rely on Windows Server 2003 to continually force the Group Policy settings that you apply across an entire organization or to specific groups of users and computers.

Group Policy Advantages

You can assign group policy in domains, sites and organizational units.
All users and computers get reflected by group policy settings in domain, site and organizational unit.
No one in network has rights to change the settings of Group policy; by default only administrator has full privilege to change, so it is very secure.
Policy settings can be removed and can further rewrite the changes.

Where GPO's store Group Policy Information

Group Policy objects store their Group Policy information in two locations:

Group Policy Container: The GPC is an Active Directory object that contains GPO status, version information, WMI filter information, and a list of components that have settings in the GPO. Computers can access the GPC to locate Group Policy templates, and domain controller does not have the most recent version of the GPO, replication occurs to obtain the latest version of the GPO.
Group Policy Template: The GPT is a folder hierarchy in the shared SYSVOL folder on a domain controller. When you create GPO, Windows Server 2003 creates the corresponding GPT which contains all Group Policy settings and information, including administrative templates, security, software installation, scripts, and folder redirection settings. Computers connect to the SYSVOL folder to obtain the settings.
The name of the GPT folder is the Globally Unique Identifier (GUID) of the GPO that you created. It is identical to the GUID that Active Directory uses to identify the GPO in the GPC. The path to the GPT on a domain controller is systemroot\SYSVOL\sysvol.

Managing GPOs

To avoid conflicts in replication, consider the selection of domain controller, especially because the GPO data resides in SYSVOL folder and the Active Directory. Active Directory uses two independent replication techniques to replicate GPO data among all domain controllers in the domain. If two administrator's changes can overwrite those made by other administrator, depends on the replication latency. By default the Group Policy Management console uses the PDC Emulator so that all administrators can work on the same domain controller.

WMI Filter

WMI filters is use to get the current scope of GPOs based on attributes of the user or computer. In this way, you can increase the GPOs filtering capabilities beyond the security group filtering mechanisms that were previously available.

Linking can be done with WMI filter to a GPO. When you apply a GPO to the destination computer, Active Directory evaluates the filter on the destination computer. A WMI filter has few queries that active Directory evaluates in place of WMI repository of the destination computer. If the set of queries is false, Active Directory does not apply the GPO. If set of queries are true, Active Directory applies the GPO. You write the query by using the WMI Query Language (WQL); this language is similar to querying SQL for WMI repository.

Planning a Group Policy Strategy for the Enterprise

When you plan an Active Directory structure, create a plan for GPO inheritance, administration, and deployment that provides the most efficient Group Policy management for your organization.

Also consider how you will implement Group Policy for the organization. Be sure to consider the delegation of authority, separation of administrative duties, central versus decentralized administration, and design flexibility so that your plan will provide for ease of use as well as administration.

Planning GPOs

Create GPOs in way that provides for the simplest and most manageable design -- one in which you can use inheritance and multiple links.

Guidelines for Planning GPOs

Apply GPO settings at the highest level: This way, you take advantage of Group Policy inheritance. Determine what common GPO settings for the largest container are starting with the domain and then link the GPO to this container.
Reduce the number of GPOs: You reduce the number by using multiple links instead of creating multiple identical GPOs. Try to link a GPO to the broadest container possible level to avoid creating multiple links of the same GPO at a deeper level.
Create specialized GPOs: Use these GPOs to apply unique settings when necessary. GPOs at a higher level will not apply the settings in these specialized GPOs.
Disable computer or use configuration settings: When you create a GPO to contain settings for only one of the two levels-user and computer-disable the logon and prevents accidental GPO settings from being applied to the other area.