Network Administration: Windows Server Default Groups

Windows Server 2008 comes with a number of predefined groups that you can use. Although you shouldn’t be afraid to create your own groups when you need them, there’s no reason to create your own group if you find a default group that meets your needs.

Some of these groups are listed in the Builtin container in the Active Directory Users and Computers management console. Others are found in the Users container.

Default Groups Located in the Builtin Container

Group	Description
Account Operators	This group is for users who should be allowed to create, edit, or delete user accounts but shouldn’t be granted full administrator status.
Administrators	These are the system administrators who have full control over the domain. The Administrator account is a default member of this group. You should create only a limited number of accounts that belong to this group.
Backup Operators	This group is for users who need to perform backup operations. Because this group must have access to the files that are backed up, it presents a security risk. So you should limit the number of users that you add to this group.
Guests	This group allows members to log on, but little else. The default Guest account is a member of this group.
Network Configuration	This group is allowed to twiddle with network configuration settings, including releasing and renewing DHCP leases.
Print Operators	This group grants users access to printers, including the ability to create and share new printers and manage print queues.
Remote Desktop Users	This group can remotely log on to domain controllers in the domain.
Replicator	This group is required to support directory replication. Don’t add users to this group.
Server Operators	These users can log on locally to a domain controller.
Users	These users can perform common tasks, such as running applications and using local and network printers.

Default Groups Located in the Users Container

Group	Description
Cert Publishers	These users can publish security certificates for users and computers.
DnsAdmins	This group is installed if you install DNS. It grants administrative access to the DNS Server service.
DnsUpdateProxy	This group is installed if you install DNS. It allows DNS clients to perform dynamic updates on behalf of other clients, such as DHCP servers.
Domain Admins	These users have complete control of the domain. By default, this group is a member of the Administrators group on all domain controllers, and the Administrator account is a member of this group.
Domain Computers	This group contains all computers that belong to the domain. Any computer account created becomes a member of this group automatically.
Domain Controllers	This group contains all domain controllers in the domain.
Domain Guests	This group contains all domain guests.
Domain Users	This group contains all domain users. Any user account created in the domain is added to this group automatically.
Group Policy	These users can modify Group Policy for the domain.
IIS_WPG	This group is created if you install IIS. It’s required for IIS to operate properly.
RAS and IAS Servers	This group is required for RAS and IAS servers to work properly.

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Source:http://www.dummies.com/how-to/content/network-administration-windows-server-default-grou.html