For small user bases, a Microsoft Dynamics CRM server (any edition) can be deployed in a single-server configuration, with Microsoft Dynamics CRM Server 2011, SQL Server, SQL Server Reporting Services, and optionally Microsoft Exchange Server installed and running on the same computer.
Single-server deployments are not recommended for best experience in application performance and disaster recovery.
There is one limitation to single-server deployments: the server where Microsoft Dynamics CRM Server 2011 is installed cannot also function as a domain controller, unless it is running Microsoft Windows Small Business Server. If the computer is a member server (not functioning as a domain controller), you can deploy a single-server Microsoft Dynamics CRM solution on any other supported version of Windows Server.
Except for Microsoft Windows Small Business Server, Microsoft Dynamics CRM is not supported when you install it on an Active Directory directory service domain controller.