What is the use of single doamin?

Hello, I think that you want to understand what is a Windows domain: http://en.wikipedia.org/wiki/Windows_Server_domain Also, have a look to this link about the definition of Active Directory: http://en.wikipedia.org/wiki/Active_Directory This posting is provided "AS IS" with no warranties or guarantees , and confers no rights. Microsoft Student Partner Microsoft Certified Professional Microsoft Certified Systems Administrator: Security Microsoft Certified Systems Engineer: Security Microsoft Certified Technology Specialist: Windows Server 2008 Active Directory, Configuration Microsoft Certified Technology Specialist: Windows Server 2008 Network Infrastructure, Configuration

You can check this article. Also check below webcast. TechNet Webcast: Active Directory Fundamentals—Level 200 TechNet Webcast: Active Directory Inside Out (Part 1 of 11)—Active Directory Logical Concepts—Level 200 TechNet Webcast: TechNet Webcast: Active Directory Inside Out (Part 2 of 11)—Active Directory Physical Concepts—Level 200 TechNet Webcast: Active Directory Inside Out (Part 3 of 11)—Active Directory Replication and the Operations Masters Role—Level 200 Thanks