Find the domain your computer is on
If your organization uses Active Directory domains to manage its network, you might need to know which domain a computer belongs to so that you can access other computers and resources on the network.
Open System by clicking the Start button , clicking Control Panel, clicking System and Maintenance, and then clicking System.
If your computer is connected to a domain, under Computer name, domain, and workgroup settings, you will see the name of the domain your computer belongs to. If your computer is connected to a workgroup, you will see the name of the workgroup your computer belongs to.