This guide is recommended for businesses who only want to add a single client to a domain. If you want to add multiple clients at the same time to a domain there is a faster way, which will be covered in a future how-to blog.
1. Login to the client machine you want to add to the domain
2. Select Start, right-click Computer and select Properties
3. The System window box appears. Access the Change settings link under the Computer name, domain and workgroup settings.
4. The System Properties dialog box opens in the Computer Name tab. Since you want to add this client to your domain, click Change in order ‘to rename this computer or change its domain or workgroup’.
In the Computer Name/Domain Changes dialog box, select the Domain radio button and fill in your Domain name you want the client to join. Click OK to continue.
A Windows Security dialog box appears. Type the name and password of an account with permission to join the domain (i.e. administrator) and click OK. A message box will display welcoming you to your specified domain. Click OK twice to restart your computer to apply these changes.
The client is now joined to the domain!