To create a child domain where the DNS domain name contains the name of the parent domain:
01. Add your the Windows Server 2003 computer that will be the domain controller in the child domain as a member server in the parent domain.
02. On the member server, press Start /run / dcpromo / OK.
03. Press Next on the first page of the Active Directory Installation Wizard.
04. Make sure you understand the list of Windows operating systems that will NOT function in a Windows Server 2003 domain, and press NEXT.
05. Select Domain controller for a new domain and press Next.
06. Select Child domain in an existing domain tree and press Next.
07. On the Network Credentials page, type a user name who is a domain administrator in the parent domain, their password, and parent domain. Press Next.
08. On the Child Domain Installation page, type the parent domain name into the Parent Domain box and the child domain name into the Child Domain box.
09. Press Next.
10. On the NetBIOS Domain Name page, accept the suggested domain NetBIOS name and press Next.
11. On the Database and Log Locations page, accept the default settings and press Next.
12. On the Shared System Volume page, accept the default settings press Next.
13. On the DNS Registration Diagnostics page, check the diagnostic results and press Next.
14. On the Permissions page, select the permission level that you desire and press Next.
15. On the Directory Services Restore Mode Administrator Password page, type a password into the Restore Mode Password and Confirm Password boxes, and press Next.
16. On the Summary page, press Next to complete the Active Directory configuration, which may take several minutes.
17. Press Finish.
18. Press Restart Now.
19. Log on as an administrator.
20. Open Active Directory Domains and Trusts from the Administrative Tools folder.
21. Verify that the subdomain is listed as a child domain under the parent domain (in the console tree).
22. Right-click the child domain object and press Manage to start the Active Directory Users and Computers snap-in for the child domain.
23. Expand the domain tree and select Domain Controllers.
24. In the Details pane, right-click the server object and press Properties, to verify that the DNS name is correct.