THE DIFFERENCE BETWEEN DOMAIN CONTROLLERS AND SERVERS OR WORKSTATIONS
As has been stated previously, domain controllers use the domains accounts database which is stored on the PDC and replicated [copied] to each BDC in the domain. This means it is not possible to logon locally to a Domain Controller, but rather, users logon to the Domain.

Servers and workstations have their own local accounts database. This means it is possible for an administrator on the workstation to create a local workstation account, which is not the same as the domain account, and allow users to logon to the local computer rather than the domain.

Currently, you should have the PDC and a Windows NT workstation running. You are logged onto the domain at the PDC as administrator, and as yet, have not logged onto the NT Workstation computer.

Perform the following task at the NT Workstation Computer

1. Press CTRL+ALT+DEL to begin the logon process and display the logon dialog box
2. Click the down arrow associated with the entry From [this specifies the domain or computer from which the user is logging on from]
3. Fill in the list below, specifying the options given in the From List

   	...................................................................................
   
   	...................................................................................
   

4. Logon to the workstation, then shutdown the computer and restart it as a BDC

   Start->Shutdown->Restart the Computer

5. This time, list the options given in the From List for the BDC

   	...................................................................................
   
   	...................................................................................
   

Summary
Domain controllers do not allow users to logon locally to the computer. Users actually logon to the domain. Workstations and servers have their own accounts database, thus users can be granted permission to logon locally, as well as the domain.