Introducing Microsoft Windows Longhorn Server

We type net stop dens; we can now stop the DNS Server service without getting an error because the service is now present on the machine. Now that our machine is a DNS Server, we can use the dnscmd.exe command to further configure this role if we want from the command line.

Installing other server roles is similar to what we just did and uses the ocsetup.exe command,
With the exception being that the process installs the Active Directory role. This is because Dcpromo.exe in Windows Server 2008 now installs the Active Directory binaries during pro- motion and uninstalls the binaries during demotion, so you should not use ocsetup.exe to add   or remove the Active Directory role as then the promotion/demotion will not take place and your server may not function correctly.