To improve security in your Active Directory domain, you should rename the administrator account because this lowers the risk of brute force attacks. Renaming the administrator account and resetting its password on all computers in your AD domain can be easily done via Group Policy.
Open the Active Directory Group Policy Management console, create a new GPO, and link it to your desired OU. Of course, you can also work with an existing GPO.
Linking a GPO to an OU
Right-click the new GPO or an existing GPO and select Edit. This will launch the Group Policy editor. Now, browse to the following Group Policy setting: Computer Configuration > Preferences > Control Panel Settings > Local Users and Groups.
Renaming the administrator account
As you can see in the screenshot above, right-click Local Users and Groups and then navigate toNew > Local User.
On the next screen, you select the user name you would like to use for the administrator account:
Selecting the user name
Select the following:
Action – Select Update.
User name – Select Administrator (built-in).
Rename to – Enter the new user name.
Full name – Enter your desired name.
Description – Add a description (optional).
Password – Set a new password (optional).
Check boxes – Verify that the check boxes comply with your company policies.
The GPO is now configured and can be deployed in your network. The refresh interval for computer settings is 90 minutes. If you want to apply the GPO immediately on a client computer, open a command prompt and type gpupdate /force at the command line.
Alternatively, you can reboot the computer. If you are finding that a computer isn’t applying the policy, simply run gpresult /r at a command line to see whether your new GPO is listed:
Checking if the GPO has been applied
If it’s not listed or if you see a permission error message, go back to Active Directory Users and Computers and check the OU to which you have the policy applied. Also check whether the computer contains that OU. Perhaps the computer is in a different OU and therefore doesn’t pick up the policy.
Also check the GPO settings. In the Security Filtering section, ensure that the GPO is applied to Authenticated Users; in the Links section, verify that the correct OU is linked to the GPO :
GPO security filtering
If the policy is still not applied to some of your computers and you have checked all the above, then your domain controllers might not replicate the GPO properly.