When Active Directory Services are installed on a Windows server 2008 computer to promote it as a domain controller every domain user account has its own User Principal Name followed by a unique UPN Suffix. When there is just one domain in the forest the default UPN suffix offered by the domain is absolutely fine and administrators need not to modify the settings. However in multi domain environment where one domain has several child or grandchild domains default UPN suffix of any domain user account can be very lengthy. When this is the case administrators may want to specify an alternative comparatively shorter UPN suffix for the user accounts in order to make the manageability easier. As an administrator of any Active Directory network infrastructure if you want to specify an additional UPN suffix you are required to follow the steps given as below:
1.Â Â Â Â Â Â Logon to Windows server 2008 the domain controller with Administrator account.
2.Â Â Â Â Â Â Click on Start button and go to Administrative Tools.
3.Â Â Â Â Â Â From the appeared menu go to Active Directory Domains and Trusts and from the opened snap-in right click on Active Directory Domains and Trusts to get the menu.
4.Â Â Â Â Â Â Click on Properties.
5.Â Â Â Â Â Â On the opened box specify an alternate UPN suffix in the available Alternative UPN suffixes text box.
6.Â Â Â Â Â Â Click on Add button and finally click on Ok button to save the changes.