The wierd lowercase NETBIOS name

I got a call from an associate on how to change a domains NetBIOS name from lower to upper case. At first I was stumped, Was I the one that was out of date. In my head an NetBIOS name is always in uppercase, the same as a FQDN is always in lowercase. Don’t get me started on the special case with Single Label Domains (SLD). First I turned to my colleague Jimmy Andersson to ask if I had missed that day in AD training on why one would do that, he could not really give me any good reason or how. So I turned back to associate that reported it from the beginning. It was a regular Windows 2012R2 installation that had done this. So I tried with a Windows 2012R2 Update installation. And low and behold.. I managed to get the NetBIOS name in lowercase.

A small powershell script to verify NetBIOS name:

Windows 2012R2 lowercase NetBIOS proof

How to do it:

The problem is that its easy to do this error. If you don’t remember to hold shift while typing the NetBIOS name you will get a lowercase NetBIOS name.

Windows 2008R2:

Windows 2008r2 DCPromo NETBIOS selection
In Windows 2008R2 the user cannot write the NetBIOS name in lowercase.

Windows 2012/2012R2:

Windows 2012 Server Manager NETBIOS selection

Windows 10 Technical Preview 2:

Windows 10 Technical Preview 2 Server Manager NETBIOS selection

So after Windows 2008R2 be more careful when creating domains, Not all safe guards that were available in dcpromo has been ported to the server manager.


  1. Calvin Burkhead says

    Is there a way to convert the NetBIOS to uppercase? We accidentally setup our domain lowercase a couple years ago and it causes some odd problems with non-microsoft operating systems.

    • virot says

      I would recommend contacting PSS (Product Support Services). There is a technical option of renaming the domain, but then again that gives other problems. All depends on the size of the domain.

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