I think you have to have either the subdomain listed in the DNS, OR a "wildcard" DNS entry that can catch it and re-direct it.
I just tried wwwe.nielsentech.com and I get a server not found.
The www.nielsentech.com and just nielsentech.com are susposed to be different things and not the same. However, most servers are set so both will work for all the lazy people that do not want to type in the "www".
nielsentech.com is a domain, not a server.
In www.nielsentech.com the www is the server address.
Just as ftp.nielsentech.com is an ftp server address.
Does that make sense?
So for a request to reach xxx.nielsentech.com there has to be a DNS entry that can do something with that request.
If your DNS could be set to send [anything].nielsentech.com to your site, then it may be possible with programming like PHP to see what the URL is that is being requested and then do a redirection from a scripted home page... But I'm not sure about this...