In the site settings, make sure that vitualsite.com is set as a web alias for the site
www.virtualsite.com and then in the dns make sure there is an A Record pointing virtualsite.com to the same ip as
www.virtualsite.com. That is assuming that you are running your own dns. If not then this will have to be taken care of in the Rackshack dns and somebody else will have to explain that as I don't use it.