@Jacob9 - as of now it will work without a custom URL, since the third party cookie is passed between your site and your SN instance. Moving forward (Utah release timeframe), authentication will not work without custom URL. You'll need to specify and map a custom URL, otherwise you'll only be able to use VA on an external site as 'guest'. 

 

@deepali123 - not that I know of, I used a Wordpress site on a GoDaddy domain.