I see thanks.The primary domain is a layer between your Mumara master domain and the tracking domain. You can also set the primary domain the same as your Mumara domain (this is Mumara's default settings). Using CNAME or even htaccess redirection doesn't expose your Mumara domain unless someone finds the CNAME value of the tracking domain. However, in htaccess redirection, your Mumara domain appears within the redirection loop.