When adding new domain, use asterisk (*) as a wildcard to also cover all subdomains. For example *.mysite.com includes both help.mysite.com and test.mysite.com. Defining www.mysite.com will also include all sub-directories such as www.mysite.com/section.
If your website can be accessed with and without the www, make sure you enter both domains (eg. mysite.com and www.mysite.com).
The developement domains are automatically recognized: localhost, 127.0.0.1, 0.0.0:3000.