In your first config, it seems that you have shared the users and that you have manage your master website from "
www.master.com"
Therefore the "www" is mandatory. If you had manage the master from "master.com" (without the "www" you would be able to have the www and without the www for the master.
The cookies generated would have been ".master.com" and not "master.com" (becarefull the dot in front of the url). In the current case, you can see ".
www.master.com" that accept fake.
www.domain.com or whatever in front of the "www" (because there is a dot).
In the second config, you have not shared anything.
So there is no "cookies" infos computed.