[DownGoat]

Would be interesting to snatch one of these domains should the ever be available. If the author has a list of the domains 40k different apps called, there must be some requests going out to domains that are no longer registered.

[ddxv]

That's pretty interesting! I was surprised how many domains like this show up as fairly recent registrations.

[mxuribe]

So, the mischievous part of my brain is activated....what could be done with such domain names? :-)

[DownGoat]

Depends a lot on what they were used for. Maybe they are downloading some HTML to render in a view, images, icons or other assets, or just posting some form of telemetry.