[keeperofdakeys]

  dig +noall +answer   A ai
  ai.   86006 IN A 209.59.119.34

For better or worse the developers of browsers/libraires decided to allow it, it takes extra code to check for it and block it. Now that sites rely on it they can't exactly back track. Another strange one is domains with names that end in hypen - "example-.example.com". These are technically against standards, and don't work on linux/unix based OSs. However they happily work on windows. I've seen a github username that ended in -, which prevented me from viewing their github.io site. (Github seem to no longer allow this).

[maxh-]

I have one of those, and I learned about this when I created a github.io site. It worked fine on Chrome in Windows, but Firefox read the SSL cert as invalid. It took me a while to figure out that it was the URL that was invalid.

[jfrunyon]

> For better or worse the developers of browsers/libraires decided to allow it, it takes extra code to check for it and block it

It's pretty integral to the functioning of DNS: a hierarchy of names which each have records.

[kuschku]

http://-emmawatson.tumblr.com/ is a real site, accessible only from Windows

[tpush]

Works in Safari on macOS. It's mostly just a solid black page, though.

[Tijdreiziger]

I'm on Windows and it throws an HSTS error for me.