http://ai/
This is a real, working URL, even if HN doesn't recognize it.
http://ai/
http://ai/
Edit: I've tried a few country codes, and http://ca/ goes to ca.com, and http://de/ goes to de.com, but http://se/ goes to https://www.schneider-electric.com/ww/en/ so it's not that country codes default to the registrar. Weird...
http://ae/ goes to https://www.ae.com/ American Eagle
http://mx/ goes to https://data.mx.com/ MX Technologies Inc.
The list of two-letter country codes can be found here: https://en.m.wikipedia.org/wiki/ISO_3166-1_alpha-2
Edit: I'm thinking this is an artifact of my web browser, as these work for me with Firefox but not Chromium.
OP, which web browser are you using?
Edit 2: The original one, http://ai/ does indeed work for me in Chromium as well.