eu.org is a public suffix (check the list), which means that every domain below it is treated as it's own seperate security context. Meaning cookies are not shared between domain-a.eu.org and domain-b.eu.org.

If they weren't on the public suffix list, cookies would be shared.

This also affect a myriad of other contexts that the browser applies against the public suffix list.

I didn't think of that. Thanks.

Technically "com." or even just "." could include a A record with a website. However browsers tend to strip the last "." and treat empty or names without "." in them as search terms.

There exist people who disapprove of this behavior.

I understand. I don't like that behavior much myself.

Unlike "com", Anguilla's TLD, "ai", has an A record pointing to a usable HTTP server:

http://ai/

A few years ago I tried all two-letter ([a-z]) TLDs and found some others that were able to handle HTTP requests, but they were either just redirecting to another domain name (the ones I noted down back then don't seem to work anymore) or returning 500 errors (http://uz/).

These examples should at least demonstrate that there shouldn't technically be some special case for resolving TLDs. They work in normal web browsers, and presumably a lack of A records for other TLDs would just be some sort of convention.

I've recently (2022-03) done the same but also .space and all others from https://en.wikipedia.org/wiki/List_of_Internet_top-level_dom... and discovered:

curl http://ai

Apache's Hello world:

curl http://pn

ping tk

ping uz

ping cm

All others had this error:

curl: (6) Could not resolve host: %tld%

You need the trailing dot for it to reliably work: http://ai./