I found that browsing http://ai. returns a web page.

This is no longer a public website. If you have come here you are at the wrong place. You probably want to go to one of these sites:

whois.nic.ai To do "whois" lookups.
auction.whois.ai Auction site for expired .ai domains.
whois.ai/faq.html General FAQ for .ai domains.
whois.ai/eppfaq.html FAQ for .ai registrars.
zenaida.cate.ai if you used to login here years ago

This looks like a .ai domain, but it is not xxx.ai., nor is it .ai., but simply ai., and it seems an invalid URL.

How is this URL parsed and DNS resolved? And is this satisfy the specification? (Maybe RFC?)

For example, I looked for the same example with other domain names, but they did not work (com., net.).

  • The URL has a protocol component and a path component. Why do you think it's invalid? Nov 18, 2023 at 17:12
  • DNS is resolved exactly as usual. See dig any ai. or dig any uk. or even dig any com. I don't see the problem here Nov 18, 2023 at 17:13
  • 2
    The fact that it's not common to use naked TLD's doesn't make them invalid.
    – vidarlo
    Nov 18, 2023 at 18:06
  • @ChrisDavies In the RFC 952, hostname is defined as <official hostname> ::= <hname>, <hname> ::= <name>*["."<name>], <name> ::= <let>[*[<let-or-digit-or-hyphen>]<let-or-digit>] . My understanding is that this definition states that hostname necessary consist of one or more letter. And ai. doesn't have hostname, so I consider ai. is invalid.
    – desertpureolive
    Nov 18, 2023 at 18:36
  • 2
    RFC 952 is the obsolete DOD "hosts" file. You should be reading RFCs 1034 and 1035 for DNS, where it's quite clear that ai. is a valid name Nov 18, 2023 at 21:09

1 Answer 1


Just using a dns record

    .           84489   IN  NS  a.root-servers.net.
.           84489   IN  NS  b.root-servers.net.
.           84489   IN  NS  c.root-servers.net.
.           84489   IN  NS  d.root-servers.net.
.           84489   IN  NS  e.root-servers.net.
.           84489   IN  NS  f.root-servers.net.
.           84489   IN  NS  g.root-servers.net.
.           84489   IN  NS  h.root-servers.net.
.           84489   IN  NS  i.root-servers.net.
.           84489   IN  NS  j.root-servers.net.
.           84489   IN  NS  k.root-servers.net.
.           84489   IN  NS  l.root-servers.net.
.           84489   IN  NS  m.root-servers.net.
;; Received 228 bytes from in 71 ms

ai.         172800  IN  NS  a.lactld.org.
ai.         172800  IN  NS  pch.whois.ai.
ai.         172800  IN  NS  anycastdns1-cz.nic.ai.
ai.         172800  IN  NS  anycastdns2-cz.nic.ai.
;; Received 280 bytes from in 248 ms

ai.         3600    IN  A
ai.         3600    IN  NS  a.lactld.org.
ai.         3600    IN  NS  pch.whois.ai.
ai.         3600    IN  NS  anycastdns1-cz.nic.ai.
ai.         3600    IN  NS  anycastdns2-cz.nic.ai.
;; Received 252 bytes from in 133 ms

dig +noadditional +noquestion +nocomments +nocmd +nostats +trace ai. @

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