No — ftp.fio.cz is IPv4 only.

Has an IPv4 address but no IPv6 (AAAA) record. IPv6-only visitors can't reach it directly.

D
IPv6 readiness
The website has no IPv6.
Website over IPv6
ftp.fio.cz has no AAAA record.		no
Mail servers (MX) have IPv6
At least one mail server has no AAAA record (1 of 3 checked do).
www1.fio.cz ✗smtp1.fio.cz ✗smtp2.fio.cz ✓
partly
Nameservers have IPv6
4 of 6 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up.
ns1.fio.cz ✗ns2.fio.cz ✗dns41.cloudns.net ✓dns42.cloudns.net ✓dns43.cloudns.net ✓dns44.cloudns.net ✓
yes

What's keeping ftp.fio.cz from an A

  1. ftp.fio.cz is an alias of www1.fio.cz, which has no IPv6
    ftp.fio.cz is a CNAME, so it can't also have its own AAAA record. Ask whoever runs www1.fio.cz to enable IPv6 there — or replace the alias with the A and AAAA records they give you. Why some hosts don't offer IPv6
  2. Mail servers without IPv6
    www1.fio.cz, smtp1.fio.cz have no AAAA record, so mail from IPv6-only servers can't reach them directly. If a provider runs your mail, that's their setting; if you run it, add AAAA records for these hosts.

Check again

ftp.fio.cz  IPv4 only

Alias ofwww1.fio.cz
A (IPv4)92.38.6.12
AAAA (IPv6)none

What this means

Visitors on IPv6-only networks (many mobile carriers) can still reach it, but only through a translator their carrier runs (NAT64). The site itself has no IPv6 address — and you can't make one up from the IPv4. Why some hosts don't offer it

Copy the evidence — a citation-ready record of this measurement

 Permanent link: aaaa.bot/r/EX3hT_OWyl · How we measure

Checked 2026-11-05 19:03:23 UTC. Full DNS report: dns.pizza/domain/ftp.fio.cz · Age, certificate and blocklists: how.is/ftp.fio.cz · JSON: /api/v1/ftp.fio.cz