Yes — irozhlas.cz has IPv6.

Has both IPv4 (A) and IPv6 (AAAA) addresses.

Measured 2026-11-04 13:03 UTC. We reuse a result for up to a week, so we aren't testing the same site over and over. Check irozhlas.cz now

IPv6 readiness

Works over IPv6, with one gap: its mail servers lack IPv6.

Website over IPv6 irozhlas.cz has 3 IPv6 addresses and answers on every one we tested. ✓ 2606:4700:20::ac43:4a9d answers · 443✓ 2606:4700:20::681a:e3c answers · 443✓ 2606:4700:20::681a:f3c answers · 443	yes
www over IPv6 www.irozhlas.cz has 3 IPv6 addresses and answers on every one we tested. ✓ 2606:4700:20::681a:e3c answers · 443✓ 2606:4700:20::681a:f3c answers · 443✓ 2606:4700:20::ac43:4a9d answers · 443	yes
Mail servers (MX) have IPv6 None of the mail servers has an AAAA record. ddei1.cro.cz ✗ddei2.cro.cz ✗	no
Nameservers have IPv6 2 of 2 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up. davina.ns.cloudflare.com ✓sergi.ns.cloudflare.com ✓	yes

First measured 2026-11-04; last confirmed 2026-11-04.

HTTPS over IPv6 · not part of the grade yet
Loads over IPv6 with a valid certificate: HTTP 403.

https://irozhlas.cz/ via 2606:4700:20::ac43:4a9d → 403

works

What's keeping irozhlas.cz from an A

Mail servers without IPv6
ddei1.cro.cz, ddei2.cro.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

irozhlas.cz Has IPv6

A (IPv4)	104.26.15.60 104.26.14.60 172.67.74.157
AAAA (IPv6)	2606:4700:20::ac43:4a9d 2606:4700:20::681a:e3c 2606:4700:20::681a:f3c

www.irozhlas.cz Has IPv6

A (IPv4)	104.26.15.60 104.26.14.60 172.67.74.157
AAAA (IPv6)	2606:4700:20::681a:e3c 2606:4700:20::681a:f3c 2606:4700:20::ac43:4a9d

Browsers on dual-stack networks will usually pick IPv6 here (the "Happy Eyeballs" algorithm races both and prefers v6).

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

IPv6 measurement: irozhlas.cz
Measured 2026-11-04 13:03:07 UTC by aaaa.bot (one server on Fly.io, region iad)

A (IPv4):    104.26.15.60, 104.26.14.60, 172.67.74.157
AAAA (IPv6): 2606:4700:20::ac43:4a9d, 2606:4700:20::681a:e3c, 2606:4700:20::681a:f3c
www AAAA:    2606:4700:20::681a:e3c, 2606:4700:20::681a:f3c, 2606:4700:20::ac43:4a9d

Readiness grade B: Works over IPv6, with one gap: its mail servers lack IPv6.
- Website over IPv6: irozhlas.cz has 3 IPv6 addresses and answers on every one we tested.
    2606:4700:20::ac43:4a9d: answers (TCP 443)
    2606:4700:20::681a:e3c: answers (TCP 443)
    2606:4700:20::681a:f3c: answers (TCP 443)
- www over IPv6: www.irozhlas.cz has 3 IPv6 addresses and answers on every one we tested.
    2606:4700:20::681a:e3c: answers (TCP 443)
    2606:4700:20::681a:f3c: answers (TCP 443)
    2606:4700:20::ac43:4a9d: answers (TCP 443)
- Mail servers (MX) have IPv6: None of the mail servers has an AAAA record.
- Nameservers have IPv6: 2 of 2 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up.

Reachability = a TCP connection opened on port 443 (or 80).

HTTPS over IPv6 (not graded): Loads over IPv6 with a valid certificate: HTTP 403.
    https://irozhlas.cz/ via 2606:4700:20::ac43:4a9d -> HTTP 403, certificate: valid
DNS answers via DNS-over-HTTPS (Cloudflare). Method: https://aaaa.bot/method
Permanent link: https://aaaa.bot/r/jwYeGwUrz-

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

Checked 2026-11-04 13:03:07 UTC. Full DNS report: dns.pizza/domain/irozhlas.cz · Age, certificate and blocklists: how.is/irozhlas.cz · JSON: /api/v1/irozhlas.cz