Yes — seznam.cz has IPv6.

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

IPv6 readiness

Website, mail and DNS all work over IPv6.

Website over IPv6 seznam.cz has 2 IPv6 addresses and answers on every one we tested. ✓ 2a02:598:2::1222 answers · 443✓ 2a02:598:a::79:222 answers · 443	yes
www over IPv6 www.seznam.cz has 2 IPv6 addresses and answers on every one we tested. ✓ 2a02:598:2::1222 answers · 443✓ 2a02:598:a::79:222 answers · 443	yes
Mail servers (MX) have IPv6 Every mail server has an AAAA record. mx1.seznam.cz ✓mx2.seznam.cz ✓	yes
Nameservers have IPv6 2 of 2 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up. ams.seznam.cz ✓ans.seznam.cz ✓	yes

HTTPS over IPv6 · not part of the grade yet
Loads over IPv6 with a valid certificate after 1 redirect: HTTP 200.

https://seznam.cz/ via 2a02:598:2::1222 → 301https://www.seznam.cz/ via 2a02:598:2::1222 → 200

works

Nothing keeping you from an A

Nothing to fix
Show it off: add the badge to your README.
[![IPv6](https://aaaa.bot/badge/seznam.cz.svg)](https://aaaa.bot/seznam.cz)

Check again

seznam.cz Has IPv6

A (IPv4)	77.75.79.222 77.75.77.222
AAAA (IPv6)	2a02:598:2::1222 2a02:598:a::79:222

www.seznam.cz Has IPv6

A (IPv4)	77.75.77.222 77.75.79.222
AAAA (IPv6)	2a02:598:2::1222 2a02:598:a::79:222

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: seznam.cz
Measured 2026-10-31 05:04:31 UTC by aaaa.bot (one server on Fly.io, region iad)

A (IPv4):    77.75.79.222, 77.75.77.222
AAAA (IPv6): 2a02:598:2::1222, 2a02:598:a::79:222
www AAAA:    2a02:598:2::1222, 2a02:598:a::79:222

Readiness grade A: Website, mail and DNS all work over IPv6.
- Website over IPv6: seznam.cz has 2 IPv6 addresses and answers on every one we tested.
    2a02:598:2::1222: answers (TCP 443)
    2a02:598:a::79:222: answers (TCP 443)
- www over IPv6: www.seznam.cz has 2 IPv6 addresses and answers on every one we tested.
    2a02:598:2::1222: answers (TCP 443)
    2a02:598:a::79:222: answers (TCP 443)
- Mail servers (MX) have IPv6: Every mail server 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 after 1 redirect: HTTP 200.
    https://seznam.cz/ via 2a02:598:2::1222 -> HTTP 301, certificate: valid
    https://www.seznam.cz/ via 2a02:598:2::1222 -> HTTP 200, certificate: valid
DNS answers via DNS-over-HTTPS (Cloudflare). Method: https://aaaa.bot/method
Permanent link: https://aaaa.bot/r/yE3zNZFkdq

Permanent link: aaaa.bot/r/yE3zNZFkdq · How we measure

Checked 2026-10-31 05:04:31 UTC — one of the top 1,000 sites, re-checked weekly. Re-check now. Full DNS report: dns.pizza/domain/seznam.cz · JSON: /api/v1/seznam.cz