No — t-online.de 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
t-online.de has no AAAA record.		no
www over IPv6
www.t-online.de has 4 IPv6 addresses and answers on every one we tested (4 more not tested).
✓ 2600:9000:215a:3c00:f:f903:2f40:93a1 answers · 443✓ 2600:9000:215a:1c00:f:f903:2f40:93a1 answers · 443✓ 2600:9000:215a:3e00:f:f903:2f40:93a1 answers · 443✓ 2600:9000:215a:d200:f:f903:2f40:93a1 answers · 443– 2600:9000:215a:2200:f:f903:2f40:93a1 not tested– 2600:9000:215a:4800:f:f903:2f40:93a1 not tested– 2600:9000:215a:a00:f:f903:2f40:93a1 not tested– 2600:9000:215a:5400:f:f903:2f40:93a1 not tested
yes
Mail servers (MX) have IPv6
None of the mail servers has an AAAA record.
mx03.t-online.de ✗mx02.t-online.de ✗mx01.t-online.de ✗mx00.t-online.de ✗
no
Nameservers have IPv6
5 of 5 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up.
dns20.dns.t-ipnet.de ✓dns50.dns.t-ipnet.de ✓dns00.dns.t-ipnet.de ✓dns02.dns.t-ipnet.de ✓pns.dtag.de ✓
yes

What's keeping t-online.de from an A

  1. Give t-online.de an IPv6 address
    Ask your hosting provider for the site's IPv6 address (or the hostname to point at), then publish it as an AAAA record. If your host doesn't offer IPv6, a proxy that does can sit in front. How to add an AAAA record
  2. Mail servers without IPv6
    mx03.t-online.de, mx02.t-online.de, mx01.t-online.de, mx00.t-online.de 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

t-online.de  IPv4 only

A (IPv4)34.246.241.220
52.209.116.123
54.217.253.146
AAAA (IPv6)none

www.t-online.de  Has IPv6

A (IPv4)52.85.193.84
52.85.193.68
52.85.193.57
52.85.193.116
AAAA (IPv6)2600:9000:215a:3c00:f:f903:2f40:93a1
2600:9000:215a:1c00:f:f903:2f40:93a1
2600:9000:215a:3e00:f:f903:2f40:93a1
2600:9000:215a:d200:f:f903:2f40:93a1
2600:9000:215a:2200:f:f903:2f40:93a1
2600:9000:215a:4800:f:f903:2f40:93a1
2600:9000:215a:a00:f:f903:2f40:93a1
2600:9000:215a:5400:f:f903:2f40:93a1

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/NIW9uqLJrG · How we measure

Checked 2026-10-30 19:48:43 UTC. Full DNS report: dns.pizza/domain/t-online.de · JSON: /api/v1/t-online.de