Yes — red.cymru has IPv6.

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

IPv6 readiness

Website, mail and DNS all work over IPv6.

Website over IPv6 red.cymru has 2 IPv6 addresses and answers on every one we tested. ✓ 2606:4700:3037::6815:394e answers · 443✓ 2606:4700:3035::ac43:bdb0 answers · 443	yes
Mail servers (MX) have IPv6 No MX records, so mail goes to the domain's own address (implicit MX). It has an AAAA record.	yes
Nameservers have IPv6 2 of 2 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up. april.ns.cloudflare.com ✓micah.ns.cloudflare.com ✓	yes

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

https://red.cymru/ via 2606:4700:3037::6815:394e → 302https://orange-lab-938c.cloudflareaccess.com/cdn-cgi/access/login/red.cymru?kid=ece3499e4951f68169fb990484cbb21b193a86d74c44dba20148d964e8087795&meta=eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIsImtpZCI6ImYwYTRjZDAyZGM2MGMxNjA0Y2I0NjFiYzI3OTI5OWFmZTk3NGFiZmZlZTk2ZjhkMjg0Y2ZhNzQ5ZDgzN2UyYTcifQ.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.gsM-LJ2KjzAHAtDzBvGbV6mzxxRZcTWzCvK1ufHHKPJbcDNHuQjScaglKSuqoU8r1k_3jrmOoCHAlFp6QH_fwvdJcE6xyreQlyniQOa4MkyY7iOQoX3_JWibqqe-8iMkT4G4C8OmHskkdmeojdPYNRTybB3ShAxFu23DHG8UEf9B6USjfeGeAwQSwNurtWqT2zxEM09KwK9_ruUvNNq9VnlzynyKc2Gk8gfXqDlct11bhgWyqLk4Byzu58DVmLjLTSUKK6ixBYX-JgI5uSOHiV_ec_lSo89-F8Bnn3acMSE1JqtAdaxIw32gfaT0B2brjGHJHAz_bvuvxjyBu8902g&redirect_url=%2F via 2606:4700:300a::6813:c21d → 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/red.cymru.svg)](https://aaaa.bot/red.cymru)

Check again

red.cymru Has IPv6

A (IPv4)	104.21.57.78 172.67.189.176
AAAA (IPv6)	2606:4700:3037::6815:394e 2606:4700:3035::ac43:bdb0

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: red.cymru
Measured 2026-11-07 23:55:28 UTC by aaaa.bot (one server on Fly.io, region iad)

A (IPv4):    104.21.57.78, 172.67.189.176
AAAA (IPv6): 2606:4700:3037::6815:394e, 2606:4700:3035::ac43:bdb0

Readiness grade A: Website, mail and DNS all work over IPv6.
- Website over IPv6: red.cymru has 2 IPv6 addresses and answers on every one we tested.
    2606:4700:3037::6815:394e: answers (TCP 443)
    2606:4700:3035::ac43:bdb0: answers (TCP 443)
- Mail servers (MX) have IPv6: No MX records, so mail goes to the domain's own address (implicit MX). It 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://red.cymru/ via 2606:4700:3037::6815:394e -> HTTP 302, certificate: valid
    https://orange-lab-938c.cloudflareaccess.com/cdn-cgi/access/login/red.cymru?kid=ece3499e4951f68169fb990484cbb21b193a86d74c44dba20148d964e8087795&meta=eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIsImtpZCI6ImYwYTRjZDAyZGM2MGMxNjA0Y2I0NjFiYzI3OTI5OWFmZTk3NGFiZmZlZTk2ZjhkMjg0Y2ZhNzQ5ZDgzN2UyYTcifQ.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.gsM-LJ2KjzAHAtDzBvGbV6mzxxRZcTWzCvK1ufHHKPJbcDNHuQjScaglKSuqoU8r1k_3jrmOoCHAlFp6QH_fwvdJcE6xyreQlyniQOa4MkyY7iOQoX3_JWibqqe-8iMkT4G4C8OmHskkdmeojdPYNRTybB3ShAxFu23DHG8UEf9B6USjfeGeAwQSwNurtWqT2zxEM09KwK9_ruUvNNq9VnlzynyKc2Gk8gfXqDlct11bhgWyqLk4Byzu58DVmLjLTSUKK6ixBYX-JgI5uSOHiV_ec_lSo89-F8Bnn3acMSE1JqtAdaxIw32gfaT0B2brjGHJHAz_bvuvxjyBu8902g&redirect_url=%2F via 2606:4700:300a::6813:c21d -> HTTP 200, certificate: valid
DNS answers via DNS-over-HTTPS (Cloudflare). Method: https://aaaa.bot/method
Permanent link: https://aaaa.bot/r/GlDkXIz1EZ

Permanent link: aaaa.bot/r/GlDkXIz1EZ · How we measure

Checked 2026-11-07 23:55:28 UTC. Full DNS report: dns.pizza/domain/red.cymru · Age, certificate and blocklists: how.is/red.cymru · JSON: /api/v1/red.cymru