Yes — mrcat.science has IPv6.

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

IPv6 readiness

Website, mail and DNS all work over IPv6.

Website over IPv6 mrcat.science has 2 IPv6 addresses and answers on every one we tested. ✓ 2606:4700:3037::ac43:a922 answers · 443✓ 2606:4700:3035::6815:1b6f 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. elisa.ns.cloudflare.com ✓kellen.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://mrcat.science/ via 2606:4700:3037::ac43:a922 → 302https://mrcat-nference.cloudflareaccess.com/cdn-cgi/access/login/mrcat.science?kid=7bb2634302e3da3b9e253c00fc48856b2e6f979fa6b8b2bc6304c490c374ccc7&meta=eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIsImtpZCI6Ijg2OGFmMjMzMzMwYTk2ZmFjNTUzMTBhMmQyN2E2MmQ1ZWM1YWY5Zjg3ZDBhOTg5OTNhMzk0MjZlMDg1NGI2NzcifQ.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.nEWij8uRs8zlQ91GU8BxY73aAWWKgMb7xGJulDNouQWzgdkSXXQpmqIysjyni05DgjmYJUMphg2SqnutoausmbZR0Ay89OD_3Bsowc4kICZHsgxsO5ldQX9Bb-NgYFng5V7BivHcZc9JoLlJZHJ5bK4LJsz136hSl2arTYtmGwirPfRQ6Slw16l-HLPvHxLXG6At1syY41rNFXkiGQLWKccWcf5_w1uQh5EWiWut3sdFGgJWbXRHV3K9zqelThkPHGUZUM_QQaRVA_3rFMCT5s9xQM_Rp_vuCgP-pyHgTsZwuv2DYrQfllR8hb8Pf9lj_TsTkAQqcl5W577dKR8I5A&redirect_url=%2F via 2606:4700:300a::6813:c31d → 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/mrcat.science.svg)](https://aaaa.bot/mrcat.science)

Check again

mrcat.science Has IPv6

A (IPv4)	172.67.169.34 104.21.27.111
AAAA (IPv6)	2606:4700:3037::ac43:a922 2606:4700:3035::6815:1b6f

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: mrcat.science
Measured 2026-11-05 05:36:27 UTC by aaaa.bot (one server on Fly.io, region iad)

A (IPv4):    172.67.169.34, 104.21.27.111
AAAA (IPv6): 2606:4700:3037::ac43:a922, 2606:4700:3035::6815:1b6f

Readiness grade A: Website, mail and DNS all work over IPv6.
- Website over IPv6: mrcat.science has 2 IPv6 addresses and answers on every one we tested.
    2606:4700:3037::ac43:a922: answers (TCP 443)
    2606:4700:3035::6815:1b6f: 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://mrcat.science/ via 2606:4700:3037::ac43:a922 -> HTTP 302, certificate: valid
    https://mrcat-nference.cloudflareaccess.com/cdn-cgi/access/login/mrcat.science?kid=7bb2634302e3da3b9e253c00fc48856b2e6f979fa6b8b2bc6304c490c374ccc7&meta=eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIsImtpZCI6Ijg2OGFmMjMzMzMwYTk2ZmFjNTUzMTBhMmQyN2E2MmQ1ZWM1YWY5Zjg3ZDBhOTg5OTNhMzk0MjZlMDg1NGI2NzcifQ.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.nEWij8uRs8zlQ91GU8BxY73aAWWKgMb7xGJulDNouQWzgdkSXXQpmqIysjyni05DgjmYJUMphg2SqnutoausmbZR0Ay89OD_3Bsowc4kICZHsgxsO5ldQX9Bb-NgYFng5V7BivHcZc9JoLlJZHJ5bK4LJsz136hSl2arTYtmGwirPfRQ6Slw16l-HLPvHxLXG6At1syY41rNFXkiGQLWKccWcf5_w1uQh5EWiWut3sdFGgJWbXRHV3K9zqelThkPHGUZUM_QQaRVA_3rFMCT5s9xQM_Rp_vuCgP-pyHgTsZwuv2DYrQfllR8hb8Pf9lj_TsTkAQqcl5W577dKR8I5A&redirect_url=%2F via 2606:4700:300a::6813:c31d -> HTTP 200, certificate: valid
DNS answers via DNS-over-HTTPS (Cloudflare). Method: https://aaaa.bot/method
Permanent link: https://aaaa.bot/r/dP9ZuOFA-n

Permanent link: aaaa.bot/r/dP9ZuOFA-n · How we measure

Checked 2026-11-05 05:36:27 UTC. Full DNS report: dns.pizza/domain/mrcat.science · Age, certificate and blocklists: how.is/mrcat.science · JSON: /api/v1/mrcat.science