Yes — theseus.observer has IPv6.

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

IPv6 readiness

Website, mail and DNS all work over IPv6.

Website over IPv6 theseus.observer has 2 IPv6 addresses and answers on every one we tested. ✓ 2606:4700:3037::ac43:8ba7 answers · 443✓ 2606:4700:3036::6815:1af3 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. annabel.ns.cloudflare.com ✓porter.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://theseus.observer/ via 2606:4700:3037::ac43:8ba7 → 302https://icy-sun-916c.cloudflareaccess.com/cdn-cgi/access/login/theseus.observer?kid=a792cece08f4a8a2a6211518a5e91dfb14699f33c28657b2ed607dfd7dd334ce&meta=eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIsImtpZCI6Ijg2OGFmMjMzMzMwYTk2ZmFjNTUzMTBhMmQyN2E2MmQ1ZWM1YWY5Zjg3ZDBhOTg5OTNhMzk0MjZlMDg1NGI2NzcifQ.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.QCjGm01QmibBheV0A8KVw9yp0F0uB7CsG6lFU7zIorclqV-3VlkZ2Lvt7SEhCtMq-wBBhoOt02NxnAsJtQ_AH9If8Xlf7VR6J58Q0DtzWmAwXboxFZGziuEjrzBtJELExxIQjJRtRrMA7aaQgjSzhbzGKu8p1Vuyxhaz2uwaLvCcjeUM5zhqQEYBSPG8i8DvmES8sxOsiWreuoUDDJrG7W-GIQaf3AI8aCTe0p_78bSxmah9VcnFsKs_0KkDxqksoEOYuPoCLp-pJ-kLzguQNLSbxpNRb1gx7rry0kvq93l4jKnTT0L03WttXr0ChrGnyEk_8y3c8ApOfAZl-LdgPA&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/theseus.observer.svg)](https://aaaa.bot/theseus.observer)

Check again

theseus.observer Has IPv6

A (IPv4)	104.21.26.243 172.67.139.167
AAAA (IPv6)	2606:4700:3037::ac43:8ba7 2606:4700:3036::6815:1af3

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: theseus.observer
Measured 2026-11-06 21:42:43 UTC by aaaa.bot (one server on Fly.io, region iad)

A (IPv4):    104.21.26.243, 172.67.139.167
AAAA (IPv6): 2606:4700:3037::ac43:8ba7, 2606:4700:3036::6815:1af3

Readiness grade A: Website, mail and DNS all work over IPv6.
- Website over IPv6: theseus.observer has 2 IPv6 addresses and answers on every one we tested.
    2606:4700:3037::ac43:8ba7: answers (TCP 443)
    2606:4700:3036::6815:1af3: 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://theseus.observer/ via 2606:4700:3037::ac43:8ba7 -> HTTP 302, certificate: valid
    https://icy-sun-916c.cloudflareaccess.com/cdn-cgi/access/login/theseus.observer?kid=a792cece08f4a8a2a6211518a5e91dfb14699f33c28657b2ed607dfd7dd334ce&meta=eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIsImtpZCI6Ijg2OGFmMjMzMzMwYTk2ZmFjNTUzMTBhMmQyN2E2MmQ1ZWM1YWY5Zjg3ZDBhOTg5OTNhMzk0MjZlMDg1NGI2NzcifQ.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.QCjGm01QmibBheV0A8KVw9yp0F0uB7CsG6lFU7zIorclqV-3VlkZ2Lvt7SEhCtMq-wBBhoOt02NxnAsJtQ_AH9If8Xlf7VR6J58Q0DtzWmAwXboxFZGziuEjrzBtJELExxIQjJRtRrMA7aaQgjSzhbzGKu8p1Vuyxhaz2uwaLvCcjeUM5zhqQEYBSPG8i8DvmES8sxOsiWreuoUDDJrG7W-GIQaf3AI8aCTe0p_78bSxmah9VcnFsKs_0KkDxqksoEOYuPoCLp-pJ-kLzguQNLSbxpNRb1gx7rry0kvq93l4jKnTT0L03WttXr0ChrGnyEk_8y3c8ApOfAZl-LdgPA&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/PQEsKkggS3

Permanent link: aaaa.bot/r/PQEsKkggS3 · How we measure

Checked 2026-11-06 21:42:43 UTC. Full DNS report: dns.pizza/domain/theseus.observer · Age, certificate and blocklists: how.is/theseus.observer · JSON: /api/v1/theseus.observer