Yes — closedtesting.app has IPv6.

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

IPv6 readiness

Website, mail and DNS all work over IPv6.

Website over IPv6 closedtesting.app has 2 IPv6 addresses and answers on every one we tested. ✓ 2a02:4780:84:d3e0:6585:313d:7d20:4af2 answers · 443✓ 2a02:4780:84:c04d:30a7:ebf:c17f:3f80 answers · 443	yes
www over IPv6 www.closedtesting.app has 2 IPv6 addresses and answers on every one we tested. ✓ 2a02:4780:84:a63c:33db:5f52:4974:d298 answers · 443✓ 2a02:4780:84:22f9:1273:93cb:89ea:6820 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. athena.dns-parking.com ✓apollo.dns-parking.com ✓	yes

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

https://closedtesting.app/ via 2a02:4780:84:d3e0:6585:313d:7d20:4af2 → 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/closedtesting.app.svg)](https://aaaa.bot/closedtesting.app)

Check again

closedtesting.app Has IPv6

A (IPv4)	88.222.222.232 2.57.91.166
AAAA (IPv6)	2a02:4780:84:d3e0:6585:313d:7d20:4af2 2a02:4780:84:c04d:30a7:ebf:c17f:3f80

www.closedtesting.app Has IPv6

Alias of	www.closedtesting.app.cdn.hstgr.net
A (IPv4)	191.96.144.118 195.35.60.79
AAAA (IPv6)	2a02:4780:84:a63c:33db:5f52:4974:d298 2a02:4780:84:22f9:1273:93cb:89ea:6820

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: closedtesting.app
Measured 2026-11-03 23:52:14 UTC by aaaa.bot (one server on Fly.io, region iad)

A (IPv4):    88.222.222.232, 2.57.91.166
AAAA (IPv6): 2a02:4780:84:d3e0:6585:313d:7d20:4af2, 2a02:4780:84:c04d:30a7:ebf:c17f:3f80
www AAAA:    2a02:4780:84:a63c:33db:5f52:4974:d298, 2a02:4780:84:22f9:1273:93cb:89ea:6820

Readiness grade A: Website, mail and DNS all work over IPv6.
- Website over IPv6: closedtesting.app has 2 IPv6 addresses and answers on every one we tested.
    2a02:4780:84:d3e0:6585:313d:7d20:4af2: answers (TCP 443)
    2a02:4780:84:c04d:30a7:ebf:c17f:3f80: answers (TCP 443)
- www over IPv6: www.closedtesting.app has 2 IPv6 addresses and answers on every one we tested.
    2a02:4780:84:a63c:33db:5f52:4974:d298: answers (TCP 443)
    2a02:4780:84:22f9:1273:93cb:89ea:6820: 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: HTTP 200.
    https://closedtesting.app/ via 2a02:4780:84:d3e0:6585:313d:7d20:4af2 -> HTTP 200, certificate: valid
DNS answers via DNS-over-HTTPS (Cloudflare). Method: https://aaaa.bot/method
Permanent link: https://aaaa.bot/r/uJDbOZW2dM

Permanent link: aaaa.bot/r/uJDbOZW2dM · How we measure

Checked 2026-11-03 23:52:14 UTC. Full DNS report: dns.pizza/domain/closedtesting.app · Age, certificate and blocklists: how.is/closedtesting.app · JSON: /api/v1/closedtesting.app