Yes — 4n5.app has IPv6.

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

IPv6 readiness

Website, mail and DNS all work over IPv6.

Website over IPv6 4n5.app has 2 IPv6 addresses and answers on every one we tested. ✓ 2606:4700:3036::ac43:dd2e answers · 443✓ 2606:4700:3033::6815:237d answers · 443	yes
www over IPv6 www.4n5.app has 2 IPv6 addresses and answers on every one we tested. ✓ 2606:4700:3036::ac43:dd2e answers · 443✓ 2606:4700:3033::6815:237d 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. fatima.ns.cloudflare.com ✓johnny.ns.cloudflare.com ✓	yes

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

https://4n5.app/ via 2606:4700:3036::ac43:dd2e → 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/4n5.app.svg)](https://aaaa.bot/4n5.app)

Check again

4n5.app Has IPv6

A (IPv4)	104.21.35.125 172.67.221.46
AAAA (IPv6)	2606:4700:3036::ac43:dd2e 2606:4700:3033::6815:237d

www.4n5.app Has IPv6

A (IPv4)	104.21.35.125 172.67.221.46
AAAA (IPv6)	2606:4700:3036::ac43:dd2e 2606:4700:3033::6815:237d

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: 4n5.app
Measured 2026-11-05 10:59:55 UTC by aaaa.bot (one server on Fly.io, region iad)

A (IPv4):    104.21.35.125, 172.67.221.46
AAAA (IPv6): 2606:4700:3036::ac43:dd2e, 2606:4700:3033::6815:237d
www AAAA:    2606:4700:3036::ac43:dd2e, 2606:4700:3033::6815:237d

Readiness grade A: Website, mail and DNS all work over IPv6.
- Website over IPv6: 4n5.app has 2 IPv6 addresses and answers on every one we tested.
    2606:4700:3036::ac43:dd2e: answers (TCP 443)
    2606:4700:3033::6815:237d: answers (TCP 443)
- www over IPv6: www.4n5.app has 2 IPv6 addresses and answers on every one we tested.
    2606:4700:3036::ac43:dd2e: answers (TCP 443)
    2606:4700:3033::6815:237d: 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://4n5.app/ via 2606:4700:3036::ac43:dd2e -> HTTP 200, certificate: valid
DNS answers via DNS-over-HTTPS (Cloudflare). Method: https://aaaa.bot/method
Permanent link: https://aaaa.bot/r/UkST7EUc9N

Permanent link: aaaa.bot/r/UkST7EUc9N · How we measure

Checked 2026-11-05 10:59:55 UTC. Full DNS report: dns.pizza/domain/4n5.app · Age, certificate and blocklists: how.is/4n5.app · JSON: /api/v1/4n5.app