Yes — doi.org has IPv6.

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

IPv6 readiness

Works over IPv6, with one gap: its mail servers lack IPv6.

Website over IPv6 doi.org has 3 IPv6 addresses and answers on every one we tested. ✓ 2606:4700:20::681a:584 answers · 443✓ 2606:4700:20::ac43:4503 answers · 443✓ 2606:4700:20::681a:484 answers · 443	yes
www over IPv6 www.doi.org has 3 IPv6 addresses and answers on every one we tested. ✓ 2606:4700:20::681a:484 answers · 443✓ 2606:4700:20::681a:584 answers · 443✓ 2606:4700:20::ac43:4503 answers · 443	yes
Mail servers (MX) have IPv6 None of the mail servers has an AAAA record. mx.zoho.eu ✗mx2.zoho.eu ✗mx3.zoho.eu ✗	no
Nameservers have IPv6 2 of 2 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up. josh.ns.cloudflare.com ✓zita.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://doi.org/ via 2606:4700:20::681a:584 → 301https://www.doi.org/ via 2606:4700:20::681a:484 → 200

works

What's keeping doi.org from an A

Mail servers without IPv6
mx.zoho.eu, mx2.zoho.eu, mx3.zoho.eu have no AAAA record, so mail from IPv6-only servers can't reach them directly. If a provider runs your mail, that's their setting; if you run it, add AAAA records for these hosts.

Check again

doi.org Has IPv6

A (IPv4)	172.67.69.3 104.26.4.132 104.26.5.132
AAAA (IPv6)	2606:4700:20::681a:584 2606:4700:20::ac43:4503 2606:4700:20::681a:484

www.doi.org Has IPv6

A (IPv4)	172.67.69.3 104.26.4.132 104.26.5.132
AAAA (IPv6)	2606:4700:20::681a:484 2606:4700:20::681a:584 2606:4700:20::ac43:4503

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: doi.org
Measured 2026-10-30 18:04:32 UTC by aaaa.bot (one server on Fly.io, region iad)

A (IPv4):    172.67.69.3, 104.26.4.132, 104.26.5.132
AAAA (IPv6): 2606:4700:20::681a:584, 2606:4700:20::ac43:4503, 2606:4700:20::681a:484
www AAAA:    2606:4700:20::681a:484, 2606:4700:20::681a:584, 2606:4700:20::ac43:4503

Readiness grade B: Works over IPv6, with one gap: its mail servers lack IPv6.
- Website over IPv6: doi.org has 3 IPv6 addresses and answers on every one we tested.
    2606:4700:20::681a:584: answers (TCP 443)
    2606:4700:20::ac43:4503: answers (TCP 443)
    2606:4700:20::681a:484: answers (TCP 443)
- www over IPv6: www.doi.org has 3 IPv6 addresses and answers on every one we tested.
    2606:4700:20::681a:484: answers (TCP 443)
    2606:4700:20::681a:584: answers (TCP 443)
    2606:4700:20::ac43:4503: answers (TCP 443)
- Mail servers (MX) have IPv6: None of the mail servers 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://doi.org/ via 2606:4700:20::681a:584 -> HTTP 301, certificate: valid
    https://www.doi.org/ via 2606:4700:20::681a:484 -> HTTP 200, certificate: valid
DNS answers via DNS-over-HTTPS (Cloudflare). Method: https://aaaa.bot/method
Permanent link: https://aaaa.bot/r/usrKt2QLkd

Permanent link: aaaa.bot/r/usrKt2QLkd · How we measure

Checked 2026-10-30 18:04:32 UTC — one of the top 1,000 sites, re-checked weekly. Re-check now. Full DNS report: dns.pizza/domain/doi.org · JSON: /api/v1/doi.org