Yes — ntp.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 ntp.org has an AAAA record and answers on it. ✓ 2001:1838:2000:41b::80:0 answers · 443	yes
www over IPv6 www.ntp.org has 2 IPv6 addresses and answers on every one we tested. ✓ 2001:1838:2000:41b::80:0 answers · 443✓ 2001:5a8:601:7::80:0 answers · 443	yes
Mail servers (MX) have IPv6 None of the mail servers has an AAAA record. mx0.chi1.ntfo.org ✗	no
Nameservers have IPv6 2 of 4 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up. dns1.udel.edu ✗ns1.everett.org ✓anyns.pch.net ✓dns2.udel.edu ✗	yes

What's keeping ntp.org from an A

Mail servers without IPv6
mx0.chi1.ntfo.org has no AAAA record, so mail from IPv6-only servers can't reach it directly. If a provider runs your mail, that's their setting; if you run it, add AAAA records for these hosts.

Check again

ntp.org Has IPv6

A (IPv4)	209.148.110.246 204.93.207.22
AAAA (IPv6)	2001:1838:2000:41b::80:0

www.ntp.org Has IPv6

A (IPv4)	204.93.207.22 209.148.110.246
AAAA (IPv6)	2001:1838:2000:41b::80:0 2001:5a8:601:7::80:0

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: ntp.org
Measured 2026-10-30 15:56:38 UTC by aaaa.bot (one server on Fly.io, region iad)

A (IPv4):    209.148.110.246, 204.93.207.22
AAAA (IPv6): 2001:1838:2000:41b::80:0
www AAAA:    2001:1838:2000:41b::80:0, 2001:5a8:601:7::80:0

Readiness grade B: Works over IPv6, with one gap: its mail servers lack IPv6.
- Website over IPv6: ntp.org has an AAAA record and answers on it.
    2001:1838:2000:41b::80:0: answers (TCP 443)
- www over IPv6: www.ntp.org has 2 IPv6 addresses and answers on every one we tested.
    2001:1838:2000:41b::80:0: answers (TCP 443)
    2001:5a8:601:7::80:0: answers (TCP 443)
- Mail servers (MX) have IPv6: None of the mail servers has an AAAA record.
- Nameservers have IPv6: 2 of 4 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).
No TLS or HTTP request was made.
DNS answers via DNS-over-HTTPS (Cloudflare). Method: https://aaaa.bot/method
Permanent link: https://aaaa.bot/r/Wd1AEpk2nN

Permanent link: aaaa.bot/r/Wd1AEpk2nN · How we measure

Checked 2026-10-30 15:56:38 UTC — one of the top 1,000 sites, re-checked weekly. Re-check now. Full DNS report: dns.pizza/domain/ntp.org · JSON: /api/v1/ntp.org