Yes — loc.gov has IPv6.

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

This is a saved measurement from 2026-10-31 12:31 UTC. Check loc.gov live now

B
IPv6 readiness
Works over IPv6, with one gap: its mail servers lack IPv6.
Website over IPv6
loc.gov has 2 IPv6 addresses and answers on every one we tested.
✓ 2606:4700::6811:63a answers · 443✓ 2606:4700::6812:4052 answers · 443
yes
www over IPv6
www.loc.gov has 2 IPv6 addresses and answers on every one we tested.
✓ 2606:4700::6812:4052 answers · 443✓ 2606:4700::6811:63a answers · 443
yes
Mail servers (MX) have IPv6
None of the mail servers has an AAAA record.
mxa-00026101.gslb.gpphosted.com ✗mxb-00026101.gslb.gpphosted.com ✗
no
Nameservers have IPv6
2 of 2 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up.
alice.ns.cloudflare.com ✓kevin.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://loc.gov/ via 2606:4700::6811:63a → 301https://www.loc.gov/ via 2606:4700::6812:4052 → 200
works

What's keeping loc.gov from an A

  1. Mail servers without IPv6
    mxa-00026101.gslb.gpphosted.com, mxb-00026101.gslb.gpphosted.com 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

loc.gov  Has IPv6

A (IPv4)104.17.6.58
104.18.64.82
AAAA (IPv6)2606:4700::6811:63a
2606:4700::6812:4052

www.loc.gov  Has IPv6

A (IPv4)104.17.6.58
104.18.64.82
AAAA (IPv6)2606:4700::6812:4052
2606:4700::6811:63a

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

 Permanent link: aaaa.bot/r/xtgBG5KfgN · How we measure

Checked 2026-10-31 12:31:13 UTC. Full DNS report: dns.pizza/domain/loc.gov · JSON: /api/v1/loc.gov