No — nih.gov is IPv4 only.

Has an IPv4 address but no IPv6 (AAAA) record. IPv6-only visitors can't reach it directly.

D
IPv6 readiness
The website has no IPv6.
Website over IPv6
nih.gov has no AAAA record.		no
www over IPv6
www.nih.gov has 4 IPv6 addresses and answers on every one we tested.
✓ 2606:4700:78::90:0:181 answers · 443✓ 2606:4700:78::90:0:182 answers · 443✓ 2606:4700:78::90:0:183 answers · 443✓ 2606:4700:78::90:0:180 answers · 443
yes
Mail servers (MX) have IPv6
Every mail server has an AAAA record.
nihcesxway3.hub.nih.gov ✓nihcesxway4.hub.nih.gov ✓nihcesxway5.hub.nih.gov ✓nihcesxway6.hub.nih.gov ✓nihcesxwayst03.hub.nih.gov ✓nihcesxwayst04.hub.nih.gov ✓nihcesxwayst05.hub.nih.gov ✓nihcesxwayst06.hub.nih.gov ✓
yes
Nameservers have IPv6
3 of 3 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up.
ns.nih.gov ✓ns2.nih.gov ✓ns3.nih.gov ✓
yes

What's keeping nih.gov from an A

  1. Give nih.gov an IPv6 address
    Ask your hosting provider for the site's IPv6 address (or the hostname to point at), then publish it as an AAAA record. If your host doesn't offer IPv6, a proxy that does can sit in front. How to add an AAAA record

Check again

nih.gov  IPv4 only

A (IPv4)156.40.212.210
AAAA (IPv6)none

www.nih.gov  Has IPv6

Alias ofwww.nih.gov.cdn.cloudflare.net
A (IPv4)172.65.90.27
172.65.90.24
172.65.90.25
172.65.90.26
AAAA (IPv6)2606:4700:78::90:0:181
2606:4700:78::90:0:182
2606:4700:78::90:0:183
2606:4700:78::90:0:180

What this means

Visitors on IPv6-only networks (many mobile carriers) can still reach it, but only through a translator their carrier runs (NAT64). The site itself has no IPv6 address — and you can't make one up from the IPv4. Why some hosts don't offer it

Copy the evidence — a citation-ready record of this measurement

 Permanent link: aaaa.bot/r/x3ZCGZcicV · How we measure

Checked 2026-10-30 17:04:32 UTC — one of the top 1,000 sites, re-checked weekly. Re-check now. Full DNS report: dns.pizza/domain/nih.gov · JSON: /api/v1/nih.gov