It seems someone shut down all NIH DNS servers. Right now the NIH website, PubMed and BLAST are up, but not resolvable.

Cloudflare's 1.0.0.1 DNS resolver seems to still have cached the records. Google and most others I tried did not. This probably explains why some people on social media could access the sites while others couldn't.

Workaround via /etc/hosts :

  156.40.212.210 nih.gov
  96.17.96.9     www.nih.gov
  34.107.134.59  pubmed.ncbi.nlm.nih.gov
  130.14.250.10  ftp.wip.ncbi.nlm.nih.gov
  130.14.250.10  ftp.ncbi.nlm.nih.gov
  130.14.29.110  blast.ncbi.nlm.nih.gov

EDIT:

While ns.nih.gov, ns2.nih.gov, and ns3.nih.gov do not respond, the nameserver at lhcns1.nlm.nih.gov (130.14.55.72) does.

Also see https://tldr.nettime.org/@ww/114089972404202687