Yes, this is correct. PubMed is self hosted in a datacenter located within NLM on the NIH campus. They also have their own fiber connections as you mentioned.

Yes, this is correct. PubMed is self hosted in a datacenter located within NLM on the NIH campus. They also have their own fiber connections as you mentioned. There is also a legit storage vault located within the building that houses non digital records. We were told that there were medical records going back thousands of years kept there; and possibly as far back as the Egyptian era.