www.ncbi.nlm.nih.gov / pubmed

[Phil Mayers]

On 18/08/10 13:15, Lightner, Jeff wrote:
> It comes right up in Firefox but prompts for a username and password.

Do you have DNSSEC validation enabled? Because as per my email, it's a 
DNSSEC problem.

After a bit of investigation, it seems that the problem is a missing 
NSEC/NSEC3 record in the empty reply for:

$ dig +dnssec @165.112.4.230 ncbi.nlm.nih.gov ds

...since the "ncbi" zone is an unsigned child zone, there needs to be an 
NSEC/NSEC3 record to prove the absence of the DS record, and have a 
secure delegation to an unsigned child zone.