The most accessible tool I would recommend is zonemaster.net, a tool developed by AFNIC and The Swedish Internet Foundation. Go to advanced and type in nlm.nih.gov as ___domain, and then the two nameservers listed above and their ip addresses. Run the test and it will present a status summery of the ___domain and its name servers. (or just use this link: https://zonemaster.net/en/result/4a7d593dce6e167b)
Alternatively you can use the tool dig command tool which is the industry standard for dns debugging and probing. Installing it on windows/mac is a bit of work, but is very easy and convenient on linux. The command here would be "dig @130.14.55.128 nlm.nih.gov". The @ sign is for saying which nameserver to use, and the last part is the ___domain name you are looking for.
I can't ping 130.14.55.128