DNS NS Records

DNS nameserver (NS) records are used to describe the authoritative nameservers for a particular domain. They are a vital part of DNS and what allows for distributed zone management.

E.g.
Here we can see nameservers for un.org:

% dig un.org ns +short
ns2.un.org.
ns1.un.org.
ns3.un.org.
%
This tells the DNS resolver that for DNS resolution in the un.org domain, it should reach out to one of those three nameservers.