dnsns — look up the name server records of a domain name
dnsns {fqdn...}
dnsns looks up the NS resource records for fqdn in the Domain Name System, and prints them.
Normally dnsns exits 0.
If it encounters a temporary problem that prevents it from determining the NS resource records, it prints an error message and exits 111.
dnsns makes all DNS lookups using the locally configured DNS proxy server(s), and performs no name qualification on what is taken to already be a "fully-qualified" domain name (trailing dot or no) fqdn.
See djbdns-client(5) for how this server is found, and for certain standard domain names that short-circuit DNS lookups to the proxy DNS server(s).
fqdn can take the appearance of the human-readable form of a (legal and well-formed) IPv4 address.
However, it is always considered to be a domain name and passed to the locally configured proxy DNS server(s) for lookup.
dnscache(1) filters queries for such names and synthesizes fixed responses to them that list no NS resource records.
Other proxy DNS servers rely upon the fact that the public "." content DNS servers state that these domains do not exist, and generate bogus traffic to those servers.