not-usable has no NS records.
NS records for this zone are defined at not-usable..
NS records for this zone are defined at not-usable..
Question and response
Question
dig not-usable. NS
Answer
The response has no answer records.
Authority
. 86400 SOA a.root-servers.net. nstld.verisign-grs.com. 2026031100 1800 900 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0