sec2.authdns.ripe.net has no NS records.
NS records for this zone are defined at ripe.net.
NS records for this zone are defined at ripe.net.
Question and response
Question
dig sec2.authdns.ripe.net. NS
Answer
The response has no answer records.
Authority
ripe.net. 3600 SOA manus.authdns.ripe.net. dns.ripe.net. 1772550982 3600 600 864000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0