mail-mx-2.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 mail-mx-2.ripe.net. NS
Answer
The response has no answer records.
Authority
ripe.net. 3600 SOA manus.authdns.ripe.net. dns.ripe.net. 1773758543 3600 600 864000 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0