mx4.mail.ovh.net has no NS records.
NS records for this zone are defined at mail.ovh.net.
NS records for this zone are defined at mail.ovh.net.
Question and response
Question
dig mx4.mail.ovh.net. NS
Answer
The response has no answer records.
Authority
mail.ovh.net. 60 SOA dns10.ovh.net. tech.ovh.net. 2026030306 86400 3600 3600000 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0