mx4.ovh.net has no NS records.
NS records for this zone are defined at ovh.net.
NS records for this zone are defined at ovh.net.
Question and response
Question
dig mx4.ovh.net. NS
Answer
The response has no answer records.
Authority
ovh.net. 60 SOA dns10.ovh.net. tech.ovh.net. 2026022609 86400 3600 3600000 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0