cluster021.hosting.ovh.net has no CNAME records.
Question and response
Question
dig cluster021.hosting.ovh.net. NS
Answer
The response has no answer records.
Authority
hosting.ovh.net. 60 SOA dns18.ovh.net. tech.ovh.net. 2026022505 86400 3600 3600000 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0