s4-ipv4.tronche.com has no CNAME records.
Question and response
Question
dig s4-ipv4.tronche.com. NS
Answer
The response has no answer records.
Authority
tronche.com. 1147 SOA dns16.ovh.net. tech.ovh.net. 2026012800 86400 3600 3600000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0