mx2.perf1.fr has no CNAME records.
Question and response
Question
dig mx2.perf1.fr. NS
Answer
The response has no answer records.
Authority
perf1.fr. 5920 SOA nsa.perf1.fr. technical.nameshield.net. 2026021901 28800 7200 604800 7200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0