mx01.thalesgroup.com has no CNAME records.
Question and response
Question
dig mx01.thalesgroup.com. NS
Answer
The response has no answer records.
Authority
thalesgroup.com. 823 SOA ns1.thalesgroup.com. operateur-dns.thalesgroup.com. 2026022095 21600 3600 3600000 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0