mxbackup.eolas-services.com has no CNAME records.
Question and response
Question
dig mxbackup.eolas-services.com. NS
Answer
The response has no answer records.
Authority
eolas-services.com. 2455 SOA dnsmaster.eolas-services.com. postmaster.eolas.fr. 2025101483 1200 900 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0