Apex domains cannot have CNAME records.
Question and response
Question
dig ip-145-239-71.eu. NS
Answer
ip-145-239-71.eu. 5 NS dns103.ovh.net.
ip-145-239-71.eu. 5 NS ns103.ovh.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0