Apex domains cannot have CNAME records.
Question and response
Question
dig ip-217-182-158.eu. NS
Answer
ip-217-182-158.eu. 5 NS ns17.ovh.net.
ip-217-182-158.eu. 5 NS dns17.ovh.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0