Apex domains cannot have CNAME records.
Question and response
Question
dig page-educ.fr. NS
Answer
page-educ.fr. 5 NS ns-92-b.gandi.net.
page-educ.fr. 5 NS ns-117-a.gandi.net.
page-educ.fr. 5 NS ns-176-c.gandi.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0