Apex domains cannot have CNAME records.
Question and response
Question
dig algodata.fr. NS
Answer
algodata.fr. 5 NS ns-70.awsdns-08.com.
algodata.fr. 5 NS ns-1801.awsdns-33.co.uk.
algodata.fr. 5 NS ns-1506.awsdns-60.org.
algodata.fr. 5 NS ns-688.awsdns-22.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0