Apex domains cannot have CNAME records.
Question and response
Question
dig apprendrefrancaisviaskype.com. NS
Answer
apprendrefrancaisviaskype.com. 5 NS ns1.apprendrefrancaisviaskype.com.
apprendrefrancaisviaskype.com. 5 NS ns2.apprendrefrancaisviaskype.com.
Authority
The response has no authority records.
Additional
ns1.apprendrefrancaisviaskype.com. 5 A 15.204.244.215
ns2.apprendrefrancaisviaskype.com. 5 A 15.204.145.176
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0