Apex domains cannot have CNAME records.
Question and response
Question
dig vivre-sans-fumee.com. NS
Answer
vivre-sans-fumee.com. 5 NS ns2.vivre-sans-fumee.com.
vivre-sans-fumee.com. 5 NS ns1.vivre-sans-fumee.com.
Authority
The response has no authority records.
Additional
ns1.vivre-sans-fumee.com. 5 A 192.99.69.233
ns2.vivre-sans-fumee.com. 5 A 51.161.57.73
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0