Apex domains cannot have CNAME records.
Question and response
Question
dig cms-france.net. NS
Answer
cms-france.net. 5 NS ns1.cms-france.net.
cms-france.net. 5 NS ns3.cms-france.net.
cms-france.net. 5 NS ns2.cms-france.net.
Authority
The response has no authority records.
Additional
ns1.cms-france.net. 5 A 62.210.160.243
ns2.cms-france.net. 5 A 213.152.5.84
ns3.cms-france.net. 5 A 195.154.66.49
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0