Apex domains cannot have CNAME records.
Question and response
Question
dig rain.fr. NS
Answer
rain.fr. 5 NS dns2.equant.net.
rain.fr. 5 NS dns3.equant.net.
rain.fr. 5 NS dns1.equant.net.
Authority
The response has no authority records.
Additional
dns1.equant.net. 5 A 57.67.127.194
dns2.equant.net. 5 A 57.73.127.194
dns3.equant.net. 5 A 57.68.127.194
dns1.equant.net. 5 AAAA 2a01:ce89:8000:1001:57:67:127:194
dns2.equant.net. 5 AAAA 2a01:ce9d:0:1001:57:73:127:194
dns3.equant.net. 5 AAAA 2a01:ce95:4000:1001:204:59:152:207
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0