Apex domains cannot have CNAME records.
Question and response
Question
dig cloudgouv-eu-west-1.compute.outscale.com. NS
Answer
cloudgouv-eu-west-1.compute.outscale.com. 3 NS sec1-ns2.outscale.net.
cloudgouv-eu-west-1.compute.outscale.com. 3 NS sec1-ns1.outscale.net.
Authority
The response has no authority records.
Additional
sec1-ns1.outscale.net. 2 A 185.21.195.130
sec1-ns2.outscale.net. 2 A 185.21.195.131
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0