Apex domains cannot have CNAME records.
Question and response
Question
dig eu-west-2.compute.outscale.com. NS
Answer
eu-west-2.compute.outscale.com. 5 NS par1-ns2.outscale.net.
eu-west-2.compute.outscale.com. 5 NS par1-ns1.outscale.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0