Apex domains cannot have CNAME records.
Question and response
Question
dig edpnet.net. NS
Answer
edpnet.net. 5 NS ns2.edpnet.be.
edpnet.net. 5 NS ns1.edpnet.be.
Authority
The response has no authority records.
Additional
ns1.edpnet.be. 5 A 212.71.0.2
ns2.edpnet.be. 5 A 212.71.8.11
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0