Apex domains cannot have CNAME records.
Question and response
Question
dig nethys.be. NS
Answer
nethys.be. 1 NS ns1.register.be.
nethys.be. 1 NS ns3.register.be.
nethys.be. 1 NS ns2.register.be.
Authority
The response has no authority records.
Additional
ns1.register.be. 1 A 86.39.202.67
ns2.register.be. 1 A 89.44.166.48
ns3.register.be. 1 A 83.217.73.172
ns1.register.be. 1 AAAA 2001:1598:0:101:0:0:0:3
ns2.register.be. 1 AAAA 2a00:1c98:50:0:0:0:0:50
ns3.register.be. 1 AAAA 2a00:1c98:0:0:0:0:53:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0