Apex domains cannot have CNAME records.
Question and response
Question
dig dynamic.voo.be. NS
Answer
dynamic.voo.be. 5 NS brutele02.brutele.be.
dynamic.voo.be. 5 NS brutele01.brutele.be.
Authority
The response has no authority records.
Additional
brutele01.brutele.be. 5 A 185.3.160.71
brutele02.brutele.be. 5 A 185.3.160.72
brutele01.brutele.be. 5 AAAA 2a02:2788:fff5:2:0:0:0:71
brutele02.brutele.be. 5 AAAA 2a02:2788:fff5:2:0:0:0:72
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0