Apex domains cannot have CNAME records.
Question and response
Question
dig leaseweb.org. NS
Answer
leaseweb.org. 5 NS ns1.leaseweb.nl.
leaseweb.org. 5 NS ns4.leaseweb.net.
leaseweb.org. 5 NS ns5.leaseweb.nl.
Authority
The response has no authority records.
Additional
ns1.leaseweb.nl. 5 A 23.19.196.53
ns5.leaseweb.nl. 5 A 23.19.197.53
ns5.leaseweb.nl. 5 AAAA 2607:f5b5:1:0:0:0:0:53
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0