Apex domains cannot have CNAME records.
Question and response
Question
dig novagraaf-dns.com. NS
Answer
novagraaf-dns.com. 5 NS dns4.novagraaf-dns.eu.
novagraaf-dns.com. 5 NS dns2.novagraaf-dns.net.
novagraaf-dns.com. 5 NS dns1.novagraaf-dns.com.
novagraaf-dns.com. 5 NS dns3.novagraaf-dns.nl.
Authority
The response has no authority records.
Additional
dns1.novagraaf-dns.com. 5 A 198.51.44.11
dns2.novagraaf-dns.net. 5 A 198.51.45.11
dns3.novagraaf-dns.nl. 5 A 198.51.44.75
dns4.novagraaf-dns.eu. 5 A 198.51.45.75
dns1.novagraaf-dns.com. 5 AAAA 2620:4d:4000:6259:7:11:0:1
dns2.novagraaf-dns.net. 5 AAAA 2a00:edc0:6259:7:11:0:0:2
dns3.novagraaf-dns.nl. 5 AAAA 2620:4d:4000:6259:7:11:0:3
dns4.novagraaf-dns.eu. 5 AAAA 2a00:edc0:6259:7:11:0:0:4
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0