Apex domains cannot have CNAME records.
Question and response
Question
dig centralnic-dns.com. NS
Answer
centralnic-dns.com. 5 NS ns1.centralnic.net.
centralnic-dns.com. 5 NS ns4.centralnic.net.
centralnic-dns.com. 5 NS ns3.centralnic.net.
centralnic-dns.com. 5 NS ns2.centralnic.net.
Authority
The response has no authority records.
Additional
ns1.centralnic.net. 5 A 194.169.218.24
ns2.centralnic.net. 5 A 185.24.64.10
ns3.centralnic.net. 5 A 212.18.248.10
ns4.centralnic.net. 5 A 212.18.249.24
ns1.centralnic.net. 5 AAAA 2001:67c:13cc:0:0:0:1:24
ns2.centralnic.net. 5 AAAA 2a04:2b00:13cc:0:0:0:1:10
ns3.centralnic.net. 5 AAAA 2a04:2b00:13ee:0:0:0:0:10
ns4.centralnic.net. 5 AAAA 2a04:2b00:13ff:0:0:0:0:24
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0