Apex domains cannot have CNAME records.
Question and response
Question
dig as51514.com. NS
Answer
as51514.com. 5 NS ns1.as51514.com.
as51514.com. 5 NS ns1.as51514.net.
as51514.com. 5 NS ns1.as51514.co.uk.
as51514.com. 5 NS ns1.as51514.us.
Authority
The response has no authority records.
Additional
ns1.as51514.co.uk. 5 A 178.79.187.200
ns1.as51514.us. 5 A 45.33.92.242
ns1.as51514.com. 5 A 172.104.185.152
ns1.as51514.net. 5 A 46.31.48.200
ns1.as51514.co.uk. 5 AAAA 2a01:7e00:0:0:f03c:91ff:fe62:f594
ns1.as51514.us. 5 AAAA 2600:3c03:0:0:f03c:91ff:fe62:6e9b
ns1.as51514.com. 5 AAAA 2400:8901:0:0:f03c:91ff:fe62:b2cb
ns1.as51514.net. 5 AAAA 2a02:23e8:100:53:0:0:48:200
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0