Apex domains cannot have CNAME records.
Question and response
Question
dig successinet.com. NS
Answer
successinet.com. 5 NS ns1.successinet.com.
successinet.com. 5 NS ns2.successinet.com.
Authority
The response has no authority records.
Additional
ns1.successinet.com. 5 A 188.40.184.211
ns2.successinet.com. 5 A 178.63.186.107
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0