Apex domains cannot have CNAME records.
Question and response
Question
dig ivcert.net. NS
Answer
ivcert.net. 5 NS ns1.ivnosys.net.
ivcert.net. 5 NS ns3.ivnosys.net.
ivcert.net. 5 NS ns2.ivnosys.net.
Authority
The response has no authority records.
Additional
ns1.ivnosys.net. 5 A 178.255.229.147
ns2.ivnosys.net. 5 A 18.101.78.209
ns3.ivnosys.net. 5 A 173.249.51.112
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0