Apex domains cannot have CNAME records.
Question and response
Question
dig iristransport.com. NS
Answer
iristransport.com. 3 NS ns2.iristransport.net.
iristransport.com. 3 NS ns1.iristransport.net.
iristransport.com. 3 NS ns4.iristransport.net.
iristransport.com. 3 NS ns3.iristransport.net.
Authority
The response has no authority records.
Additional
ns1.iristransport.net. 3 A 204.29.15.198
ns2.iristransport.net. 3 A 204.29.15.196
ns3.iristransport.net. 3 A 204.29.12.162
ns4.iristransport.net. 3 A 204.29.12.163
ns1.iristransport.net. 3 AAAA 2607:f920:0:1:0:0:0:2
ns2.iristransport.net. 3 AAAA 2607:f920:0:1:0:0:0:3
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0