Apex domains cannot have CNAME records.
Question and response
Question
dig tixui.com. NS
Answer
tixui.com. 5 NS ns2.cloudcity.fi.
tixui.com. 5 NS ns1.cloudcity.fi.
Authority
The response has no authority records.
Additional
ns1.cloudcity.fi. 5 A 185.220.76.33
ns2.cloudcity.fi. 5 A 94.237.25.23
ns1.cloudcity.fi. 5 AAAA 2a0b:f240:0:3:0:0:0:33
ns2.cloudcity.fi. 5 AAAA 2a04:3542:1000:910:bc42:40ff:fec3:7b30
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0