Apex domains cannot have CNAME records.
Question and response
Question
dig thz.host. NS
Answer
thz.host. 5 NS dns3.thzhost.com.
thz.host. 5 NS dns1.thzhost.com.
thz.host. 5 NS dns2.thzhost.com.
thz.host. 5 NS dns4.thzhost.com.
Authority
The response has no authority records.
Additional
dns1.thzhost.com. 5 A 139.59.194.51
dns2.thzhost.com. 5 A 103.246.18.126
dns3.thzhost.com. 5 A 192.241.253.185
dns4.thzhost.com. 5 A 95.85.22.186
dns1.thzhost.com. 5 AAAA 2400:6180:0:d0:0:0:1b2:9001
dns2.thzhost.com. 5 AAAA 2401:5700:100:503:0:0:0:126
dns3.thzhost.com. 5 AAAA 2604:a880:0:1010:0:0:12ec:3001
dns4.thzhost.com. 5 AAAA 2a03:b0c0:0:1010:0:0:2d:6001
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0