Apex domains cannot have CNAME records.
Question and response
Question
dig uailinknet.com.br. NS
Answer
uailinknet.com.br. 4 NS dns2.orbitelecom.com.br.
uailinknet.com.br. 4 NS dns1.orbitelecom.com.br.
Authority
The response has no authority records.
Additional
dns1.orbitelecom.com.br. 4 A 45.184.16.253
dns2.orbitelecom.com.br. 4 A 45.184.16.254
dns1.orbitelecom.com.br. 4 AAAA 2804:62a0:aa:0:0:0:0:aa
dns2.orbitelecom.com.br. 4 AAAA 2804:62a0:aa:0:0:0:0:ab
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0