Apex domains cannot have CNAME records.
Question and response
Question
dig btlatam.com.br. NS
Answer
btlatam.com.br. 4 NS ns3.sencinet.com.br.
btlatam.com.br. 4 NS ns2.sencinet.com.br.
btlatam.com.br. 4 NS ns1.sencinet.com.br.
Authority
The response has no authority records.
Additional
ns1.sencinet.com.br. 4 A 200.219.160.3
ns2.sencinet.com.br. 4 A 200.219.160.4
ns3.sencinet.com.br. 4 A 200.219.167.214
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0