Apex domains cannot have CNAME records.
Question and response
Question
dig wfibra.com.br. NS
Answer
wfibra.com.br. 4 NS ns2.wfibra.com.br.
wfibra.com.br. 4 NS ns1.wfibra.com.br.
Authority
The response has no authority records.
Additional
ns1.wfibra.com.br. 4 A 138.99.132.14
ns2.wfibra.com.br. 4 A 138.99.132.18
ns1.wfibra.com.br. 4 AAAA 2804:2454:133:0:0:0:0:2
ns2.wfibra.com.br. 4 AAAA 2804:2454:133:0:0:0:0:10
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0