Apex domains cannot have CNAME records.
Question and response
Question
dig wznet.com.br. NS
Answer
wznet.com.br. 5 NS dns-aut-02.wznet.com.br.
wznet.com.br. 5 NS dns-aut-01.wznet.com.br.
Authority
The response has no authority records.
Additional
dns-aut-01.wznet.com.br. 5 A 177.125.112.180
dns-aut-02.wznet.com.br. 5 A 177.125.112.181
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0