Apex domains cannot have CNAME records.
Question and response
Question
dig corp.wznet.com.br. NS
Answer
corp.wznet.com.br. 5 NS ns2.he.net.
corp.wznet.com.br. 5 NS ns3.he.net.
corp.wznet.com.br. 5 NS dns-aut-01.corp.wznet.com.br.
corp.wznet.com.br. 5 NS ns5.he.net.
corp.wznet.com.br. 5 NS ns4.he.net.
corp.wznet.com.br. 5 NS dns-aut-02.corp.wznet.com.br.
Authority
The response has no authority records.
Additional
ns2.he.net. 4 A 216.218.131.2
ns3.he.net. 4 A 216.218.132.2
ns4.he.net. 4 A 216.66.1.2
ns5.he.net. 4 A 216.66.80.18
ns2.he.net. 4 AAAA 2001:470:200:0:0:0:0:2
ns3.he.net. 4 AAAA 2001:470:300:0:0:0:0:2
ns4.he.net. 4 AAAA 2001:470:400:0:0:0:0:2
ns5.he.net. 4 AAAA 2001:470:500:0:0:0:0:2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0