Apex domains cannot have CNAME records.
Question and response
Question
dig hz.net.br. NS
Answer
hz.net.br. 1 NS dns1.ilcom.com.br.
hz.net.br. 1 NS dns2.ilcom.com.br.
hz.net.br. 1 NS dns3.ilcom.com.br.
hz.net.br. 1 NS dns4.ilcom.com.br.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0