Apex domains cannot have CNAME records.
Question and response
Question
dig hostreverse.com.br. NS
Answer
hostreverse.com.br. 1 NS ns3.he.net.
hostreverse.com.br. 1 NS ns5.he.net.
hostreverse.com.br. 1 NS ns2.he.net.
hostreverse.com.br. 1 NS ns1.he.net.
hostreverse.com.br. 1 NS ns4.he.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0