Apex domains cannot have CNAME records.
Question and response
Question
dig antispam.redehost.com.br. NS
Answer
antispam.redehost.com.br. 5 NS redehostdns06.redehost.com.br.
antispam.redehost.com.br. 5 NS redehostdns05.redehost.com.br.
Authority
The response has no authority records.
Additional
redehostdns05.redehost.com.br. 5 A 187.84.225.3
redehostdns06.redehost.com.br. 5 A 177.55.96.14
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0