Apex domains cannot have CNAME records.
Question and response
Question
dig nitronewsmail.com.br. NS
Answer
nitronewsmail.com.br. 5 NS ns-1329.awsdns-38.org.
nitronewsmail.com.br. 5 NS ns-298.awsdns-37.com.
nitronewsmail.com.br. 5 NS ns-1014.awsdns-62.net.
nitronewsmail.com.br. 5 NS ns-1578.awsdns-05.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0