Apex domains cannot have CNAME records.
Question and response
Question
dig aclinkcertificacao.com.br. NS
Answer
aclinkcertificacao.com.br. 5 NS ns-1799.awsdns-32.co.uk.
aclinkcertificacao.com.br. 5 NS ns-63.awsdns-07.com.
aclinkcertificacao.com.br. 5 NS ns-525.awsdns-01.net.
aclinkcertificacao.com.br. 5 NS ns-1288.awsdns-33.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0