Apex domains cannot have CNAME records.
Question and response
Question
dig hdcloud.com.br. NS
Answer
hdcloud.com.br. 5 NS ns-599.awsdns-10.net.
hdcloud.com.br. 5 NS ns-175.awsdns-21.com.
hdcloud.com.br. 5 NS ns-1970.awsdns-54.co.uk.
hdcloud.com.br. 5 NS ns-1241.awsdns-27.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0