Apex domains cannot have CNAME records.
Question and response
Question
dig netturbo.com.br. NS
Answer
netturbo.com.br. 5 NS ns-1840.awsdns-38.co.uk.
netturbo.com.br. 5 NS ns-749.awsdns-29.net.
netturbo.com.br. 5 NS ns-235.awsdns-29.com.
netturbo.com.br. 5 NS ns-1409.awsdns-48.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0