Apex domains cannot have CNAME records.
Question and response
Question
dig directtalk.com.br. NS
Answer
directtalk.com.br. 5 NS ns-1844.awsdns-38.co.uk.
directtalk.com.br. 5 NS ns-1263.awsdns-29.org.
directtalk.com.br. 5 NS ns-37.awsdns-04.com.
directtalk.com.br. 5 NS ns-932.awsdns-52.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0