Apex domains cannot have CNAME records.
Question and response
Question
dig cetelem.com.br. NS
Answer
cetelem.com.br. 5 NS a18-66.akam.net.
cetelem.com.br. 5 NS a28-64.akam.net.
cetelem.com.br. 5 NS ns2.cetelem.com.br.
cetelem.com.br. 5 NS a1-15.akam.net.
cetelem.com.br. 5 NS ns1.cetelem.com.br.
cetelem.com.br. 5 NS a3-65.akam.net.
cetelem.com.br. 5 NS a7-66.akam.net.
cetelem.com.br. 5 NS a24-67.akam.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0