Apex domains cannot have CNAME records.
Question and response
Question
dig sitel.com.br. NS
Answer
sitel.com.br. 4 NS ns2.sitel.com.br.
sitel.com.br. 4 NS ns1.sitel.com.br.
Authority
The response has no authority records.
Additional
ns1.sitel.com.br. 4 A 187.103.160.23
ns2.sitel.com.br. 4 A 187.103.160.24
ns1.sitel.com.br. 4 AAAA 2804:928:1:0:0:0:0:23
ns2.sitel.com.br. 4 AAAA 2804:928:1:0:0:0:0:24
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0