Apex domains cannot have CNAME records.
Question and response
Question
dig desktop.com.br. NS
Answer
desktop.com.br. 5 NS dns1.desktop.com.br.
desktop.com.br. 5 NS dns2.desktop.com.br.
Authority
The response has no authority records.
Additional
dns1.desktop.com.br. 5 A 201.77.112.18
dns2.desktop.com.br. 5 A 201.77.112.19
dns1.desktop.com.br. 5 AAAA 2804:868:2:0:0:0:0:18
dns2.desktop.com.br. 5 AAAA 2804:868:2:0:0:0:0:19
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0