Apex domains cannot have CNAME records.
Question and response
Question
dig netecom.com.br. NS
Answer
netecom.com.br. 4 NS ns01.netecom.com.br.
netecom.com.br. 4 NS ns02.netecom.com.br.
Authority
The response has no authority records.
Additional
ns01.netecom.com.br. 4 A 177.86.159.253
ns02.netecom.com.br. 4 A 177.86.159.254
ns01.netecom.com.br. 4 AAAA 2804:1448:0:dd:0:0:0:253
ns02.netecom.com.br. 4 AAAA 2804:1448:0:dd:0:0:0:254
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0