Apex domains cannot have CNAME records.
Question and response
Question
dig LESTETELECOM.COM.BR. NS
Answer
lestetelecom.com.br. 5 NS ns02.leste.com.br.lestetelecom.com.br.
lestetelecom.com.br. 5 NS ns03.leste.com.br.lestetelecom.com.br.
lestetelecom.com.br. 5 NS ns04.leste.com.br.lestetelecom.com.br.
lestetelecom.com.br. 5 NS ns01.leste.com.br.lestetelecom.com.br.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0