Apex domains cannot have CNAME records.
Question and response
Question
dig lpnet.com.br. NS
Answer
lpnet.com.br. 5 NS dns1.lpnet.com.br.
lpnet.com.br. 5 NS dns4.lpnet.com.br.
lpnet.com.br. 5 NS dns3.lpnet.com.br.
lpnet.com.br. 5 NS dns2.lpnet.com.br.
Authority
The response has no authority records.
Additional
dns1.lpnet.com.br. 5 A 189.1.144.228
dns2.lpnet.com.br. 5 A 189.1.144.229
dns1.lpnet.com.br. 5 AAAA 2804:4ec:1:0:0:0:0:228
dns2.lpnet.com.br. 5 AAAA 2804:4ec:1:0:0:0:0:229
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0