Apex domains cannot have CNAME records.
Question and response
Question
dig linkbrasil.net.br. NS
Answer
linkbrasil.net.br. 5 NS blair.ns.cloudflare.com.
linkbrasil.net.br. 5 NS karl.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0