Apex domains cannot have CNAME records.
Question and response
Question
dig yiptelecom.com.br. NS
Answer
yiptelecom.com.br. 4 NS ns1.contabo.net.
yiptelecom.com.br. 4 NS ns2.contabo.net.
yiptelecom.com.br. 4 NS ns3.contabo.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0