Apex domains cannot have CNAME records.
Question and response
Question
dig liggatelecom.com.br. NS
Answer
liggatelecom.com.br. 5 NS ns1.a2.impervasecuredns.net.
liggatelecom.com.br. 5 NS ns1.a0.impervasecuredns.net.
liggatelecom.com.br. 5 NS ns1.a1.impervasecuredns.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0