Apex domains cannot have CNAME records.
Question and response
Question
dig 975048a0-idc.pto.dinpto.com.br. NS
Answer
975048a0-idc.pto.dinpto.com.br. 5 NS ns2.dnzdns.com.
975048a0-idc.pto.dinpto.com.br. 5 NS ns1.dnzdns.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0