Apex domains cannot have CNAME records.
Question and response
Question
dig datacenter1.com.br. NS
Answer
datacenter1.com.br. 1 NS a.auto.dns.br.
datacenter1.com.br. 1 NS b.auto.dns.br.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0