Apex domains cannot have CNAME records.
Question and response
Question
dig static.sumicity.net.br. NS
Answer
static.sumicity.net.br. 4 NS ptr1.sumicity.net.br.
static.sumicity.net.br. 4 NS 10.99.2.26.
static.sumicity.net.br. 4 NS ptr2.sumicity.net.br.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0