Apex domains cannot have CNAME records.
Question and response
Question
dig kryptonbpo.com.br. NS
Answer
kryptonbpo.com.br. 5 NS ns-187.awsdns-23.com.
kryptonbpo.com.br. 5 NS ns-680.awsdns-21.net.
kryptonbpo.com.br. 5 NS ns-1466.awsdns-55.org.
kryptonbpo.com.br. 5 NS ns-1746.awsdns-26.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0