Apex domains cannot have CNAME records.
Question and response
Question
dig ktree.com.br. NS
Answer
ktree.com.br. 5 NS ns2.penso.com.br.
ktree.com.br. 5 NS ns3.penso.com.br.
ktree.com.br. 5 NS ns1.penso.com.br.
Authority
The response has no authority records.
Additional
ns1.penso.com.br. 5 A 200.219.235.30
ns2.penso.com.br. 5 A 201.20.9.69
ns3.penso.com.br. 5 A 177.184.27.100
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0