ns01.refeduc.com.br has no CNAME records.
Question and response
Question
dig ns01.refeduc.com.br. NS
Answer
The response has no answer records.
Authority
refeduc.com.br. 2676 SOA ns1-34.azure-dns.com. hostmaster.franciscanos.net. 2016111252 1200 600 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0