mail.pnet-mail.com.br has no CNAME records.
Question and response
Question
dig mail.pnet-mail.com.br. NS
Answer
The response has no answer records.
Authority
pnet-mail.com.br. 10800 SOA ns1.predialnet.com.br. sistemas.predialnet.com.br. 2026020401 3600 1800 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0