mx3.teccloud.com.br has no CNAME records.
Question and response
Question
dig mx3.teccloud.com.br. NS
Answer
The response has no answer records.
Authority
teccloud.com.br. 2861 SOA ns2.teccloud.com. dominios.teccloud.com.br. 2024082601 10800 3600 2419200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0