mx2.com4datacenter.com.br has no CNAME records.
Question and response
Question
dig mx2.com4datacenter.com.br. NS
Answer
The response has no answer records.
Authority
com4datacenter.com.br. 3371 SOA dns1.com4.com.br. hostmaster.com4.com.br. 291 900 600 86400 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0