mail.central01.net has no CNAME records.
Question and response
Question
dig mail.central01.net. NS
Answer
The response has no answer records.
Authority
central01.net. 3216 SOA ns1.central01.net. joaopaulo.central01.net. 2026010501 3600 900 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0