mail02.regiocom.net has no CNAME records.
Question and response
Question
dig mail02.regiocom.net. NS
Answer
The response has no answer records.
Authority
regiocom.net. 600 SOA ns1.regiocom.net. hostmaster.regiocom.net. 2026030502 400 10800 36000000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0