mail.erectaat.com has no CNAME records.
Question and response
Question
dig mail.erectaat.com. NS
Answer
The response has no answer records.
Authority
erectaat.com. 5386 SOA ns1.erectacloud.it. domini.erectaat.com. 2025121103 43200 7200 2419200 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0