mail2.delta-telecom.net has no CNAME records.
Question and response
Question
dig mail2.delta-telecom.net. NS
Answer
The response has no answer records.
Authority
delta-telecom.net. 10800 SOA ns1.azersat.com. webmaster.delta-telecom.net. 2026030904 43200 7200 2419200 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0