mail2.intersvyaz.net has no CNAME records.
Question and response
Question
dig mail2.intersvyaz.net. NS
Answer
The response has no answer records.
Authority
intersvyaz.net. 10800 SOA ns1.is74.ru. hostmaster.is74.ru. 2018071827 10800 1800 604801 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0