mx.vks-it.ru has no CNAME records.
Question and response
Question
dig mx.vks-it.ru. NS
Answer
The response has no answer records.
Authority
vks-it.ru. 300 SOA ns1.beget.com. hostmaster.beget.com. 1684715509 300 600 86400 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0