mx2.eserver-ru.com has no CNAME records.
Question and response
Question
dig mx2.eserver-ru.com. NS
Answer
The response has no answer records.
Authority
eserver-ru.com. 1720 SOA ns1.cit-network.net. hostmaster.eserver.ru. 1746804452 7200 3600 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0