mailsender.inetcom.ru has no CNAME records.
Question and response
Question
dig mailsender.inetcom.ru. NS
Answer
The response has no answer records.
Authority
inetcom.ru. 6863 SOA ns1.inetcom.ru. dnsmaster.inetcom.ru. 738578201 86400 900 1814400 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0