mxsy.beeline.ru has no CNAME records.
Question and response
Question
dig mxsy.beeline.ru. NS
Answer
The response has no answer records.
Authority
beeline.ru. 6146 SOA ns1.beeline.ru. mgribkov.beeline.ru. 2025031529 1200 120 864000 43200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0