mxu.BEELINE.RU has no CNAME records.
Question and response
Question
dig mxu.BEELINE.RU. NS
Answer
The response has no answer records.
Authority
beeline.ru. 4949 SOA ns1.beeline.ru. mgribkov.beeline.ru. 2025031524 1200 120 864000 43200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0