mail.MASTERTELECOM.RU has no CNAME records.
Question and response
Question
dig mail.MASTERTELECOM.RU. NS
Answer
The response has no answer records.
Authority
MASTERTELECOM.RU. 1662 SOA ns1.mastertel.RU. noc.mastertel.RU. 2024122300 10800 3600 3600000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0