mail.bsh.ru has no CNAME records.
Question and response
Question
dig mail.bsh.ru. NS
Answer
The response has no answer records.
Authority
bsh.ru. 3060 SOA ns.bsh.ru. noc.bsh.ru. 2026020436 1800 300 2419200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0