mail.design.ru has no CNAME records.
Question and response
Question
dig mail.design.ru. NS
Answer
The response has no answer records.
Authority
design.ru. 1800 SOA ns.design.ru. noc.design.ru. 2026021901 1800 900 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0