ns2.zcdn.RU has no MX records.
Question and response
Question
dig ns2.zcdn.RU. MX
Answer
The response has no answer records.
Authority
zcdn.ru. 10800 SOA ns2.zcdn.ru. adm.zcdn.ru. 2025092618 14400 7200 2419200 10800
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0