mx2.omkc.RU has no CNAME records.
Question and response
Question
dig mx2.omkc.RU. NS
Answer
The response has no answer records.
Authority
omkc.RU. 2622 SOA ns.omkc.RU. root.ns.omkc.RU. 2026021704 3600 900 360000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0