mx4.avantel.ru has no CNAME records.
Question and response
Question
dig mx4.avantel.ru. NS
Answer
The response has no answer records.
Authority
avantel.ru. 3126 SOA ns.avantel.ru. support.avantel.ru. 2026021204 3600 1800 43200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0