mx003.samtel.ru has no CNAME records.
Question and response
Question
dig mx003.samtel.ru. NS
Answer
The response has no answer records.
Authority
samtel.ru. 5833 SOA ns1.samtel.ru. root.samtel.ru. 2026021801 28800 3600 1814400 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0