mail.netorn.net has no CNAME records.
Question and response
Question
dig mail.netorn.net. NS
Answer
The response has no answer records.
Authority
netorn.net. 1790 SOA ns.netorn.ru. admin.netorn.ru. 2025060217 3600 900 3600000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0