mail.voztelecom.net has no CNAME records.
Question and response
Question
dig mail.voztelecom.net. NS
Answer
The response has no answer records.
Authority
voztelecom.net. 5836 SOA ns1.voztelecom.net. root.voztelecom.net. 2026022501 21600 3600 691200 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0