mta.email.dhub.ru has no NS records.
NS records for this zone are defined at dhub.ru.
NS records for this zone are defined at dhub.ru.
Question and response
Question
dig mta.email.dhub.ru. NS
Answer
The response has no answer records.
Authority
dhub.ru. 3600 SOA ns3.dhub.ru. administrator.dhub.ru. 357 900 600 86400 3600
Additional
. 0 OPT ; payload 4000, xrcode 0, version 0, flags 0