mx-second.donpac.ru has no NS records.
NS records for this zone are defined at donpac.ru.
NS records for this zone are defined at donpac.ru.
Question and response
Question
dig second.mx.donpac.ru. NS
Answer
The response has no answer records.
Authority
donpac.ru. 3600 SOA ns0.donpac.ru. dnsmaster.donpac.ru. 2025090401 43200 7200 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0