mx.vtmail.ru has no NS records.
NS records for this zone are defined at vtmail.ru.
NS records for this zone are defined at vtmail.ru.
Question and response
Question
dig mx.vtmail.ru. NS
Answer
The response has no answer records.
Authority
vtmail.ru. 86400 SOA ns.mts-nn.ru. hostmaster.mts-nn.ru. 2020102701 10800 3600 1500000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0