mail.sdn.spb.ru has no NS records.
NS records for this zone are defined at sdn.spb.ru.
NS records for this zone are defined at sdn.spb.ru.
Question and response
Question
dig mail.sdn.spb.ru. NS
Answer
The response has no answer records.
Authority
sdn.spb.ru. 86400 SOA ns-01.stackdata.net. hostmaster.stackdata.net. 2025032601 28800 7200 604800 86400
Additional
. 0 OPT ; payload 1680, xrcode 0, version 0, flags 0