mail.sv-en.ru has no NS records.
NS records for this zone are defined at sv-en.ru.
NS records for this zone are defined at sv-en.ru.
Question and response
Question
dig mail.sv-en.ru. NS
Answer
The response has no answer records.
Authority
sv-en.ru. 259200 SOA ns1.sv-en.ru. hostmaster.sv-en.ru. 2026031802 86400 7200 2592000 345600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0