mail.domru.ru has no NS records.
NS records for this zone are defined at domru.ru.
NS records for this zone are defined at domru.ru.
Question and response
Question
dig mail.domru.ru. NS
Answer
The response has no answer records.
Authority
domru.ru. 3600 SOA ns6.ertelecom.ru. noc.ertelecom.ru. 2026022701 86400 1800 604800 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0