mdb4.reg.ru has no NS records.
NS records for this zone are defined at reg.ru.
NS records for this zone are defined at reg.ru.
Question and response
Question
dig mdb4.reg.ru. NS
Answer
The response has no answer records.
Authority
reg.ru. 10800 SOA ns1.reg.ru. hostmaster.ns1.reg.ru. 1772680519 14400 3600 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0