mail.renrest.ru has no NS records.
NS records for this zone are defined at renrest.ru.
NS records for this zone are defined at renrest.ru.
Question and response
Question
dig mail.renrest.ru. NS
Answer
The response has no answer records.
Authority
renrest.ru. 10800 SOA ns1.reg.ru. hostmaster.ns1.reg.ru. 1759328272 14400 3600 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0