mta5.expertsender.ru has no NS records.
NS records for this zone are defined at expertsender.ru.
NS records for this zone are defined at expertsender.ru.
Question and response
Question
dig mta5.expertsender.ru. NS
Answer
The response has no answer records.
Authority
expertsender.ru. 300 SOA ns1-01.azure-dns.com. azuredns-hostmaster.microsoft.com. 1 3600 300 2419200 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0