ext.helper.otrs.hostcomm.ru has no NS records.
NS records for this zone are defined at otrs.hostcomm.ru.
NS records for this zone are defined at otrs.hostcomm.ru.
Question and response
Question
dig ext.helper.otrs.hostcomm.ru. NS
Answer
The response has no answer records.
Authority
otrs.hostcomm.ru. 600 SOA pdns.infra.nic.ru. noc-dns.nic.ru. 2019121902 14400 3600 2592000 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0