smtp.admin.grnet.gr has no NS records.
NS records for this zone are defined at admin.grnet.gr.
NS records for this zone are defined at admin.grnet.gr.
Question and response
Question
dig smtp.admin.grnet.gr. NS
Answer
The response has no answer records.
Authority
admin.grnet.gr. 10800 SOA ns0.admin.grnet.gr. administrator.admin.grnet.gr. 2019103015 28800 7200 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0