ext.postfix.smedia.tools has no NS records.
NS records for this zone are defined at smedia.tools.
NS records for this zone are defined at smedia.tools.
Question and response
Question
dig ext.postfix.smedia.tools. NS
Answer
The response has no answer records.
Authority
smedia.tools. 60 SOA ns-1.seibert-media-dns.net. root.seibert-media.net. 2016011801 3600 3600 86400 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0