mx.postal.k.io has no NS records.
NS records for this zone are defined at postal.k.io.
NS records for this zone are defined at postal.k.io.
Question and response
Question
dig mx.postal.k.io. NS
Answer
The response has no answer records.
Authority
postal.k.io. 3600 SOA prestigious-honeybadger.katapultdns.com. dns-admin.katapult.io. 1771893830 28800 7200 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0