smtp.MYNET.JP has no NS records.
NS records for this zone are defined at MYNET.JP.
NS records for this zone are defined at MYNET.JP.
Question and response
Question
dig smtp.MYNET.JP. NS
Answer
The response has no answer records.
Authority
MYNET.JP. 3600 SOA NS21.FreeBit.NET. root.FreeBit.NET. 2019052901 3600 900 604800 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0