mx6.basmail.jp has no NS records.
NS records for this zone are defined at basmail.jp.
NS records for this zone are defined at basmail.jp.
Question and response
Question
dig mx6.basmail.jp. NS
Answer
The response has no answer records.
Authority
basmail.jp. 600 SOA dns0.tokai.or.jp. postmaster.tokai.or.jp. 20250901 3600 300 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0