mail.virt.ja.net has no NS records.
NS records for this zone are defined at virt.ja.net.
NS records for this zone are defined at virt.ja.net.
Question and response
Question
dig mail.virt.ja.net. NS
Answer
The response has no answer records.
Authority
virt.ja.net. 60 SOA sdc-ipam-001.inf.virt.ja.net. netman.virt.ja.net. 4143 7200 1800 2419200 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0