a.mx.tornado-mail.com has no NS records.
NS records for this zone are defined at tornado-mail.com.
NS records for this zone are defined at tornado-mail.com.
Question and response
Question
dig a.mx.tornado-mail.com. NS
Answer
The response has no answer records.
Authority
tornado-mail.com. 300 SOA ns.syse.no. hostmaster.syse.no. 1833 10800 1800 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0