mx2.sanwell.biz has no NS records.
NS records for this zone are defined at sanwell.biz.
NS records for this zone are defined at sanwell.biz.
Question and response
Question
dig mx2.sanwell.biz. NS
Answer
The response has no answer records.
Authority
sanwell.biz. 38400 SOA NS1.101DOMAIN.COM. ADMIN.sanwell.biz. 2015062752 10800 3600 604800 38400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0