mx.joinsocialgrid.com has no NS records.
NS records for this zone are defined at joinsocialgrid.com.
NS records for this zone are defined at joinsocialgrid.com.
Question and response
Question
dig mx.joinsocialgrid.com. NS
Answer
The response has no answer records.
Authority
joinsocialgrid.com. 3600 SOA dns.joinsocialgrid.com. hostmaster.joinsocialgrid.com. 1537158866 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0