mx.worldsbestshirt.com has no NS records.
NS records for this zone are defined at worldsbestshirt.com.
NS records for this zone are defined at worldsbestshirt.com.
Question and response
Question
dig mx.worldsbestshirt.com. NS
Answer
The response has no answer records.
Authority
worldsbestshirt.com. 3600 SOA dns.worldsbestshirt.com. hostmaster.worldsbestshirt.com. 1527789706 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0