mx.publicsherpa.com has no NS records.
NS records for this zone are defined at publicsherpa.com.
NS records for this zone are defined at publicsherpa.com.
Question and response
Question
dig mx.publicsherpa.com. NS
Answer
The response has no answer records.
Authority
publicsherpa.com. 3600 SOA dns.publicsherpa.com. hostmaster.publicsherpa.com. 1874506334 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0