mx.frockcloud.com has no NS records.
NS records for this zone are defined at frockcloud.com.
NS records for this zone are defined at frockcloud.com.
Question and response
Question
dig mx.frockcloud.com. NS
Answer
The response has no answer records.
Authority
frockcloud.com. 3600 SOA dns.frockcloud.com. hostmaster.frockcloud.com. 1635579750 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0