mx.bobvox.com has no NS records.
NS records for this zone are defined at bobvox.com.
NS records for this zone are defined at bobvox.com.
Question and response
Question
dig mx.bobvox.com. NS
Answer
The response has no answer records.
Authority
bobvox.com. 3600 SOA dns.bobvox.com. hostmaster.bobvox.com. 1730823295 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0