mx.preowned-cars.com has no NS records.
NS records for this zone are defined at preowned-cars.com.
NS records for this zone are defined at preowned-cars.com.
Question and response
Question
dig mx.preowned-cars.com. NS
Answer
The response has no answer records.
Authority
preowned-cars.com. 3600 SOA dns.preowned-cars.com. hostmaster.preowned-cars.com. 1259785278 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0