mars.doreo.com has no NS records.
NS records for this zone are defined at doreo.com.
NS records for this zone are defined at doreo.com.
Question and response
Question
dig mars.doreo.com. NS
Answer
The response has no answer records.
Authority
doreo.com. 300 SOA dns1.name-services.com. info.name-services.com. 1728912323 172800 900 1814400 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0