roob.abtionb.com has no NS records.
NS records for this zone are defined at abtionb.com.
NS records for this zone are defined at abtionb.com.
Question and response
Question
dig roob.abtionb.com. NS
Answer
The response has no answer records.
Authority
abtionb.com. 3601 SOA dns1.registrar-servers.com. hostmaster.registrar-servers.com. 1773249231 43200 3600 604800 3601
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0