cow.0rbitel.net has no NS records.
NS records for this zone are defined at 0rbitel.net.
NS records for this zone are defined at 0rbitel.net.
Question and response
Question
dig cow.0rbitel.net. NS
Answer
The response has no answer records.
Authority
0rbitel.net. 86400 SOA ns.0rbitel.net. root.orbitel.bg. 2018010401 10800 3600 3600000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0