net81.adestra.com has no NS records.
NS records for this zone are defined at adestra.com.
NS records for this zone are defined at adestra.com.
Question and response
Question
dig net81.adestra.com. NS
Answer
The response has no answer records.
Authority
adestra.com. 300 SOA dns-1.adestra.com. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0