exchange.thenap.com has no NS records.
NS records for this zone are defined at thenap.com.
NS records for this zone are defined at thenap.com.
Question and response
Question
dig exchange.thenap.com. NS
Answer
The response has no answer records.
Authority
thenap.com. 300 SOA ns1-02.azure-dns.com. azuredns-hostmaster.microsoft.com. 1 3600 300 2419200 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0