dtexternal.pt.lu has no NS records.
NS records for this zone are defined at pt.lu.
NS records for this zone are defined at pt.lu.
Question and response
Question
dig dtexternal.pt.lu. NS
Answer
The response has no answer records.
Authority
pt.lu. 600 SOA ns1.pt.lu. hostmaster.ns1.pt.lu. 2026021800 10800 3600 2419200 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0