smtp.truelink.dk has no NS records.
NS records for this zone are defined at truelink.dk.
NS records for this zone are defined at truelink.dk.
Question and response
Question
dig smtp.truelink.dk. NS
Answer
The response has no answer records.
Authority
truelink.dk. 3600 SOA dns1.cscdns.net. hostmaster.cscdns.net. 2018082354 10800 5400 3600000 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0