smtp.jsn.de has no NS records.
NS records for this zone are defined at jsn.de.
NS records for this zone are defined at jsn.de.
Question and response
Question
dig smtp.jsn.de. NS
Answer
The response has no answer records.
Authority
jsn.de. 300 SOA x.ns.joker.com. hostmaster.joker.com. 2025121673 14400 3600 1209600 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0