pmail.portunity.de has no NS records.
NS records for this zone are defined at portunity.de.
NS records for this zone are defined at portunity.de.
Question and response
Question
dig pmail.portunity.de. NS
Answer
The response has no answer records.
Authority
portunity.de. 360 SOA ns.portunity.de. hostmaster.portunity.de. 1771368784 10800 3600 3600000 360
Additional
. 0 OPT ; payload 768, xrcode 0, version 0, flags 0