mailout01.prod.datev.de has no NS records.
NS records for this zone are defined at prod.datev.de.
NS records for this zone are defined at prod.datev.de.
Question and response
Question
dig mailout01.prod.datev.de. NS
Answer
The response has no answer records.
Authority
prod.datev.de. 600 SOA ns01.datev.de. dnsmaster.datev.de. 2603031051 21600 3600 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0