rzdnssecond.rz.tu-bs.de has no NS records.
NS records for this zone are defined at rz.tu-bs.de.
NS records for this zone are defined at rz.tu-bs.de.
Question and response
Question
dig rzdnssecond.rz.tu-bs.de. NS
Answer
The response has no answer records.
Authority
rz.tu-bs.de. 300 SOA rzdnsprime.rz.tu-bs.de. noc.tu-bs.de. 706303530 21600 3600 1814400 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0