mailin.in.tum.de has no NS records.
NS records for this zone are defined at in.tum.de.
NS records for this zone are defined at in.tum.de.
Question and response
Question
dig mailin.in.tum.de. NS
Answer
The response has no answer records.
Authority
in.tum.de. 3600 SOA ns1.rbg.tum.de. postmaster.rbg.tum.de. 1500258079 21600 1800 360000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0