mx1.debeka.de has no NS records.
NS records for this zone are defined at debeka.de.
NS records for this zone are defined at debeka.de.
Question and response
Question
dig mx1.debeka.de. NS
Answer
The response has no answer records.
Authority
debeka.de. 900 SOA dns-dmz-ext2.extranet.debeka.de. hostmaster.debeka.de. 2022052824 10800 3600 2419200 900
Additional
. 0 OPT ; payload 1680, xrcode 0, version 0, flags 0