mail.keyweb.de has no NS records.
NS records for this zone are defined at keyweb.de.
NS records for this zone are defined at keyweb.de.
Question and response
Question
dig mail.keyweb.de. NS
Answer
The response has no answer records.
Authority
keyweb.de. 1800 SOA nitin.ns.cloudflare.com. dns.cloudflare.com. 2397001230 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0