mx02.bwh.nu has no NS records.
NS records for this zone are defined at bwh.nu.
NS records for this zone are defined at bwh.nu.
Question and response
Question
dig mx02.bwh.nu. NS
Answer
The response has no answer records.
Authority
bwh.nu. 1800 SOA lisa.ns.cloudflare.com. dns.cloudflare.com. 2397086558 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0