spf1.supportbox.cz has no NS records.
NS records for this zone are defined at supportbox.cz.
NS records for this zone are defined at supportbox.cz.
Question and response
Question
dig spf1.supportbox.cz. NS
Answer
The response has no answer records.
Authority
supportbox.cz. 1800 SOA darwin.ns.cloudflare.com. dns.cloudflare.com. 2397943238 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0