spf.mailforce.cz has no NS records.
NS records for this zone are defined at mailforce.cz.
NS records for this zone are defined at mailforce.cz.
Question and response
Question
dig spf.mailforce.cz. NS
Answer
The response has no answer records.
Authority
mailforce.cz. 38400 SOA shinzon.blueboard.cz. hostmaster.blueboard.cz. 2018103562 10800 3600 604800 38400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0