spf.smtp.hu has no NS records.
NS records for this zone are defined at smtp.hu.
NS records for this zone are defined at smtp.hu.
Question and response
Question
dig spf.smtp.hu. NS
Answer
The response has no answer records.
Authority
smtp.hu. 300 SOA ns1.vhost.hu. hostmaster.vhost.hu. 1758026872 3600 7200 604800 300
Additional
. 0 OPT ; payload 1680, xrcode 0, version 0, flags 0