_spf.dnsever.com has no NS records.
NS records for this zone are defined at dnsever.com.
NS records for this zone are defined at dnsever.com.
Question and response
Question
dig _spf.dnsever.com. NS
Answer
The response has no answer records.
Authority
dnsever.com. 14400 SOA ns7.dnsever.com. admin.dnsever.com. 1747039760 86400 600 1209600 14400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0