spf.runbox.com has no NS records.
NS records for this zone are defined at runbox.com.
NS records for this zone are defined at runbox.com.
Question and response
Question
dig spf.runbox.com. NS
Answer
The response has no answer records.
Authority
runbox.com. 3600 SOA dns61.copyleft.no. hostmaster.copyleft.no. 3000010758 14400 3600 1296000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0