spf.contabo.com has no NS records.
NS records for this zone are defined at contabo.com.
NS records for this zone are defined at contabo.com.
Question and response
Question
dig spf.contabo.com. NS
Answer
The response has no answer records.
Authority
contabo.com. 1800 SOA ben.ns.cloudflare.com. dns.cloudflare.com. 2396786938 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0