_spf.message-flow.net has no NS records.
NS records for this zone are defined at message-flow.net.
NS records for this zone are defined at message-flow.net.
Question and response
Question
dig _spf.message-flow.net. NS
Answer
The response has no answer records.
Authority
message-flow.net. 1800 SOA athena.ns.cloudflare.com. dns.cloudflare.com. 2398232458 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0