spf1.ppepost.net has no NS records.
NS records for this zone are defined at ppepost.net.
NS records for this zone are defined at ppepost.net.
Question and response
Question
dig spf1.ppepost.net. NS
Answer
The response has no answer records.
Authority
ppepost.net. 900 SOA ns-1135.awsdns-13.org. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0