spf2.as23951.net has no CNAME records.
Question and response
Question
dig spf2.as23951.net. NS
Answer
The response has no answer records.
Authority
as23951.net. 253 SOA ns-1720.awsdns-23.co.uk. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0