_spf.s7host.net has no CNAME records.
Question and response
Question
dig _spf.s7host.net. NS
Answer
The response has no answer records.
Authority
s7host.net. 3600 SOA ns1.s7host.net. admin.sencia.ca. 2026010101 900 600 43200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0