It can be anything! An apex, subdomain, or even a URL.

Results forspf.xfernet.com

Resolver

Location

TXT

Name	TTL	Value
spf.xfernet.com	300	v=spf1 ip4:67.43.160.0/20 ip4:69.166.0.0/21 ip4:72.34.224.0/19 ip4:208.122.224.0/20 ip4:208.122.237.0/24 ~all