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

Results forthree._spf.proxad.net

Resolver

Location

TXT

Name	TTL	Value
three._spf.proxad.net	86400	v=spf1 ip4:213.36.14.1 ip4:213.36.16.103 ip4:213.36.16.104 ip4:213.36.17.104 ip4:213.36.17.105 ip4:212.27.41.29 ip4:213.36.6.1 ip4:213.36.17.195