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

Results forspf.dixa.io

Resolver

Location

TXT

Name	TTL	Value
spf.dixa.io	60	v=spf1 include:amazonses.com ip4:69.169.229.48 ip4:69.169.229.46 ip4:54.240.107.156 ip4:54.240.107.202 ip4:54.240.107.157 ip4:69.169.229.47 ip4:54.240.107.155 ~all