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

Results forspf3.casefox.com

Resolver

Location

TXT

Name	TTL	Value
spf3.casefox.com	600	v=spf1 ip4:204.220.176.0/20 ip4:141.193.32.0/23 ip4:159.135.140.80/29 ip4:159.135.132.128/25 ip4:87.253.232.0/21 ip4:185.189.236.0/22 ip4:185.211.120.0/22 ip4:185.250.236.0/22 ip4:143.55.236.0/22 ip4:204.220.160.0/21 include:spf4.casefox.com ~all