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

Results for_spf.eemsg2.mail.mil

Resolver

Location

TXT

Name	TTL	Value
_spf.eemsg2.mail.mil	1866	spf2.0/pra ip4:214.24.21.225/29 ip4:214.24.22.225/29 ip4:214.24.24.225/29 ip4:214.24.26.225/29 ip4:214.24.27.225/29 -all
_spf.eemsg2.mail.mil	1866	v=spf1 ip4:214.24.21.225/29 ip4:214.24.22.225/29 ip4:214.24.24.225/29 ip4:214.24.26.225/29 ip4:214.24.27.225/29 -all