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

Results forspf100-5.domaincontrol.com

Resolver

Location

TXT

Name	TTL	Value
spf100-5.domaincontrol.com	600	v=spf1 ip4:68.178.213.0/24 ip4:198.71.224.0/24 ip4:198.71.225.0/24 ip4:198.71.244.0/25 ip4:198.71.245.0/25 ip4:198.71.246.0/25 ip4:198.71.247.0/25 ip4:198.71.253.0/24 ip4:198.71.254.0/24 ip4:198.71.255.0/24 a:spf-a-2.domaincontrol.com -all