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

Results forspf.pantheon.io

Resolver

Location

TXT

Name	TTL	Value
spf.pantheon.io	3600	v=spf1 ip4:50.56.13.72 ip4:104.130.70.5 ip4:192.237.253.9 ip4:23.253.174.11 ip4:23.253.213.4 ip4:23.253.213.7 ip6:2001:4801:7822:103:be76:4eff:fe10:1260 ip6:2001:4801:7824:104:be76:4eff:fe10:13e ip6:2001:4801:7824:104:be76:4eff:fe10:7a2 ip6:2001:4801:7825:104:be76:4eff:fe10:82 ip6:2001:4801:7827:101:be76:4eff:fe10:978 ~all