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

Results forspf.esosoft.net

Resolver

Location

TXT

Name	TTL	Value
spf.esosoft.net	3600	v=spf1 ip4:66.241.145.0/24 ip4:66.241.144.0/24 ip6:2607:f7c8:1::/64 ip4:208.111.40.61/32 ip6:2607:f7c8:1::/64 ip4:176.58.88.69/32 ip4:199.38.181.40/32 ip4:66.241.159.0/24 include:spf.antispamcloud.com -all