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

Results forspf2.serverdomain.org

Resolver

Location

TXT

Name	TTL	Value
spf2.serverdomain.org	3600	v=spf1 ip4:116.202.6.18 ip4:157.90.250.215 ip4:78.47.92.237 ip4:78.47.57.246 ip4:88.99.124.251 ip4:159.69.101.130 ip4:168.119.242.81 ip6:2a01:50c0::/32 -all