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

Results forspf21.mailgrid.net.br

Resolver

Location

TXT

Name	TTL	Value
spf21.mailgrid.net.br	300	v=spf1 ip4:158.69.195.121 ip4:51.79.38.67 ip4:54.39.164.153 ip4:192.99.254.115 ip4:192.99.83.140 ip4:51.79.44.80 ip4:66.70.156.191 ip4:158.69.5.44 ip4:158.69.187.247 ip4:167.114.34.3 ip4:54.39.14.88 ip4:51.79.38.68 ip4:51.79.38.69 -all