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

Results fornets2.spf.messagelabs.com

Resolver

Location

TXT

Name	TTL	Value
nets2.spf.messagelabs.com	3600	v=spf1 ip4:216.82.240.0/20 ip4:67.219.240.0/20 ip4:117.120.16.0/21 ip4:103.9.96.0/22 ip4:35.228.216.85 ip4:146.148.116.76 ip4:34.141.160.224 ip4:34.70.158.162 ip4:34.74.74.140 ip4:34.83.159.189