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

Results fora.bna.gr

Resolver

Location

TXT

Name	TTL	Value
a.bna.gr	3600	v=spf1 ip4:37.98.196.202 ip4:65.21.92.243 ip6:2a01:4f9:3b:450c::2 ip4:65.21.92.203 ip6:2a01:4f9:3b:450c::3 ip4:65.21.92.201 ip6:2a01:4f9:3b:450c::5 ip4:65.21.92.202 ip6:2a01:4f9:3b:450c::4 ip4:65.21.92.200 ip6:2a01:4f9:3b:450c::6 -all