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

Results forsmtp.emailserver.vn

Resolver

Location

TXT

Name	TTL	Value
smtp.emailserver.vn	300	v=spf1 ip4:112.78.5.0/24 ip4:112.78.6.0/24 ip4:103.15.48.0/24 ip4:125.253.113.0/24 ip4:103.110.129.0/24 ip4:103.110.128.0/24 ip4:125.253.119.0/24 ip4:103.138.88.129/25 -all