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

Results forwww3.l.google.com

Resolver

Location

A

Name	TTL	Value
www3.l.google.com	300	2607:f8b0:4004:c09::8aGoogle Public DNS (iad) / Google LLC
www3.l.google.com	300	2607:f8b0:4004:c09::8bGoogle Public DNS (iad) / Google LLC
www3.l.google.com	300	2607:f8b0:4004:c09::65Google Public DNS (iad) / Google LLC
www3.l.google.com	300	2607:f8b0:4004:c09::71Google Public DNS (iad) / Google LLC