This is a Cloud Foundry CLI plugin to find the application a given hostname/domain/route is bound to. Note this will only show applications in orgs/spaces that the logged-in user has permissions to view.
$ cf lookup-route <my.example.com>
Bound to:
<org>/<space>/<app>
# use -t to target the org/space containing the route
$ cf lookup-route -t <my.example.com>
Bound to:
<org>/<space>/<app>
Changed target to: <org>/<space>
$ cf lookup-route <unknown.example.com>
Error retrieving apps: Route not found.