Every cf push deploys applications to one particular Cloud Foundry instance. Every Cloud Foundry instance may have a shared domain set by an admin. Unless you specify a domain, Cloud Foundry incorporates that shared domain in the route to your application.

You can use the domain attribute when you want your application to be served from a domain other than the default shared domain.

---
  ...
  domain: unique-example.com

The command line option that overrides this attribute is -d.

The domains attribute

Use the domains attribute to provide multiple domains. If you define both domain and domains attributes, Cloud Foundry creates routes for domains defined in both of these fields.

---
  ...
  domains:
  - domain-example1.com
  - domain-example2.org

The command line option that overrides this attribute is -d.