Standalone Vagrant environments can meet the needs of a variety of use cases. A common case would be using Vagrant to facilitate web and application development. In this case, forwarding the Vagrant guest web server port (usually port 80) to a port on the localhost would allow applications hosted on the web server to be accessed through a localhost address. (For example, opening http://localhost:8080 in a browser.)
The port forwarding model might not work well for a few use cases. For example:
Situations where a machine must be addressed using a real hostname, either in cases where a web application requires it or when a machine is using SSL certificates.
Modeling deployment environments where different services are installed on dedicated machines. A common example would be developing a web application where a web application is installed and configured on a machine that connects to a database running on a separate virtual machine.
Modeling clustered environments where virtual machines...