A virtualized environment using VirtualBox provides the ability to demonstrate and test many of the configurations and examples outlined in this book. However, there are limitations that inhibit the usefulness of a virtualized environment, such as the use of software virtualization with qemu and the inability of an instance to access remote networks, including the Internet, without network modifications to the underlying host, which are outside the scope of this book. Whenever possible, the use of physical hardware is recommended to ensure a successful experience.