What does a virtual machine do?

A virtual machine simulates a computer within another computer by using software to mimic the hardware functionality, allowing multiple operating systems to run on a single physical machine. This is accomplished through a hypervisor, which allocates resources such as CPU, memory, and storage from the host system to the virtual machine, enabling it to operate as if it were a standalone physical computer.

The capability of running multiple virtual machines on a single host machine leads to more efficient use of hardware resources, flexibility in testing environments, and isolation between different operating systems or applications. This virtualized setup is ideal for developers and testers who need to create varied environments without the need for multiple physical machines.

While the other options touch on aspects related to virtualization, they do not accurately describe the primary function of a virtual machine. For instance, copying physical hardware does not reflect the purpose of a virtual machine, which involves emulation rather than duplication. Replacing physical servers may happen as a result of virtualization technology, but it is not an inherent function of a virtual machine itself. Enhancing network performance is more related to specific network configurations and optimizations than to the concept of virtual machines.