There are two types of hypervisors: type 1 and type 2 hypervisor. In type 1 hypervisor (or native hypervisor), the hypervisor is installed directly on the physical server. Then instances of an operating system (OS) are installed on the hypervisor. Type 1 hypervisor has direct access to the hardware resources. Therefore they are more efficient than hosted architectures. Some examples of type 1 hypervisor are VMware vSphere/ESXi, Oracle VM Server, KVM and Microsoft Hyper-V.
In contrast to type 1 hypervisor, a type 2 hypervisor (or hosted hypervisor) runs on top of an operating system and not the physical hardware directly. A big advantage of Type 2 hypervisors is that management console software is not required. Examples of type 2 hypervisor are VMware Workstation (which can run on Windows, Mac and Linux) or Microsoft Virtual PC (only runs on Windows).
Type 1 is more efficient and well performing, it is also more secure than type 2 because the flaws and vulnerabilities that are endemic to Operating Systems are often absent from Type 1, bare metal hypervisors. Type 1 has better performance, scalability and stability but supported by limited hardware.

The 204 (No Content) status code indicates that the server has successfully fulfilled the request and that there is no additional content to send in the response payload body. Metadata in the response header fields refer to the target resource and its selected representation after the requested action was applied.

Separation of Privilege: Granting permissions to an entity should not be purely based on a single condition, a combination of conditions based on the type of resource is a better idea.