CompTIA Cloud+ Practice Test

What is the term for a hypervisor function that reclaims unused memory from a virtual machine?

1. Memory Throttling

2. Memory Allocation

3. Memory Ballooning

4. Memory Sharing

The correct answer is: Memory Ballooning

The appropriate term for the hypervisor function that reclaims unused memory from a virtual machine is memory ballooning. This technique allows the hypervisor to manage and optimize memory use among virtual machines on a host. When a virtual machine has excess allocated memory that isn't being utilized, the ballooning process enables the hypervisor to 'inflate' a special driver within the VM, effectively claiming the unused memory back to the host system. This process is particularly useful in environments with limited physical memory, allowing for better resource allocation among multiple VMs. By reclaiming this memory, the hypervisor can redistribute it to other virtual machines that may require more resources, thereby ensuring more efficient overall system performance. Memory ballooning is a dynamic method allowing the hypervisor to adjust memory resources as workload changes, making it a fundamental feature in virtualized environments. Other terms such as memory throttling, memory allocation, and memory sharing pertain to different memory management concepts and do not specifically refer to the reclamation of unused memory, which is the essence of ballooning. Memory throttling involves limiting the memory usage of a VM, memory allocation focuses on assigning memory resources initially, and memory sharing relates to the ability of multiple VMs to share memory pages to reduce the overall memory footprint.