220-1101 Virtualization and Cloud Computing Practice Question
A company uses a hypervisor to run multiple virtual machines on a single physical server. The host server has 64 GB of RAM. The administrator allocates 8 GB of RAM to each of 10 VMs, for a total allocation of 80 GB. The hypervisor utilizes memory overcommitment, which allows the total allocated memory to exceed the physical memory by sharing idle memory pages among VMs. Which of the following cloud computing characteristics does this configuration BEST demonstrate?
⚠ Common exam trap
Test-takers frequently confuse resource pooling with rapid elasticity because both involve dynamic resource allocation, but resource pooling focuses on the abstraction and sharing of a static pool, while elasticity is about scaling the pool itself in response to demand.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Resource pooling
Resource pooling is the cloud characteristic demonstrated because the hypervisor aggregates the physical memory (64 GB) into a shared pool and dynamically allocates it to multiple VMs as needed, even though the total allocated memory (80 GB) exceeds the physical capacity. Memory overcommitment relies on the hypervisor's ability to reclaim idle pages from one VM and assign them to another, which is a direct implementation of resource pooling where physical resources are abstracted and shared among tenants.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
On-demand self-service
Why it's wrong here
On-demand self-service is the cloud characteristic that lets users provision services and compute capabilities automatically, without requiring a service provider's manual intervention. It governs the initiation and delivery of IT resources on request. It does not describe the hypervisor's memory sharing technique, because memory overcommitment is an internal resource management method, not a user-facing provisioning feature.
- ✗
Rapid elasticity
Why it's wrong here
Rapid elasticity enables cloud resources to scale outward and inward automatically, making capabilities appear unlimited and aligned with current demand. This dynamic scaling adjusts to workload spikes or drops in near real-time. Memory overcommitment, however, is not a scaling behavior; it is a static capacity optimization where the hypervisor allocates more virtual memory than physical RAM, relying on the fact that VMs rarely consume their full allocation simultaneously.
- ✓
Resource pooling
Why this is correct
Resource pooling is the correct characteristic because it directly describes how a hypervisor aggregates physical memory and provisions it dynamically across multiple VMs. Memory overcommitment is a prime example: the hypervisor assigns each VM a set amount of virtual RAM from the shared physical pool, overcommitting so that the sum of allocations exceeds available physical memory. This pooling of resources maximizes utilization and allows more VMs per host than dedicated allocation would permit.
- ✗
Measured service
Why it's wrong here
Measured service refers to the cloud system's ability to monitor, control, and report resource usage for billing and optimization purposes. It provides metering data such as memory consumption, CPU usage, or network bandwidth, enabling pay-per-use pricing. It is not the mechanism for sharing or overcommitting memory; rather, it is an oversight layer that tracks the effects of resource pooling after the fact.
Go deeper
Related to this question
Learn chapter
Network Configuration: IP, DNS, DHCP
Key term
Dual In-line Memory Module
A Dual In-line Memory Module (DIMM) is a small circuit board that holds memory chips and plugs into a computer's motherboard to provide Random Access Memory (RAM).
Key term
Software as a Service
Software as a Service (SaaS) is a cloud computing model where users access software applications over the internet on a subscription basis, without installing or maintaining the software locally.
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