VCP-DCV vSphere Performance and Scaling Practice Question
A vSphere administrator notices high memory ballooning on a host running multiple VMs with large memory allocations. The host has sufficient physical memory, but ballooning occurs sporadically. What is the most likely cause?
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
✓
The VM's memory limit is set too low
The VM's memory limit is set too low. Memory ballooning occurs when the ESXi host reclaims memory from a VM by instructing the guest OS to release memory via the balloon driver. If a VM's memory limit is set lower than its allocated memory, the hypervisor will enforce that limit even if the host has free physical memory. This can cause sporadic ballooning as the VM's memory usage approaches the limit. Option A is incorrect because CPU overcommitment does not directly cause memory ballooning; ballooning is a memory reclamation technique. Option C is incorrect because if memory reservation exceeds physical memory, the VM cannot power on at all; it does not cause ballooning. Option D is incorrect because insufficient swap space would lead to swapping or memory allocation failures, not ballooning; ballooning is a proactive driver-based mechanism.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The host is overcommitted on CPU
Why it's wrong here
CPU overcommitment causes CPU ready time, not memory ballooning.
- ✓
The VM's memory limit is set too low
Why this is correct
A memory limit below the VM's active memory forces the balloon driver to reclaim memory from the guest, even if host has free memory.
- ✗
The VM's memory is set to a reservation higher than the physical memory
Why it's wrong here
A reservation higher than available physical memory prevents the VM from powering on.
- ✗
The host has insufficient swap space
Why it's wrong here
Insufficient swap space can cause swapping failures, but ballooning is a proactive reclamation method independent of swap space.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This VCP-DCV practice question is part of Courseiva's free VMware certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the VCP-DCV exam.