KCNA Container Orchestration Practice Question
Which TWO statements about containers compared to virtual machines are correct? (Select 2)
⚠ Common exam trap
The trap is confusing the isolation and kernel-sharing characteristics of containers and VMs, leading candidates to incorrectly believe VMs share the host kernel or that containers have their own kernel.
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
✓
Containers have lower overhead than virtual machines
Option A is correct because containers do not run a full guest OS or hardware emulation layer; they are just isolated processes on the host kernel, so CPU, memory, and storage overhead is significantly lower than running a hypervisor plus a complete VM. Option B is correct because containers are lightweight by design and share the host operating system kernel through features like namespaces and cgroups, rather than booting their own kernel. Option C is incorrect because virtual machines do not share the host OS kernel; each VM runs its own guest OS and kernel on virtualized hardware. Option D is incorrect because it is containers, not VMs, that share the host kernel; each container does not run its own operating system kernel. Option E is incorrect because VMs generally provide stronger isolation than containers, since the hypervisor separates each VM from the host and from other VMs, whereas containers share the same kernel.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Containers have lower overhead than virtual machines
Why this is correct
Containers share the host kernel rather than virtualising hardware, so each container avoids booting a full guest OS. This eliminates hypervisor and duplicate-kernel overhead, giving faster start-up and denser packing on the same node — directly satisfying the lower-overhead comparison the question asks for.
- ✓
Containers are lightweight and share the host OS kernel
Why this is correct
Containers share the host OS kernel, so each container image excludes a guest operating system, cutting storage and startup overhead. This satisfies the stem's comparison against virtual machines, which each run a full guest OS on the hypervisor. That kernel-sharing architecture is precisely what makes containers lightweight.
- ✗
Virtual machines share the host OS kernel
Why it's wrong here
Virtual machines run their own guest kernel via the hypervisor; the host kernel is not shared. Containers share the host kernel. The statement swaps the two. It is tempting because both abstract hardware, but the hypervisor layer is exactly what gives each VM kernel independence.
- ✗
Each container runs its own operating system kernel
Why it's wrong here
Containers share the host operating system kernel; only virtual machines each run a complete guest kernel. The statement describes virtual machines. It is tempting because containers appear self-contained with their own filesystem and processes, but that userspace packaging sits atop the shared host kernel, not a dedicated one.
- ✗
Virtual machines provide weaker isolation than containers
Why it's wrong here
Containers share the host kernel, so a kernel exploit can cross container boundaries; virtual machines each run a separate kernel with hardware-enforced isolation, giving stronger separation. The statement reverses the relationship. It is tempting because containers feel lightweight and sandboxed, but that lightness is precisely why their isolation boundary is weaker.
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Same concept, more angles
1 more way this is tested on KCNA
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Which TWO statements about containers are true compared to virtual machines? (Select TWO.)
medium- ✓ A.Containers are more lightweight and start faster than VMs
- B.Containers include a full guest operating system
- ✓ C.Containers are more portable across different environments
- D.Containers provide stronger isolation than VMs
- E.Containers require a hypervisor to run
Why A: Containers share the host OS kernel and run as isolated processes, requiring no hypervisor or full OS boot. This makes them lightweight (megabytes vs gigabytes) and allows them to start in milliseconds, whereas VMs must boot a full guest OS, which takes seconds to minutes.
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CNCF exam blueprint
This KCNA practice question is part of Courseiva's free CNCF 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 KCNA exam.