- A
rkt
Why wrong: rkt (pronounced 'rocket') is a container runtime that does not implement the CRI and is not commonly used in Kubernetes.
- B
containerd
containerd is a CRI-compliant runtime and is widely used in Kubernetes.
- C
Kata Containers
Kata Containers provides strong isolation using lightweight VMs and implements the CRI.
- D
Docker
Why wrong: Docker does not implement the CRI natively; it was supported via dockershim, which was removed in Kubernetes v1.24.
- E
CRI-O
CRI-O is specifically built for Kubernetes and implements the CRI.
Question 432 of 997
CRI Runtimes: containerd, CRI-O, Kata Containers
This KCNA practice question tests your understanding of container orchestration. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which THREE of the following are valid container runtimes that can be used with Kubernetes via the Container Runtime Interface (CRI)? (Select three.)
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
✓
containerd
B is correct because containerd is a core container runtime that implements the CRI (Container Runtime Interface) directly via its built-in CRI plugin. It was extracted from Docker and is now the default runtime in many Kubernetes distributions, handling image management, container lifecycle, and execution without requiring an external shim.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
rkt
Why it's wrong here
rkt (pronounced 'rocket') is a container runtime that does not implement the CRI and is not commonly used in Kubernetes.
- ✓
containerd
Why this is correct
containerd is a CRI-compliant runtime and is widely used in Kubernetes.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
Kata Containers
Why this is correct
Kata Containers provides strong isolation using lightweight VMs and implements the CRI.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Docker
Why it's wrong here
Docker does not implement the CRI natively; it was supported via dockershim, which was removed in Kubernetes v1.24.
- ✓
CRI-O
Why this is correct
CRI-O is specifically built for Kubernetes and implements the CRI.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Kubernetes often tests the misconception that Docker is a valid CRI-compliant runtime, but the trap is that Docker uses containerd under the hood and was removed from Kubernetes as a direct runtime after v1.24, so candidates must recognize that only runtimes with native CRI implementations (like containerd, CRI-O, and Kata Containers) are valid.
Detailed technical explanation
How to think about this question
The CRI defines a gRPC protocol (kubelet <-> runtime) with two services: RuntimeService (for pods/containers) and ImageService (for images). containerd implements these via its CRI plugin (cri-containerd), while CRI-O is a lightweight runtime built specifically for CRI compliance. Kata Containers uses a hypervisor-based isolation layer (KVM/QEMU) and integrates with CRI via the containerd-shim-kata-v2 or CRI-O runtime handler, providing hardware-level security boundaries.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the KCNA exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
- →
Container Orchestration — study guide chapter
Learn the concepts, then practise the questions
- →
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Targeted practice on this topic area only
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FAQ
Questions learners often ask
What does this KCNA question test?
Container Orchestration — This question tests Container Orchestration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: containerd — B is correct because containerd is a core container runtime that implements the CRI (Container Runtime Interface) directly via its built-in CRI plugin. It was extracted from Docker and is now the default runtime in many Kubernetes distributions, handling image management, container lifecycle, and execution without requiring an external shim.
What should I do if I get this KCNA question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
4 more ways 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 of the following are container runtimes that implement the Container Runtime Interface (CRI)? (Choose two.)
medium- A.Docker
- ✓ B.containerd
- C.Podman
- ✓ D.CRI-O
- E.runc
Why B: containerd is a core container runtime that implements the Container Runtime Interface (CRI), which is the Kubernetes API for integrating container runtimes. It was originally extracted from Docker and is now a graduated CNCF project, providing a stable CRI-compatible interface for managing container lifecycles.
Variation 2. Which of the following is a container runtime that implements the Container Runtime Interface (CRI)?
easy- ✓ A.containerd
- B.Docker
- C.runc
- D.kubelet
Why A: containerd is a high-level container runtime that directly implements the Container Runtime Interface (CRI) by exposing a gRPC API that kubelet can call to manage pods and containers. It was originally extracted from Docker and is now the default runtime in many Kubernetes distributions, providing image transfer, container lifecycle management, and storage/network attachment without requiring Docker as an intermediary.
Variation 3. Which of the following is a container runtime that implements the Container Runtime Interface (CRI)?
medium- A.rkt
- B.Docker
- ✓ C.containerd
- D.Hyper-V
Why C: containerd is correct because it is a high-level container runtime that directly implements the Container Runtime Interface (CRI) defined by Kubernetes. It was designed to be a lightweight, core container runtime that can manage the full lifecycle of containers (create, start, stop, delete) and expose these operations via the CRI gRPC API, making it a drop-in replacement for Docker in Kubernetes clusters.
Variation 4. Which THREE are valid container runtimes that implement the Kubernetes CRI? (Choose three.)
hard- ✓ A.Docker (via dockershim, deprecated)
- ✓ B.containerd
- C.runc
- ✓ D.CRI-O
- E.rkt
Why A: containerd, CRI-O, and Docker (via dockershim, deprecated) implement CRI. rkt is discontinued and not CRI-compliant; runc is a low-level runtime, not a CRI implementation.
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Last reviewed: Jul 4, 2026
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.
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