Courseiva
← KCNA
Full test
Container Orchestration →mediumMultiple Select

KCNA Container Orchestration Practice Question

Which TWO of the following are valid container runtimes that implement the CRI? (Choose two.)

⚠ Common exam trap

CNCF often tests the misconception that Docker is a CRI-compliant runtime because it was historically the default container runtime in Kubernetes, but candidates must remember that Docker uses its own API and was only supported via the now-removed dockershim, making containerd and CRI-O the only correct CRI implementations among the options.

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

✓

CRI-O

CRI-O (option B) is a lightweight container runtime purpose-built by Red Hat specifically to implement the Kubernetes Container Runtime Interface (CRI), so it directly satisfies the requirement. containerd (option D) also natively implements the CRI plugin, which is why Kubernetes can use it as a container runtime without any additional shim. Kata Containers (option A) is a runtime that provides VM-isolated containers but is typically plugged in via a CRI implementation such as containerd's CRI plugin or CRI-O, not as a standalone CRI runtime itself. Docker (option C) predates the CRI and does not implement it natively; it required the deprecated dockershim adapter to work with Kubernetes. rkt (option E) was an alternative container runtime that never implemented the CRI and has since been discontinued.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • ✗

    Kata Containers

    Why it's wrong here

    Kata Containers is a runtime providing VM-isolated sandboxes via virtcontainers, not a CRI implementation itself; it sits beneath a CRI shim such as containerd. It is tempting because Kata is a legitimate OCI-compliant runtime, correct when the question asks about isolation mechanisms rather than CRI conformance.

  • ✓

    CRI-O

    Why this is correct

    CRI-O is purpose-built to implement the Kubernetes Container Runtime Interface, exposing only the gRPC CRI API rather than a broader runtime surface. This satisfies the stem's requirement for a valid CRI-implementing runtime, letting kubelet manage containers without Docker or containerd shims.

  • ✗

    Docker

    Why it's wrong here

    Docker predates the CRI and was removed from Kubernetes as a runtime; dockershim was deprecated because Docker's API does not implement CRI directly, requiring a shim. It is tempting because Docker remains the familiar container toolchain, and it would be valid if the question asked about image-building or local development rather than CRI-compliant runtimes.

  • ✓

    containerd

    Why this is correct

    containerd implements the Kubernetes Container Runtime Interface natively, exposing the required gRPC services for kubelet to manage pods and containers. It satisfies the CRI constraint directly, unlike Docker, which required the deprecated dockershim adapter. This makes containerd a valid CRI-compliant runtime.

  • ✗

    rkt

    Why it's wrong here

    rkt is not commonly used and does not implement CRI.

About these practice questions

This KCNA question is part of Courseiva's 930-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →

How Courseiva writes practice questions · Editorial policy

JA

Written by Johnson Ajibi, MSc IT Security

Senior Network & Security Engineer · founder of Courseiva

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.