CKA Practice Question: Cluster Architecture, Installation and Configuration
Which component is responsible for running containers on a node?
⚠ Common exam trap
It's easy for candidates to confuse the kubelet's role as the node agent with the actual execution of containers, but the kubelet only orchestrates the runtime — it does not run containers itself.
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
✓
container runtime
The container runtime is the software responsible for actually running containers on a node. It pulls container images, creates container namespaces, and manages the container lifecycle (start, stop, delete). In Kubernetes, the kubelet delegates container execution to the container runtime via the CRI (Container Runtime Interface), but the runtime itself performs the low-level operations using technologies like runc or containerd.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
kubelet
Why it's wrong here
The kubelet is the primary node agent that registers nodes, watches pod specs, and reports status back to the control plane. It uses the Container Runtime Interface (CRI) to issue gRPC calls like RunPodSandbox and CreateContainer, but it never directly executes container processes itself. The kubelet is the orchestrator and manager, while the actual process lifecycle is delegated to the configured container runtime.
- ✗
kube-scheduler
Why it's wrong here
The kube-scheduler is a control-plane component responsible only for pod placement decisions. It evaluates unscheduled pods and selects a suitable node based on resource requirements, affinity rules, taints, and tolerations, then writes the binding back to etcd. Once a pod is bound to a node, the scheduler's job is complete; it has no mechanism to launch or manage containers on any node, so it cannot be the component that runs containers.
- ✓
container runtime
Why this is correct
The container runtime is the low-level software that actually runs containers on a node. It implements the Kubernetes CRI (e.g., containerd, CRI-O) and uses an OCI-compliant runtime like runc to create namespaces, set up cgroups, and execute container processes as the kernel sees them. When the kubelet requests a pod sandbox or container, the runtime pulls images, mounts filesystems, and starts the user process — making it the direct executor of container workloads.
- ✗
kube-proxy
Why it's wrong here
kube-proxy is a node-level network proxy that implements Kubernetes Service abstractions by managing iptables, IPVS, or eBPF rules. Its sole purpose is to handle load balancing and traffic forwarding to pod endpoints, along with some service discovery tasks. It never interacts with container processes directly and has no role in creating or managing containers, so it is entirely unrelated to the function of running containers on a node.
Go deeper
Related to this question
Learn chapter
Kubernetes Architecture Overview
Key term
Network Policies
A Kubernetes resource that controls how pods communicate with each other and with other network endpoints, acting as a firewall for pod-to-pod traffic.
Key term
Container Runtime
A container runtime is software that runs containers by using the host operating system's kernel to isolate processes, manage filesystem layers, and handle networking.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CKA 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 CKA exam.