This KCNA practice question tests your understanding of kubernetes fundamentals. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 TWO of the following are functions of the kube-controller-manager?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Running the node controller to monitor node health
The kube-controller-manager is a core control plane component that runs controller processes, including the node controller, which monitors node health by checking the NodeStatus and NodeLease objects. If a node becomes unreachable (e.g., the node controller fails to receive a heartbeat within the --node-monitor-grace-period, default 40 seconds), it marks the node as Unhealthy and eventually taints it to trigger pod eviction. This makes option D correct because the node controller is a built-in controller within the kube-controller-manager.
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.
✗
Serving the Kubernetes API
Why it's wrong here
The API is served by kube-apiserver.
✗
Implementing network rules for Services
Why it's wrong here
Network rules and service implementation are handled by kube-proxy on each node.
✗
Scheduling pods to nodes
Why it's wrong here
Pod scheduling is performed by the kube-scheduler, not the controller manager.
✓
Running the node controller to monitor node health
Why this is correct
The node controller periodically checks node status and responds to node failures.
Related concept
Read the scenario before looking for a memorised answer.
✓
Managing ReplicaSets to ensure the desired number of pods are running
Why this is correct
The replication controller (and Deployment controller) ensures the correct number of pod replicas are running.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the distinction between control plane components by listing overlapping responsibilities, so the trap here is confusing the kube-controller-manager's role in managing controllers (like the node controller and ReplicaSet controller) with the kube-scheduler's scheduling function or kube-proxy's network rule implementation.
Detailed technical explanation
How to think about this question
The kube-controller-manager bundles multiple controllers into a single binary, each watching the API server for desired state changes via informers and reconciling the current state. For example, the node controller uses the NodeLifecycleController to manage node taints and lease-based heartbeats (introduced in Kubernetes 1.13), reducing API server load compared to the older pod-status-based approach. In a real-world scenario, if the kube-controller-manager fails, controllers like the ReplicaSet controller (option E) stop reconciling, meaning desired pod counts are not maintained, and node health monitoring ceases, leading to cascading failures.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this KCNA question in full detail.
Kubernetes Fundamentals — This question tests Kubernetes Fundamentals — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Running the node controller to monitor node health — The kube-controller-manager is a core control plane component that runs controller processes, including the node controller, which monitors node health by checking the NodeStatus and NodeLease objects. If a node becomes unreachable (e.g., the node controller fails to receive a heartbeat within the --node-monitor-grace-period, default 40 seconds), it marks the node as Unhealthy and eventually taints it to trigger pod eviction. This makes option D correct because the node controller is a built-in controller within the kube-controller-manager.
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.
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Question Discussion
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