Question 558 of 997

Kubernetes Fundamentals →mediumMultiple ChoiceObjective-mapped

Pod Pending — Insufficient CPU Resources

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.

A pod is stuck in 'Pending' state. After running 'kubectl describe pod', you see the event: '0/3 nodes are available: 3 Insufficient cpu'. What is the most likely cause?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

A
The pod's CPU request exceeds the available CPU on all nodes
The scheduler reports insufficient CPU resources.
B
The pod is exceeding its memory limit
Why wrong: Memory issues cause OOMKilled, not pending.
C
The network plugin is not installed
Why wrong: Network plugin issues cause different errors (e.g., CrashLoopBackOff).
D
The container image is too large
Why wrong: Image size does not cause CPU insufficiency.

Full breakdown with real-world context →

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

✓

The pod's CPU request exceeds the available CPU on all nodes

The pod is stuck in 'Pending' state because the Kubernetes scheduler cannot find a node that satisfies the pod's resource requirements. The event '0/3 nodes are available: 3 Insufficient cpu' explicitly indicates that every node in the cluster lacks sufficient allocatable CPU capacity to meet the pod's CPU request. This means the sum of CPU requests across all pods on each node, plus the new pod's request, exceeds the node's CPU capacity, causing the scheduler to leave the pod unscheduled.

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.

✓
The pod's CPU request exceeds the available CPU on all nodes
Why this is correct
The scheduler reports insufficient CPU resources.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The pod is exceeding its memory limit
Why it's wrong here
Memory issues cause OOMKilled, not pending.
✗
The network plugin is not installed
Why it's wrong here
Network plugin issues cause different errors (e.g., CrashLoopBackOff).
✗
The container image is too large
Why it's wrong here
Image size does not cause CPU insufficiency.

Common exam traps

Common exam trap: answer the scenario, not the keyword

A common mistake in Kubernetes is confusing resource requests (used for scheduling) with resource limits (used for runtime enforcement). Candidates may incorrectly think a pod stuck in 'Pending' is due to exceeding a limit rather than an unsatisfied request.

Detailed technical explanation

How to think about this question

The Kubernetes scheduler uses a predicate (filtering) phase where it checks each node's allocatable resources against the pod's resource requests (not limits). The 'Insufficient cpu' message means the node's 'capacity - sum(requests of existing pods) - (system-reserved + kube-reserved)' is less than the pod's CPU request. This can happen even if nodes have free CPU in terms of actual usage, because scheduling is based on requests, not real-time utilization — a common source of confusion in capacity planning.

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.

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FAQ

Questions learners often ask

What does this KCNA question test?

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: The pod's CPU request exceeds the available CPU on all nodes — The pod is stuck in 'Pending' state because the Kubernetes scheduler cannot find a node that satisfies the pod's resource requirements. The event '0/3 nodes are available: 3 Insufficient cpu' explicitly indicates that every node in the cluster lacks sufficient allocatable CPU capacity to meet the pod's CPU request. This means the sum of CPU requests across all pods on each node, plus the new pod's request, exceeds the node's CPU capacity, causing the scheduler to leave the pod unscheduled.

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.

Are there clue words in this question I should notice?

Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

About these practice questions

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Same concept, more angles

1 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. A Pod has been in 'Pending' state for an unusual amount of time. Which of the following is a likely cause?

medium

A.The container image is invalid
B.The Pod's liveness probe is failing
✓ C.The cluster does not have enough resources to schedule the Pod
D.The Service pointing to the Pod is misconfigured

Why C: A Pod stuck in 'Pending' state indicates that the Pod has been accepted by the API server but has not been scheduled to a node. The most common cause is insufficient cluster resources (CPU, memory, or ephemeral storage) across all nodes, preventing the scheduler from finding a suitable node that meets the Pod's resource requests. The scheduler continuously evaluates nodes using predicates and priorities, and if no node passes the predicates (e.g., NodeResourcesFit), the Pod remains Pending.

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Question Discussion

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