- A
The Deployment's resource requests exceed node capacity
Why wrong: If resources were insufficient, pods would be pending, not running but unavailable.
- B
The Service selector does not match the pod labels
Why wrong: Service selector does not affect the Deployment's available count.
- C
The pods have a failing readiness probe
A failing readiness probe prevents the pod from being marked as available, while the pod itself is running.
- D
The kubelet on one node is not functioning
Why wrong: If a kubelet were down, the pod would be in an unknown state, not running but unavailable.
Question 856 of 997
Readiness Probe — Why Deployment Pods Are Not Available
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 Deployment named 'web-app' has been running with 3 replicas. After a configuration change, you notice that only 2 pods are ready. You run 'kubectl describe deployment web-app' and see 'Replicas: 3 desired | 3 total | 3 up-to-date | 2 available'. 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.
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 pods have a failing readiness probe
The key detail is that 3 pods are desired, 3 are up-to-date, but only 2 are available. This indicates the pods are running but not passing their readiness probes, so they are not included in the Service's endpoints. A failing readiness probe prevents traffic from being routed to a pod, even if it is otherwise healthy, which matches the symptom of fewer available pods than desired.
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 Deployment's resource requests exceed node capacity
Why it's wrong here
If resources were insufficient, pods would be pending, not running but unavailable.
- ✗
The Service selector does not match the pod labels
Why it's wrong here
Service selector does not affect the Deployment's available count.
- ✓
The pods have a failing readiness probe
Why this is correct
A failing readiness probe prevents the pod from being marked as available, while the pod itself is running.
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 kubelet on one node is not functioning
Why it's wrong here
If a kubelet were down, the pod would be in an unknown state, not running but unavailable.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The CNCF exam often tests the distinction between 'available' (ready and serving traffic) and 'up-to-date' (matching the latest spec) to trap candidates who confuse pod running status with readiness.
Detailed technical explanation
How to think about this question
Readiness probes are defined in the pod spec under `spec.containers[].readinessProbe` and can use HTTP GET, TCP socket, or exec commands. The kubelet executes the probe periodically; if it fails, the pod's `Ready` condition is set to False, and the pod is removed from the Endpoints object backing the Service. This is distinct from liveness probes, which restart the pod on failure — readiness probes only affect traffic routing, not pod lifecycle.
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.
- →
Kubernetes Fundamentals — 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?
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 pods have a failing readiness probe — The key detail is that 3 pods are desired, 3 are up-to-date, but only 2 are available. This indicates the pods are running but not passing their readiness probes, so they are not included in the Service's endpoints. A failing readiness probe prevents traffic from being routed to a pod, even if it is otherwise healthy, which matches the symptom of fewer available pods than desired.
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
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 →
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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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