- A
The pods have a liveness probe that fails
Why wrong: Liveness probe failure causes pod restart, but traffic is still possible when pod is running. Readiness probe controls traffic.
- B
The Deployment replicas are set to zero
Why wrong: If replicas are zero, no pods exist; but the scenario implies pods exist but don't receive traffic.
- C
The pods have a failing readiness probe
Readiness probe determines if a pod should receive traffic. Failing removes pod from Service endpoints.
- D
The Service type is NodePort
Why wrong: NodePort works for external traffic but also internal; type alone does not block traffic.
Question 451 of 997
How a Failing Readiness Probe Removes Pods from Service Endpoints
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 cluster administrator notices that a Deployment's pods are not receiving traffic as expected. The Service selector matches the pod labels. What is a possible cause?
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
A failing readiness probe removes the pod's endpoint from the Service's EndpointSlice, so the Service stops routing traffic to that pod even though the pod is running and its labels match the Service selector. This is the most direct reason why a Deployment's pods would not receive traffic despite correct label matching.
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 pods have a liveness probe that fails
Why it's wrong here
Liveness probe failure causes pod restart, but traffic is still possible when pod is running. Readiness probe controls traffic.
- ✗
The Deployment replicas are set to zero
Why it's wrong here
If replicas are zero, no pods exist; but the scenario implies pods exist but don't receive traffic.
- ✓
The pods have a failing readiness probe
Why this is correct
Readiness probe determines if a pod should receive traffic. Failing removes pod from Service endpoints.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The Service type is NodePort
Why it's wrong here
NodePort works for external traffic but also internal; type alone does not block traffic.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The exam often tests the distinction between liveness and readiness probes, trapping candidates who confuse a liveness probe failure (which restarts the pod) with a readiness probe failure (which removes the pod from the Service's endpoint list).
Trap categories for this question
Scenario analysis trap
If replicas are zero, no pods exist; but the scenario implies pods exist but don't receive traffic.
Detailed technical explanation
How to think about this question
Readiness probes are checked by the kubelet, and when they fail, the pod's 'Ready' condition in the EndpointSlice is set to 'False', causing the kube-proxy to remove the pod's IP from the iptables/IPVS rules that direct traffic to the Service. This is defined in the Kubernetes API (core/v1) and is critical for zero-downtime deployments, where a pod must be fully initialized before receiving traffic.
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 — A failing readiness probe removes the pod's endpoint from the Service's EndpointSlice, so the Service stops routing traffic to that pod even though the pod is running and its labels match the Service selector. This is the most direct reason why a Deployment's pods would not receive traffic despite correct label matching.
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.
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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