- A
Change the Service type to NodePort to bypass the Ingress.
Why wrong: Changing Service type does not affect endpoint creation; the root cause is missing endpoints.
- B
Update the Ingress to use a different backend service.
Why wrong: The Ingress is correctly configured; the issue is with the Service itself.
- C
Check the container port and readiness probe configuration; the pods may not be listening on the expected port or the readiness probe is failing.
Empty endpoints indicate no ready pods matching the selector; despite 'Ready' status, the readiness probe might be failing if not configured, or the container might not be listening on 3000.
- D
Modify the Service selector to match the pod labels exactly.
Why wrong: The selector already matches 'app: web'; this would not change anything.
CKA Services & Networking Practice Question
This CKA practice question tests your understanding of services & networking. 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.
You are tasked with troubleshooting a web application that is deployed in a Kubernetes cluster. The application consists of a Deployment named 'web-app' with 3 replicas, each running a container that listens on port 3000. A Service named 'web-service' of type ClusterIP with selector 'app: web' and port 80 targeting port 3000 has been created. Additionally, an Ingress resource named 'web-ingress' is configured with a host rule for 'example.com' and backend service 'web-service' on port 80. Users report that accessing http://example.com results in a 503 Service Unavailable error. You verify that all pods are running and ready (kubectl get pods shows 3/3 ready). The Ingress controller logs show 'upstream connect error or disconnect/reset before headers'. You check the endpoints: 'kubectl get endpoints web-service' shows no endpoints. The pods have the label 'app: web'. What should you do to resolve the issue?
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
Check the container port and readiness probe configuration; the pods may not be listening on the expected port or the readiness probe is failing.
Option C is correct because the absence of endpoints for the Service indicates that the Service's selector is not matching any pods, or the pods are not listening on the correct port. Since the pods have the label 'app: web' and the Service uses 'app: web', the issue is likely that the container port (3000) is misconfigured or the readiness probe is failing, causing the pods to be removed from the Service's endpoints. The Ingress controller's 'upstream connect error' confirms that traffic cannot reach the pods, which aligns with the missing endpoints.
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.
- ✗
Change the Service type to NodePort to bypass the Ingress.
Why it's wrong here
Changing Service type does not affect endpoint creation; the root cause is missing endpoints.
- ✗
Update the Ingress to use a different backend service.
Why it's wrong here
The Ingress is correctly configured; the issue is with the Service itself.
- ✓
Check the container port and readiness probe configuration; the pods may not be listening on the expected port or the readiness probe is failing.
Why this is correct
Empty endpoints indicate no ready pods matching the selector; despite 'Ready' status, the readiness probe might be failing if not configured, or the container might not be listening on 3000.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Modify the Service selector to match the pod labels exactly.
Why it's wrong here
The selector already matches 'app: web'; this would not change anything.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume the Service selector is wrong when endpoints are missing, but the real issue is often a readiness probe failure or a port mismatch, which the question subtly hints at by stating pods are 'running and ready' but not necessarily passing readiness checks.
Detailed technical explanation
How to think about this question
Kubernetes Endpoints are automatically populated when a Service's selector matches a pod's labels and the pod's container port matches the Service's targetPort. If a readiness probe fails, the pod is removed from the Endpoints object, even if the pod is running. The Ingress controller's 'upstream connect error' typically indicates that the backend Service has no healthy endpoints, which can be verified with 'kubectl get endpoints'. In real-world scenarios, misconfigured readiness probes (e.g., wrong path or port) are a common cause of this issue.
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 CKA 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.
- →
Services & Networking — study guide chapter
Learn the concepts, then practise the questions
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FAQ
Questions learners often ask
What does this CKA question test?
Services & Networking — This question tests Services & Networking — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Check the container port and readiness probe configuration; the pods may not be listening on the expected port or the readiness probe is failing. — Option C is correct because the absence of endpoints for the Service indicates that the Service's selector is not matching any pods, or the pods are not listening on the correct port. Since the pods have the label 'app: web' and the Service uses 'app: web', the issue is likely that the container port (3000) is misconfigured or the readiness probe is failing, causing the pods to be removed from the Service's endpoints. The Ingress controller's 'upstream connect error' confirms that traffic cannot reach the pods, which aligns with the missing endpoints.
What should I do if I get this CKA 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
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Last reviewed: Jun 11, 2026
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.
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