This CKA practice question tests your understanding of services & networking. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Exhibit
Refer to the exhibit.
```
$ kubectl describe svc my-service
Name: my-service
Namespace: default
Labels: <none>
Annotations: <none>
Selector: app=my-app
Type: ClusterIP
IP Family Policy: SingleStack
IP Families: IPv4
IP: 10.96.100.10
IPs: 10.96.100.10
Port: http 80/TCP
TargetPort: 8080/TCP
Endpoints: <none>
```
A pod in the same namespace tries to reach 'my-service' on port 80, but gets 'Connection refused'. The pod's labels are 'app: my-app'. 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 the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
No pods match the selector or the matching pods are not ready.
A 'Connection refused' error indicates that the TCP connection request reached the target IP and port, but no process was listening there. For a Kubernetes Service, this most commonly occurs when the Service's selector does not match any pod labels, or the matching pods are not in a Ready state, so the endpoints controller does not populate the Service's endpoints list, and kube-proxy has no backends to forward traffic to.
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 Service type is ClusterIP, which cannot be accessed from within the cluster.
Why it's wrong here
ClusterIP is designed for internal access.
✓
No pods match the selector or the matching pods are not ready.
Why this is correct
Endpoints are empty, so no ready pods are available.
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 targetPort is 8080, but the container port is not 8080.
Why it's wrong here
The exhibit does not show container ports, but if it were wrong, endpoints would still exist but traffic would fail.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse 'Connection refused' with 'Connection timeout' — the former indicates the Service IP was reached but no backend is listening, while the latter would suggest network-level blocking or incorrect DNS resolution.
Trap categories for this question
Command / output trap
The exhibit does not show container ports, but if it were wrong, endpoints would still exist but traffic would fail.
Detailed technical explanation
How to think about this question
When a Service is created, the endpoints controller watches for pods matching the Service's label selector and checks their readiness. Only pods with a Ready status are added to the Endpoints object. kube-proxy then programs iptables or IPVS rules to forward traffic to those endpoints. If no endpoints exist, the Service's ClusterIP is reachable but the connection is refused because there is no backend to accept it. You can verify this with 'kubectl get endpoints <service-name>' to see if the endpoint list is empty.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CKA question in full detail.
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: No pods match the selector or the matching pods are not ready. — A 'Connection refused' error indicates that the TCP connection request reached the target IP and port, but no process was listening there. For a Kubernetes Service, this most commonly occurs when the Service's selector does not match any pod labels, or the matching pods are not in a Ready state, so the endpoints controller does not populate the Service's endpoints list, and kube-proxy has no backends to forward traffic to.
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.
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.
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