- A
Ensure Service A's pod has the label 'app: frontend' on its pod spec
The NetworkPolicy uses podSelector to match pods with label 'app: frontend'. Service A's pod must have this label to be allowed ingress into the backend namespace.
- B
Add a similar NetworkPolicy in the 'default' namespace allowing egress to the 'backend' namespace
Why wrong: The ingress policy is already in place in the backend namespace. Unless there is an egress policy blocking traffic, no extra policy is needed in the source namespace.
- C
Change the NetworkPolicy to allow all ingress traffic from any source
Why wrong: This would work but is less secure and not the minimal change required.
- D
Add a label to the 'default' namespace matching the NetworkPolicy's namespaceSelector
Why wrong: The NetworkPolicy does not use a namespaceSelector; it uses a podSelector. Therefore, labeling the namespace is not needed.
KCNA Container Orchestration Practice Question
This KCNA practice question tests your understanding of container orchestration. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 have a microservices application where Service A needs to communicate with Service B running in a different namespace ('backend'). Both namespaces have a NetworkPolicy that denies all ingress by default. You create a NetworkPolicy in the 'backend' namespace allowing ingress from pods with label 'app: frontend'. What else is needed for Service A to reach Service B?
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
Ensure Service A's pod has the label 'app: frontend' on its pod spec
Option A is correct because NetworkPolicies use pod selectors to determine which pods are allowed to send or receive traffic. By default, a NetworkPolicy that allows ingress from pods with label 'app: frontend' will only match pods in the same namespace unless a namespaceSelector is also specified. Since Service A is in a different namespace, the only way to match the ingress rule is to ensure Service A's pod carries the label 'app: frontend'. This satisfies the podSelector in the NetworkPolicy, allowing traffic from that specific pod to Service B.
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.
- ✓
Ensure Service A's pod has the label 'app: frontend' on its pod spec
Why this is correct
The NetworkPolicy uses podSelector to match pods with label 'app: frontend'. Service A's pod must have this label to be allowed ingress into the backend namespace.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Add a similar NetworkPolicy in the 'default' namespace allowing egress to the 'backend' namespace
Why it's wrong here
The ingress policy is already in place in the backend namespace. Unless there is an egress policy blocking traffic, no extra policy is needed in the source namespace.
- ✗
Change the NetworkPolicy to allow all ingress traffic from any source
Why it's wrong here
This would work but is less secure and not the minimal change required.
- ✗
Add a label to the 'default' namespace matching the NetworkPolicy's namespaceSelector
Why it's wrong here
The NetworkPolicy does not use a namespaceSelector; it uses a podSelector. Therefore, labeling the namespace is not needed.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the misconception that NetworkPolicy podSelectors automatically apply across namespaces, when in fact they are namespace-scoped unless combined with a namespaceSelector.
Detailed technical explanation
How to think about this question
Under the hood, Kubernetes NetworkPolicy rules are enforced by the CNI plugin (e.g., Calico, Cilium) using iptables or eBPF. The podSelector in a NetworkPolicy is scoped to the namespace where the policy is defined; to allow cross-namespace traffic, you must either use a namespaceSelector in combination with a podSelector or ensure the source pod's label matches the podSelector. A common real-world scenario is when a frontend service in a 'frontend' namespace needs to reach a backend service in a 'backend' namespace; the backend's NetworkPolicy must explicitly allow ingress from pods with the correct label, and the frontend pods must carry that label.
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?
Container Orchestration — This question tests Container Orchestration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Ensure Service A's pod has the label 'app: frontend' on its pod spec — Option A is correct because NetworkPolicies use pod selectors to determine which pods are allowed to send or receive traffic. By default, a NetworkPolicy that allows ingress from pods with label 'app: frontend' will only match pods in the same namespace unless a namespaceSelector is also specified. Since Service A is in a different namespace, the only way to match the ingress rule is to ensure Service A's pod carries the label 'app: frontend'. This satisfies the podSelector in the NetworkPolicy, allowing traffic from that specific pod to Service B.
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
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Last reviewed: Jun 30, 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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