- A
ingress: - from: - namespaceSelector: matchLabels: name: ingress podSelector: matchLabels: app: ingress
Why wrong: The namespace label 'kubernetes.io/metadata.name' is the standard; using 'name' may not match.
- B
ingress: - from: - namespaceSelector: matchLabels: app: ingress podSelector: {}
Why wrong: This selects all pods in namespaces with label 'app: ingress', not the specific namespace.
- C
ingress: - from: - podSelector: matchLabels: app: ingress - namespaceSelector: matchLabels: kubernetes.io/metadata.name: ingress
Why wrong: This uses multiple 'from' items, which are OR'd, not AND'd.
- D
ingress: - from: - namespaceSelector: matchLabels: kubernetes.io/metadata.name: ingress podSelector: matchLabels: app: ingress
This allows ingress only from pods matching both selectors; default deny is implied if no other rules.
NetworkPolicy: Deny Ingress Except from Specific Namespace and Pod Labels (AND Logic)
This CKS practice question tests your understanding of minimize microservice vulnerabilities. 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 need to create a NetworkPolicy that denies all ingress traffic to pods with label 'app: web' in the 'frontend' namespace, except for traffic from pods with label 'app: ingress' in the 'ingress' namespace. Which NetworkPolicy spec correctly achieves this?
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
ingress: - from: - namespaceSelector: matchLabels: kubernetes.io/metadata.name: ingress podSelector: matchLabels: app: ingress
Option D is correct because it uses a single `from` entry with both a `namespaceSelector` (matching the `ingress` namespace by its `kubernetes.io/metadata.name` label) and a `podSelector` (matching pods with `app: ingress`). This combination restricts ingress traffic to only pods that are both in the `ingress` namespace AND have the label `app: ingress`, while implicitly denying all other ingress traffic to pods labeled `app: web` in the `frontend` namespace.
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.
- ✗
ingress: - from: - namespaceSelector: matchLabels: name: ingress podSelector: matchLabels: app: ingress
Why it's wrong here
The namespace label 'kubernetes.io/metadata.name' is the standard; using 'name' may not match.
- ✗
ingress: - from: - namespaceSelector: matchLabels: app: ingress podSelector: {}
Why it's wrong here
This selects all pods in namespaces with label 'app: ingress', not the specific namespace.
- ✗
ingress: - from: - podSelector: matchLabels: app: ingress - namespaceSelector: matchLabels: kubernetes.io/metadata.name: ingress
Why it's wrong here
This uses multiple 'from' items, which are OR'd, not AND'd.
- ✓
ingress: - from: - namespaceSelector: matchLabels: kubernetes.io/metadata.name: ingress podSelector: matchLabels: app: ingress
Why this is correct
This allows ingress only from pods matching both selectors; default deny is implied if no other rules.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
A common trap in CKS is to confuse AND vs OR logic in NetworkPolicy selectors. Option C uses separate 'from' entries (OR logic), making it overly permissive, while the correct approach combines namespaceSelector and podSelector in a single 'from' block (AND logic).
Detailed technical explanation
How to think about this question
In Kubernetes NetworkPolicy, when both `namespaceSelector` and `podSelector` are specified within the same `from` block, they are ANDed — traffic must originate from a pod that matches both selectors. This is critical for multi-tenant clusters where you need to restrict cross-namespace access to specific pods. The `kubernetes.io/metadata.name` label is automatically added by Kubernetes 1.21+ to every namespace, making it a reliable selector for namespace identity, unlike custom labels which may not exist.
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 security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this CKS question test?
Minimize Microservice Vulnerabilities — This question tests Minimize Microservice Vulnerabilities — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: ingress: - from: - namespaceSelector: matchLabels: kubernetes.io/metadata.name: ingress podSelector: matchLabels: app: ingress — Option D is correct because it uses a single `from` entry with both a `namespaceSelector` (matching the `ingress` namespace by its `kubernetes.io/metadata.name` label) and a `podSelector` (matching pods with `app: ingress`). This combination restricts ingress traffic to only pods that are both in the `ingress` namespace AND have the label `app: ingress`, while implicitly denying all other ingress traffic to pods labeled `app: web` in the `frontend` namespace.
What should I do if I get this CKS 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.
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Last reviewed: Jul 4, 2026
This CKS 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 CKS exam.
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