- A
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: isolate spec: podSelector: matchLabels: app: busybox egress: - to: - podSelector: {}
Why wrong: This allows all egress traffic to any pod, not deny.
- B
apiVersion: v1 kind: NetworkPolicy metadata: name: isolate spec: podSelector: {} policyTypes: - Ingress
Why wrong: Empty podSelector selects all pods, not just the compromised one. Also missing Egress.
- C
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: isolate spec: podSelector: matchLabels: app: busybox ingress: - from: - podSelector: {}
Why wrong: This allows all ingress traffic from any pod, not deny.
- D
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: isolate spec: podSelector: matchLabels: app: busybox policyTypes: - Ingress - Egress
This policy selects the pod and specifies both policyTypes with no rules, which defaults to deny all ingress and egress.
CKS Monitoring, Logging and Runtime Security Practice Question
This CKS practice question tests your understanding of monitoring, logging and runtime security. 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.
A pod named 'busybox-pod' is compromised. You want to isolate it from all other pods using a NetworkPolicy. Which YAML snippet correctly denies all ingress and egress traffic to/from the pod?
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
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: isolate spec: podSelector: matchLabels: app: busybox policyTypes: - Ingress - Egress
A NetworkPolicy with podSelector matching the pod, empty ingress and egress rules (or policyTypes set to both and no rules) will deny all traffic. Option A uses the correct structure: podSelector to target the pod, policyTypes including both, and empty ingress/egress lists.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: isolate spec: podSelector: matchLabels: app: busybox egress: - to: - podSelector: {}
Why it's wrong here
This allows all egress traffic to any pod, not deny.
- ✗
apiVersion: v1 kind: NetworkPolicy metadata: name: isolate spec: podSelector: {} policyTypes: - Ingress
Why it's wrong here
Empty podSelector selects all pods, not just the compromised one. Also missing Egress.
- ✗
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: isolate spec: podSelector: matchLabels: app: busybox ingress: - from: - podSelector: {}
Why it's wrong here
This allows all ingress traffic from any pod, not deny.
- ✓
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: isolate spec: podSelector: matchLabels: app: busybox policyTypes: - Ingress - Egress
Why this is correct
This policy selects the pod and specifies both policyTypes with no rules, which defaults to deny all ingress and egress.
Related concept
Standard ACLs match source addresses.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
- Standard ACLs match source addresses.
- Extended ACLs can match source, destination, protocol and ports.
- The first matching ACL entry is used.
- There is usually an implicit deny at the end.
TExam Day Tips
- Check inbound versus outbound direction.
- Read the ACL from top to bottom.
- Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
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.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related CKS ACL questions on filtering logic and placement.
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FAQ
Questions learners often ask
What does this CKS question test?
Monitoring, Logging and Runtime Security — This question tests Monitoring, Logging and Runtime Security — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: isolate spec: podSelector: matchLabels: app: busybox policyTypes: - Ingress - Egress — A NetworkPolicy with podSelector matching the pod, empty ingress and egress rules (or policyTypes set to both and no rules) will deny all traffic. Option A uses the correct structure: podSelector to target the pod, policyTypes including both, and empty ingress/egress lists.
What should I do if I get this CKS question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related CKS ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
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Last reviewed: Jun 21, 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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