Question 721 of 997

Monitoring, Logging and Runtime Security →mediumMultiple ChoiceObjective-mapped

How to Isolate a Compromised Pod Using NetworkPolicy

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. A key principle to apply: networkPolicy policyTypes. 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 container has been compromised. You need to isolate it by denying all network traffic. Which NetworkPolicy manifest achieves this?

A
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: isolate spec: podSelector: matchLabels: app: compromised ingress: [] egress: []
Why wrong: This policy lacks the policyTypes field. Without specifying policyTypes, the empty ingress and egress rules are not enforced, so the compromised pod remains accessible.
B
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: isolate spec: podSelector: matchLabels: app: compromised policyTypes: - Ingress ingress: - from: - podSelector: {}
Why wrong: This allows all ingress traffic from any pod.
C
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: isolate spec: podSelector: matchLabels: app: compromised policyTypes: - Egress egress: - to: - podSelector: {}
Why wrong: This allows all egress traffic to any pod.
D
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: isolate spec: podSelector: matchLabels: app: compromised policyTypes: - Ingress - Egress
Sets policyTypes to both Ingress and Egress with empty rules, which effectively denies all network traffic to and from the pod, achieving full isolation.

Full breakdown with real-world context →

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: compromised policyTypes: - Ingress - Egress

Option D correctly isolates the pod by explicitly setting policyTypes to both Ingress and Egress with empty rules. The policyTypes field is crucial: specifying 'Ingress' and 'Egress' without any rules denies all traffic in both directions. Option A omits policyTypes entirely, so while it has empty ingress and egress arrays, without policyTypes the policy does not actually enforce any rules, leaving the pod accessible. Thus only D achieves the isolation requirement.

Key principle: NetworkPolicy policyTypes

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: compromised ingress: [] egress: []
Why it's wrong here
This policy lacks the policyTypes field. Without specifying policyTypes, the empty ingress and egress rules are not enforced, so the compromised pod remains accessible.
✗
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: isolate spec: podSelector: matchLabels: app: compromised policyTypes: - Ingress ingress: - from: - podSelector: {}
Why it's wrong here
This allows all ingress traffic from any pod.
✗
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: isolate spec: podSelector: matchLabels: app: compromised policyTypes: - Egress egress: - to: - podSelector: {}
Why it's wrong here
This allows all egress traffic to any pod.
✓
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: isolate spec: podSelector: matchLabels: app: compromised policyTypes: - Ingress - Egress
Why this is correct
Sets policyTypes to both Ingress and Egress with empty rules, which effectively denies all network traffic to and from the pod, achieving full isolation.
Related concept
NetworkPolicy policyTypes

Common exam traps

Common exam trap: answer the scenario, not the keyword

Many candidates think that empty ingress and egress rules alone deny traffic, but the policyTypes field is required to activate those rules. Without policyTypes, the policy is effectively ignored.

Detailed technical explanation

How to think about this question

Treat this as a scenario question. Identify the problem, the constraint, and the best action. Then compare each option against those facts.

KKey Concepts to Remember

NetworkPolicy policyTypes
Default deny with NetworkPolicy

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

NetworkPolicy policyTypes

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 networkPolicy policyTypes, then practise related CKS questions on the same topic to reinforce the concept.

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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 — NetworkPolicy policyTypes.

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: compromised policyTypes: - Ingress - Egress — Option D correctly isolates the pod by explicitly setting policyTypes to both Ingress and Egress with empty rules. The policyTypes field is crucial: specifying 'Ingress' and 'Egress' without any rules denies all traffic in both directions. Option A omits policyTypes entirely, so while it has empty ingress and egress arrays, without policyTypes the policy does not actually enforce any rules, leaving the pod accessible. Thus only D achieves the isolation requirement.

What should I do if I get this CKS question wrong?

Review networkPolicy policyTypes, then practise related CKS questions on the same topic to reinforce the concept.

What is the key concept behind this question?

NetworkPolicy policyTypes

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Same concept, more angles

1 more ways this is tested on CKS

These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.

Variation 1. A pod has been compromised. You want to isolate it from other pods while preserving its network state for forensics. Which NetworkPolicy rule achieves this?

hard

A.Deny all ingress and egress traffic to/from the pod's namespace
✓ B.Create a NetworkPolicy with podSelector matching the compromised pod and empty ingress/egress rules (deny all)
C.Add a label to the pod and create a NetworkPolicy allowing only traffic from a forensic pod
D.Delete the pod

Why B: Option B is correct because a NetworkPolicy with a `podSelector` matching the compromised pod and empty `ingress` and `egress` rules (i.e., no rules specified) defaults to denying all traffic to and from that pod. This isolates the pod from all other pods in the cluster while preserving its network state for forensics, as the pod remains running and its network interfaces are untouched.

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