Question 833 of 991

Services and Networking →hardMultiple ChoiceObjective-mapped

CKAD Services and Networking Practice Question

This CKAD practice question tests your understanding of services and networking. 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 want to restrict ingress traffic to pods with label 'app: web' in namespace 'frontend' to only come from pods in namespace 'backend'. Which NetworkPolicy YAML is correct?

Question 1hardmultiple choice

Full question →

A
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: allow-backend namespace: frontend spec: podSelector: matchLabels: app: web policyTypes: - Ingress ingress: - from: - namespaceSelector: matchLabels: kubernetes.io/metadata.name: backend
This selects pods with label 'app: web' in 'frontend' and allows ingress from any pod in namespace 'backend'.
B
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: allow-backend namespace: backend spec: podSelector: matchLabels: app: web ingress: - from: - namespaceSelector: matchLabels: kubernetes.io/metadata.name: frontend
Why wrong: The policy is in the wrong namespace; it should be in 'frontend' to affect pods there.
C
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: allow-backend namespace: frontend spec: podSelector: matchLabels: app: web ingress: - from: - ipBlock: cidr: 0.0.0.0/0
Why wrong: Allows all ingress, not restricted to backend namespace.
D
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: allow-backend namespace: frontend spec: podSelector: matchLabels: app: web policyTypes: - Ingress ingress: - from: - podSelector: matchLabels: app: backend
Why wrong: This selects pods based on label, but not namespace. It would only work within the same namespace.

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: allow-backend namespace: frontend spec: podSelector: matchLabels: app: web policyTypes: - Ingress ingress: - from: - namespaceSelector: matchLabels: kubernetes.io/metadata.name: backend

To allow ingress only from pods in namespace 'backend', you need to use namespaceSelector under from, and also select the pod (optional if any pod). The correct YAML has a namespaceSelector matching the namespace label for 'backend'.

Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.

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: allow-backend namespace: frontend spec: podSelector: matchLabels: app: web policyTypes: - Ingress ingress: - from: - namespaceSelector: matchLabels: kubernetes.io/metadata.name: backend
Why this is correct
This selects pods with label 'app: web' in 'frontend' and allows ingress from any pod in namespace 'backend'.
Related concept
CIDR notation defines the prefix length.
✗
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: allow-backend namespace: backend spec: podSelector: matchLabels: app: web ingress: - from: - namespaceSelector: matchLabels: kubernetes.io/metadata.name: frontend
Why it's wrong here
The policy is in the wrong namespace; it should be in 'frontend' to affect pods there.
✗
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: allow-backend namespace: frontend spec: podSelector: matchLabels: app: web ingress: - from: - ipBlock: cidr: 0.0.0.0/0
Why it's wrong here
Allows all ingress, not restricted to backend namespace.
✗
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: allow-backend namespace: frontend spec: podSelector: matchLabels: app: web policyTypes: - Ingress ingress: - from: - podSelector: matchLabels: app: backend
Why it's wrong here
This selects pods based on label, but not namespace. It would only work within the same namespace.

Common exam traps

Common exam trap: usable hosts are not the same as total addresses

Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.

Detailed technical explanation

How to think about this question

Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.

KKey Concepts to Remember

CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.

TExam Day Tips

Write the block size before choosing the subnet.
Check whether the question asks for hosts, subnets or a specific address range.
Do not confuse /24, /25, /26 and /27 host counts.

Key takeaway

Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.

Real-world example

How this comes up in practice

A network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.

What to study next

Got this wrong? Here's your next step.

Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related CKAD subnetting questions on CIDR, address ranges, and subnet selection.

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FAQ

Questions learners often ask

What does this CKAD question test?

Services and Networking — This question tests Services and Networking — CIDR notation defines the prefix length..

What is the correct answer to this question?

The correct answer is: apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: allow-backend namespace: frontend spec: podSelector: matchLabels: app: web policyTypes: - Ingress ingress: - from: - namespaceSelector: matchLabels: kubernetes.io/metadata.name: backend — To allow ingress only from pods in namespace 'backend', you need to use namespaceSelector under from, and also select the pod (optional if any pod). The correct YAML has a namespaceSelector matching the namespace label for 'backend'.

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

What is the key concept behind this question?

CIDR notation defines the prefix length.

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Last reviewed: Jun 21, 2026

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