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Services and Networking →mediumMultiple 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 need to create a NetworkPolicy that denies all ingress traffic to pods with label 'app: db' in namespace 'prod'. Which YAML snippet correctly implements this?

Question 1mediummultiple choice
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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: deny-db namespace: prod spec: podSelector: matchLabels: app: db policyTypes: - Ingress ingress: []

To deny all ingress traffic, you create a NetworkPolicy that selects the pods and has an empty ingress rule (or no ingress rules, which denies all). The correct way is to specify podSelector with the label and have no ingress rules (or an empty ingress array).

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: deny-db namespace: prod spec: podSelector: matchLabels: app: db policyTypes: - Ingress ingress: - from: - ipBlock: cidr: 0.0.0.0/0

    Why it's wrong here

    This allows ingress from all IPs, which is the opposite of deny all.

  • ✗

    apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: deny-all namespace: prod spec: podSelector: {} policyTypes: - Ingress ingress: - from: []

    Why it's wrong here

    This selects all pods and the from rule with empty array is invalid.

  • ✗

    apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: deny-all spec: podSelector: {} policyTypes: - Ingress ingress: []

    Why it's wrong here

    This selects all pods, not just those with label 'app: db'.

  • ✓

    apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: deny-db namespace: prod spec: podSelector: matchLabels: app: db policyTypes: - Ingress ingress: []

    Why this is correct

    This selects pods with label 'app: db' in namespace 'prod' and has no ingress rules, thus denying all ingress traffic.

    Related concept

    CIDR notation defines the prefix length.

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 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 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: deny-db namespace: prod spec: podSelector: matchLabels: app: db policyTypes: - Ingress ingress: [] — To deny all ingress traffic, you create a NetworkPolicy that selects the pods and has an empty ingress rule (or no ingress rules, which denies all). The correct way is to specify podSelector with the label and have no ingress rules (or an empty ingress array).

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

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.

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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This CKAD 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 CKAD exam.