- A
ingress: - from: - ipBlock: cidr: 0.0.0.0/0
Why wrong: This allows all ingress traffic, which is too permissive.
- B
ingress: - from: - podSelector: matchLabels: app: monitoring - namespaceSelector: matchLabels: name: my-namespace
Why wrong: This allows traffic from pods with label app: monitoring in namespaces with label name: my-namespace, which is more restrictive than needed and may not match the same namespace.
- C
ingress: - from: - podSelector: matchLabels: app: monitoring
This allows ingress from pods with label app: monitoring in the same namespace.
- D
ingress: - from: - namespaceSelector: matchLabels: app: monitoring
Why wrong: namespaceSelector selects namespaces, not pods. This would allow traffic from all pods in namespaces with that label, which is not the requirement.
CKA Services and Networking Practice Question
This CKA 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 have a NetworkPolicy that denies all ingress traffic by default, and you want to allow traffic only from pods with label 'app: monitoring' in the same namespace. What should the policy spec look like?
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: - podSelector: matchLabels: app: monitoring
To allow ingress from pods with a specific label in the same namespace, you add an ingress rule with a podSelector. The default deny is implicit if no ingress rules exist, or you can explicitly set podSelector: {} to deny all. But since the question says 'denies all ingress traffic by default', you need to add an ingress rule that allows the desired pods.
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.
- ✗
ingress: - from: - ipBlock: cidr: 0.0.0.0/0
Why it's wrong here
This allows all ingress traffic, which is too permissive.
- ✗
ingress: - from: - podSelector: matchLabels: app: monitoring - namespaceSelector: matchLabels: name: my-namespace
Why it's wrong here
This allows traffic from pods with label app: monitoring in namespaces with label name: my-namespace, which is more restrictive than needed and may not match the same namespace.
- ✓
ingress: - from: - podSelector: matchLabels: app: monitoring
Why this is correct
This allows ingress from pods with label app: monitoring in the same namespace.
Related concept
CIDR notation defines the prefix length.
- ✗
ingress: - from: - namespaceSelector: matchLabels: app: monitoring
Why it's wrong here
namespaceSelector selects namespaces, not pods. This would allow traffic from all pods in namespaces with that label, which is not the requirement.
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 CKA subnetting questions on CIDR, address ranges, and subnet selection.
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FAQ
Questions learners often ask
What does this CKA 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: ingress: - from: - podSelector: matchLabels: app: monitoring — To allow ingress from pods with a specific label in the same namespace, you add an ingress rule with a podSelector. The default deny is implicit if no ingress rules exist, or you can explicitly set podSelector: {} to deny all. But since the question says 'denies all ingress traffic by default', you need to add an ingress rule that allows the desired pods.
What should I do if I get this CKA 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 CKA 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
This CKA 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 CKA exam.
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