This CKA practice question tests your understanding of services & networking. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Egress rule is defined but has no allow rules, so all egress is denied.
Option A is correct because the NetworkPolicy defines an Egress rule with an empty `rules` array, which means no egress traffic is explicitly allowed. In Kubernetes, when a NetworkPolicy selects a pod, it defaults to denying all traffic of the specified direction unless explicitly allowed. Since the Egress rule has no allow rules, all outbound traffic from the selected pods, including HTTP/HTTPS requests to external websites like google.com, is blocked by the policy.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
The Egress rule is defined but has no allow rules, so all egress is denied.
Why this is correct
With policyTypes including Egress and no egress rules, all egress is denied.
Related concept
Read the scenario before looking for a memorised answer.
✗
The Ingress rule blocks all incoming traffic, preventing DNS responses.
Why it's wrong here
The problem is egress, not ingress; DNS responses are not blocked by egress rules.
✗
The policy is applied to all namespaces, causing a conflict.
Why it's wrong here
The policy is in the default namespace and only affects that namespace.
✗
The policy only applies to pods with specific labels.
Why it's wrong here
The podSelector is empty, meaning it applies to all pods.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume an empty Egress rule means 'allow all egress' or that the policy only restricts ingress, but Kubernetes NetworkPolicy defaults to deny for the specified direction when any rule of that type is present.
Detailed technical explanation
How to think about this question
Under the hood, Kubernetes NetworkPolicy uses iptables or eBPF (depending on the CNI plugin) to enforce traffic rules. When a NetworkPolicy with an Egress rule is applied, the CNI plugin installs iptables rules that drop all outbound traffic from the selected pods by default, then only allows traffic matching the specified egress rules. A common real-world scenario is when a developer creates a NetworkPolicy to restrict egress to specific IP ranges but forgets to allow DNS (UDP port 53), causing DNS resolution failures that manifest as curl failures to external sites.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
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
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CKA question in full detail.
Services & Networking — This question tests Services & Networking — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The Egress rule is defined but has no allow rules, so all egress is denied. — Option A is correct because the NetworkPolicy defines an Egress rule with an empty `rules` array, which means no egress traffic is explicitly allowed. In Kubernetes, when a NetworkPolicy selects a pod, it defaults to denying all traffic of the specified direction unless explicitly allowed. Since the Egress rule has no allow rules, all outbound traffic from the selected pods, including HTTP/HTTPS requests to external websites like google.com, is blocked by the policy.
What should I do if I get this CKA question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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