This CKS practice question tests your understanding of system hardening. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Exhibit
Refer to the exhibit.
```
$ kubectl get nodes -o yaml | grep -A10 kubeletConfig
kubeletConfig:
imageGCHighThresholdPercent: 85
imageGCLowThresholdPercent: 80
maxPods: 110
podPidsLimit: -1
resolvConf: /etc/resolv.conf
rotateCertificates: true
```
Refer to the exhibit. A security engineer sees that podPidsLimit is set to -1. What security concern does this raise?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
It disables PID limiting, allowing a single pod to consume all PIDs on the node, risking a fork bomb
Setting `podPidsLimit` to `-1` in Kubernetes disables PID limiting for pods, meaning a single pod can create an unlimited number of processes. This poses a security risk because a compromised or malicious pod could launch a fork bomb, exhausting all available PIDs on the node and causing a denial of service (DoS) for other workloads. The correct answer is C.
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.
✗
It sets a hard limit of 1 PID per pod, which may break workloads
Why it's wrong here
-1 means unlimited, not 1.
✗
It limits each container to 1000 PIDs
Why it's wrong here
podPidsLimit applies per pod, not per container.
✓
It disables PID limiting, allowing a single pod to consume all PIDs on the node, risking a fork bomb
Why this is correct
-1 disables the limit, so a pod can exhaust node PIDs.
Related concept
Read the scenario before looking for a memorised answer.
✗
It enforces a default PID limit of 100 per pod
Why it's wrong here
-1 means unlimited, not 100.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume `-1` means 'no limit' is safe or that it enforces a default, but Cisco tests the specific security implication of disabling PID limiting, which is the risk of a fork bomb and node-wide DoS.
Detailed technical explanation
How to think about this question
Under the hood, `podPidsLimit` is a kubelet configuration parameter that controls the cgroup pids.max value for each pod's cgroup. When set to `-1`, the cgroup pids.max file is written with 'max', allowing unlimited PIDs. In a real-world scenario, a container running a fork bomb (e.g., `:(){ :|:& };:`) could quickly exhaust the node's PID limit (default 32768 on Linux), crashing the kubelet and all other pods on the node.
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 practitioner preparing for the CKS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CKS question in full detail.
System Hardening — This question tests System Hardening — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: It disables PID limiting, allowing a single pod to consume all PIDs on the node, risking a fork bomb — Setting `podPidsLimit` to `-1` in Kubernetes disables PID limiting for pods, meaning a single pod can create an unlimited number of processes. This poses a security risk because a compromised or malicious pod could launch a fork bomb, exhausting all available PIDs on the node and causing a denial of service (DoS) for other workloads. The correct answer is C.
What should I do if I get this CKS 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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