Memory requests and limits in Kubernetes - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Memory Requests vs Limits

In Kubernetes, what happens if a container uses more memory than its memory request but less than its memory limit?

A The container is terminated immediately by the system.

B The container may be evicted depending on node pressure.

C The container is allowed to use the extra memory without any restrictions.

D The container's CPU usage is limited but memory usage is ignored.

💡 Hint

Think about how Kubernetes manages resources when the node is under memory pressure.

Memory requests define the guaranteed memory for a container. If usage goes above the request but below the limit, the container can continue running but may be evicted if the node runs low on memory.

💻 Command Output

intermediate

Check Memory Limits in a Pod

You run the command kubectl describe pod mypod. Which section shows the memory requests and limits for containers?

Kubernetes

kubectl describe pod mypod

A In the <strong>Volumes</strong> section describing storage.

B Under the <strong>Events</strong> section at the bottom of the output.

C In the <strong>Conditions</strong> section near the top.

D Under the <strong>Containers</strong> section, look for <code>Limits:</code> and <code>Requests:</code> lines.

💡 Hint

Memory settings are part of container resource specifications.

The kubectl describe pod command shows resource requests and limits under each container's details in the Containers section.

❓ Configuration

advanced

YAML for Memory Requests and Limits

Which YAML snippet correctly sets a memory request of 256Mi and a memory limit of 512Mi for a container?

A

resources:
  requests:
    memory: 256MB
  limits:
    memory: 512MB

B

resources:
  memory:
    request: 256Mi
    limit: 512Mi

C

resources:
  requests:
    memory: "256Mi"
  limits:
    memory: "512Mi"

D

resources:
  requests:
    memory: 256
  limits:
    memory: 512

💡 Hint

Check the correct indentation and units for memory in Kubernetes YAML.

Memory requests and limits must be under resources.requests.memory and resources.limits.memory with units like Mi (mebibytes).

❓ Troubleshoot

advanced

Pod Evicted Due to Memory Limit

A pod is repeatedly evicted with the message OOMKilled. What is the most likely cause?

A The pod's memory usage exceeded its memory limit.

B The pod's disk space was full.

C The pod's CPU usage exceeded its CPU request.

D The pod's network bandwidth was exceeded.

💡 Hint

OOMKilled means Out Of Memory killed by the system.

When a container uses more memory than its limit, the system kills it to protect the node.

✅ Best Practice

expert

Setting Memory Requests and Limits for Stability

Which practice helps ensure stable Kubernetes cluster performance regarding memory requests and limits?

A Set memory requests based on typical usage and limits slightly above peak usage to balance stability and flexibility.

B Set memory requests low and limits very high to allow containers to burst freely.

C Set memory requests equal to limits for all containers to avoid resource contention.

D Do not set memory requests or limits and let Kubernetes manage automatically.

💡 Hint

Think about balancing guaranteed resources and flexibility.

Setting requests based on typical usage ensures guaranteed resources, while limits above peak usage prevent excessive memory use and evictions.