Hands-on Lab·Certified Kubernetes Administrator
Resource Requests, Limits and QoS Classes
Requests are what the scheduler reserves. Limits are what the kernel enforces. The relationship between them assigns a QoS class you never write down, and that class decides who gets evicted first. Build all three classes, then watch a container exceed its memory limit and get killed.
Configuration and Secrets Guide 35 of 103 Intermediate
- Kubernetes1.36.4
- Cluster4 nodes, 2 CPU / 4 GB each
- Runtimecontainerd 2.2.6
- metrics-serverinstalled
- TimeAbout 30 min
- Reviewed21 August 2026
Written against the versions above. Node utilisation figures are whatever your cluster is doing at the time. The QoS assignments and the OOM behaviour are deterministic.
| Server Name | IP Address | OS | Roles | CPU | RAM | HDD |
|---|---|---|---|---|---|---|
| CKA1001 | 192.168.0.175 | Ubuntu 26.04 LTS | Control Plane Node | 2 Core | 4 GB | 50 GB |
| CKA1001-NODE01 | 192.168.0.176 | Ubuntu 26.04 LTS | Worker Node | 2 Core | 4 GB | 50 GB |
| CKA1001-NODE02 | 192.168.0.177 | Ubuntu 26.04 LTS | Worker Node | 2 Core | 4 GB | 50 GB |
| CKA1001-NODE03 | 192.168.0.178 | Ubuntu 26.04 LTS | Worker Node | 2 Core | 4 GB | 50 GB |
Before you start
- A working cluster and
kubectl. - The Pods guide. Requests and limits are fields on a container, so that is the shape you need.
metrics-serverif you wantkubectl topto work. It is not required for anything else here.
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Two numbers that do completely different jobs
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The class you never wrote
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What the scheduler actually reserved
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A memory limit is not advice
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Clean up