Node troubleshooting in Kubernetes - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the command to list all nodes in the Kubernetes cluster.

Kubernetes

kubectl get [1]

Drag options to blanks, or click blank then click option'

Aservices

Bnodes

Cpods

Ddeployments

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'pods' instead of 'nodes' will list pods, not nodes.

Using 'services' or 'deployments' will show other resources, not nodes.

The command kubectl get nodes lists all nodes in the cluster.

2fill in blank

medium

Complete the command to describe a node named 'worker-1' to see detailed info.

Kubernetes

kubectl [1] node worker-1

Drag options to blanks, or click blank then click option'

Adescribe

Bexec

Clogs

Dget

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'get' shows summary info, not detailed.

Using 'logs' or 'exec' are for pods, not nodes.

The describe command shows detailed information about a node, including events and status.

3fill in blank

hard

Fix the error in the command to check node status by filling the missing flag.

Kubernetes

kubectl get nodes -o [1]

Drag options to blanks, or click blank then click option'

Awide

Byaml

Cjson

Djsonpath

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'json' or 'yaml' outputs data in formats harder to read quickly.

Using 'jsonpath' requires a query expression.

The -o wide option shows extra columns like internal IP and node status.

4fill in blank

hard

Fill both blanks to create a command that shows node labels and filters nodes with label 'env=prod'.

Kubernetes

kubectl get nodes -L [1] --selector=[2]

Drag options to blanks, or click blank then click option'

Aenv

Benv=prod

Czone=us-east

Drole=worker

Attempts:

3 left

💡 Hint

Common Mistakes

Using a label name in the selector that doesn't match the label column.

Mixing label keys and values incorrectly.

The -L env option shows the 'env' label column, and --selector=env=prod filters nodes with that label.

5fill in blank

hard

Fill all three blanks to create a command that cordons a node, drains it, and then deletes it.

Kubernetes

kubectl [1] node worker-2 && kubectl [2] node worker-2 --ignore-daemonsets --delete-local-data && kubectl [3] node worker-2

Drag options to blanks, or click blank then click option'

Acordon

Bdrain

Cdelete

Duncordon

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'uncordon' instead of 'cordon' will allow scheduling, opposite of what is needed.

Skipping the drain step can cause pod disruption.

Deleting before draining can cause errors.

First, cordon marks the node unschedulable. Then, drain safely evicts pods. Finally, delete removes the node from the cluster.

Practice

1. What command shows the current status of all nodes in a Kubernetes cluster?

easy

A. kubectl get nodes

B. kubectl describe pods

C. kubectl get pods

D. kubectl top pods

Solution

1. Step 1: Understand the command purpose

   kubectl get nodes lists all nodes and their status in the cluster.

2. Step 2: Compare with other commands

   Other commands focus on pods, not nodes, so they don't show node status.

3. Final Answer:

   kubectl get nodes -> Option A

4. Quick Check:

   Node status = kubectl get nodes [OK]

Hint: Use 'kubectl get nodes' to see node status quickly [OK]

Common Mistakes:

• Confusing pods with nodes
• Using describe instead of get for quick status
• Trying 'kubectl top pods' for node info

2. Which command syntax correctly shows detailed information about a specific node named node-1?

easy

A. kubectl describe node node-1

B. kubectl get node node-1

C. kubectl get nodes node-1

D. kubectl describe nodes node-1

Solution

1. Step 1: Identify correct command for detailed info

   kubectl describe node node-1 shows detailed info about the node named node-1.

2. Step 2: Check syntax correctness

   Singular 'node' is correct here; plural 'nodes' is invalid for describing a single node. 'get' shows summary, not details.

3. Final Answer:

   kubectl describe node node-1 -> Option A

4. Quick Check:

   Detailed node info = kubectl describe node [OK]

Hint: Use singular 'node' with describe for a specific node [OK]

Common Mistakes:

• Using plural 'nodes' with describe for a single node
• Using 'get' instead of 'describe' for details
• Omitting the node name

3. What is the expected output of the command kubectl top node?

medium

A. A list of pods with their resource requests

B. A list of nodes with CPU and memory usage metrics

C. Detailed node configuration and labels

D. A list of nodes with their IP addresses only

Solution

1. Step 1: Understand the purpose of 'kubectl top node'

   This command shows resource usage like CPU and memory for each node.

2. Step 2: Differentiate from other outputs

   It does not show pod info, detailed config, or just IP addresses.

3. Final Answer:

   A list of nodes with CPU and memory usage metrics -> Option B

4. Quick Check:

   Resource usage per node = kubectl top node [OK]

Hint: Top command shows resource usage, not config or IPs [OK]

Common Mistakes:

• Confusing node metrics with pod metrics
• Expecting detailed config from 'top' command
• Thinking it shows only IP addresses

4. You run kubectl describe node node-2 and see the node is in NotReady state. What is the best first step to troubleshoot?

medium

A. Run kubectl get pods to check pod status

B. Delete the node from the cluster immediately

C. Restart all pods on the node manually

D. Check the node's events section for errors or warnings

Solution

1. Step 1: Review node events for clues

   The events section in the describe output shows recent errors or warnings causing NotReady state.

2. Step 2: Avoid premature actions

   Deleting node or restarting pods without info can cause disruption; checking events is safer first step.

3. Final Answer:

   Check the node's events section for errors or warnings -> Option D

4. Quick Check:

   Check events first when node NotReady [OK]

Hint: Look at node events to find issues first [OK]

Common Mistakes:

• Deleting node without diagnosis
• Restarting pods blindly
• Checking pods instead of node events first

5. A node shows high CPU usage and pods are evicted frequently. Which combined steps help troubleshoot and fix this?

hard

A. Scale down all deployments to zero immediately

B. Delete the node and recreate it to reset CPU usage

C. Use kubectl top node to confirm CPU load, then check pod resource requests and limits

D. Run kubectl describe pod on all pods to find errors

Solution

1. Step 1: Confirm node CPU usage

   Run kubectl top node to verify high CPU load on the node.

2. Step 2: Check pod resource settings

   Review pods' resource requests and limits to see if they are causing CPU overload and evictions.

3. Step 3: Adjust resources or scale pods

   Based on findings, adjust pod resource limits or scale workloads to reduce CPU pressure.

4. Final Answer:

   Use kubectl top node to confirm CPU load, then check pod resource requests and limits -> Option C

5. Quick Check:

   Check CPU usage and pod limits to fix evictions [OK]

Hint: Check node CPU then pod limits to fix evictions [OK]

Common Mistakes:

• Deleting node without analysis
• Scaling down all deployments blindly
• Checking pods errors without resource context