CKAD — Common Mistakes

Common Mistakes That Fail Candidates

1. Wrong Namespace

The most common mistake. Each question specifies a namespace. If you create resources in the wrong namespace, you get zero points.

# ALWAYS check the question's namespace first
# ALWAYS switch to it before working
kn <question-namespace>

# Verify after creating
k get pods -n <namespace>

2. Forgetting to Save and Apply

You edit a YAML file but forget to apply it:

# After editing, ALWAYS apply
k apply -f my-resource.yaml

# Verify it was created
k get <resource>

3. YAML Indentation Errors

YAML is indentation-sensitive. A single space off can cause errors.

# WRONG - containers is under metadata
metadata:
  name: my-pod
  containers:       # This is WRONG
  - name: app

# CORRECT - containers is under spec
metadata:
  name: my-pod
spec:
  containers:       # This is CORRECT
  - name: app

4. Using the Wrong apiVersion

# Check the correct apiVersion
k api-resources | grep Ingress
# Expected: Ingress ... networking.k8s.io/v1

# Or use explain
k explain ingress

5. Not Verifying Your Work

Always verify after creating resources:

# Check it exists
k get <resource>

# Check it is running/ready
k get pods   # Look for Running, Ready 1/1

# Check events for errors
k describe <resource> | tail -20

6. Port Confusion

Field	Meaning
containerPort	Port the container listens on (informational in Pod spec)
targetPort	Port traffic is sent to (in Service spec — must match containerPort)
port	Port the Service listens on
nodePort	External port on each node (NodePort Service)

7. Forgetting DNS Rules for Cross-Namespace Access

# Same namespace: just the service name
curl http://web

# Different namespace: service.namespace
curl http://web.production

# Not: curl http://web (this only works in the same namespace)

8. Not Reading the Entire Question

Questions sometimes have multiple parts. Read the entire question before starting. Some students complete part 1 and skip parts 2 and 3.

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Next: Mock Exam — Part 1 →