Correct Answer:

See the Explanation below for complete solution
Explanation:
Below is the CKS exam style "do-this-exactly" runbook for Q3. It includes the minimal discovery commands (so you don't guess filenames), then the exact lines/blocks to set.
QUESTION 3 - ImagePolicyWebhook (Validating Admission) - Exam Steps
0) SSH + root
ssh cks000002
sudo -i
1) Identify the provided config files (no guessing)
ls -la /etc/kubernetes/bouncer
You are looking for files typically named like:
admission_configuration.yaml (AdmissionConfiguration)
imagepolicywebhook.yaml (ImagePolicyWebhookConfiguration) OR the ImagePolicyWebhook config embedded inside the AdmissionConfiguration kubeconfig (webhook kubeconfig) If unsure which is which, quick peek:
grep -R "ImagePolicyWebhook" -n /etc/kubernetes/bouncer
grep -R "AdmissionConfiguration" -n /etc/kubernetes/bouncer
grep -R "kubeconfig" -n /etc/kubernetes/bouncer
PART A - Reconfigure API Server to enable required admission plugin(s)
2) Edit API server static pod manifest
vi /etc/kubernetes/manifests/kube-apiserver.yaml
2.1 Enable the admission plugin ImagePolicyWebhook
Find the line starting with:
- --enable-admission-plugins=
Ensure ImagePolicyWebhook is included in that comma list.
Example (your list may differ; just add ImagePolicyWebhook):
- --enable-admission-plugins=NodeRestriction,ImagePolicyWebhook
If the flag does not exist, add one line under command::
- --enable-admission-plugins=ImagePolicyWebhook
2.2 Point API server to the provided AdmissionConfiguration
In the same file, ensure this flag exists (use the file in /etc/kubernetes/bouncer that contains AdmissionConfiguration):
- --admission-control-config-file=/etc/kubernetes/bouncer/admission_configuration.yaml If your file is named differently, use the real filename you found in step 1, but keep the flag name exactly --admission-control-config-file.
Save/exit:
:wq
Static pod will restart automatically (kubelet watches the manifest).
Optional quick watch:
docker ps | grep kube-apiserver
# or:
crictl ps | grep kube-apiserver
PART B - Configure ImagePolicyWebhook to deny images on backend failure
3) Edit the ImagePolicyWebhook config
One of these is true on your cluster:
Option 1 (most common in these tasks): ImagePolicyWebhook config is a standalone file Edit the file in /etc/kubernetes/bouncer that contains kind: ImagePolicyWebhookConfiguration:
grep -R "kind: ImagePolicyWebhookConfiguration" -n /etc/kubernetes/bouncer vi /etc/kubernetes/bouncer/<THE_FILE_YOU_FOUND>.yaml Set (or ensure) exactly:
defaultAllow: false
Option 2: ImagePolicyWebhook config is embedded inside AdmissionConfiguration Edit the AdmissionConfiguration file:
vi /etc/kubernetes/bouncer/admission_configuration.yaml
Find the plugin section for ImagePolicyWebhook and ensure the config includes:
defaultAllow: false
✅ Save/exit:
:wq
PART C - Point backend configuration to https://smooth-yak.local/review
4) Edit the webhook kubeconfig to use the scanner endpoint
Find the kubeconfig file referenced by the ImagePolicyWebhook config.
Search for kubeConfigFile:
grep -R "kubeConfigFile" -n /etc/kubernetes/bouncer
Open that kubeconfig path (example name below; yours may differ):
vi /etc/kubernetes/bouncer/kubeconfig
In kubeconfig, set the cluster server exactly:
clusters:
- cluster:
server: https://smooth-yak.local/review
✅ Save/exit:
:wq
PART D - Restart effect (make sure API server picks up config)
Because you already edited /etc/kubernetes/manifests/kube-apiserver.yaml, the API server restarted.
To be safe (and fast), force a restart by "touching" the manifest (no content change needed):
touch /etc/kubernetes/manifests/kube-apiserver.yaml
PART E - Test: apply vulnerable workload and confirm it is denied
5) Use admin kubeconfig (because old kubectl config may break)
export KUBECONFIG=/etc/kubernetes/admin.conf
kubectl get nodes
6) Deploy the test resource (should be DENIED)
kubectl apply -f /home/candidate/vulnerable.yaml
Expected: admission error/denied message.
If it already exists:
kubectl delete -f /home/candidate/vulnerable.yaml
kubectl apply -f /home/candidate/vulnerable.yaml
PART F - Verify the scanner was called (log check)
7) Check scanner access log
tail -n 50 /var/log/nginx/access_log
You should see requests hitting /review.
Quick "what to check if it doesn't deny"
Run these in order:
Confirm API server flags:
grep -n "enable-admission-plugins" /etc/kubernetes/manifests/kube-apiserver.yaml grep -n "admission-control-config-file" /etc/kubernetes/manifests/kube-apiserver.yaml Confirm deny-on-failure:
grep -R "defaultAllow" -n /etc/kubernetes/bouncer
Must show:
defaultAllow: false
Confirm endpoint:
grep -R "server: https://smooth-yak.local/review" -n /etc/kubernetes/bouncer API server logs (docker runtime):
docker ps | grep kube-apiserver
docker logs $(docker ps -q --filter name=kube-apiserver) --tail 80
If you paste the output of:
ls -/etc/kubernetes/bouncer
grep -R "kind: AdmissionConfiguration" -n /etc/kubernetes/bouncer
grep -R "ImagePolicyWebhook" -n /etc/kubernetes/bouncer

Correct Answer:

You can create a "default" isolation policy for a namespace by creating a NetworkPolicy that selects all pods but does not allow any ingress traffic to those pods.
---
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
name: default-deny-ingress
spec:
podSelector: {}
policyTypes:
- Ingress
You can create a "default" egress isolation policy for a namespace by creating a NetworkPolicy that selects all pods but does not allow any egress traffic from those pods.
---
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
name: allow-all-egress
spec:
podSelector: {}
egress:
- {}
policyTypes:
- Egress
Default deny all ingress and all egress traffic
You can create a "default" policy for a namespace which prevents all ingress AND egress traffic by creating the following NetworkPolicy in that namespace.
---
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
name: default-deny-all
spec:
podSelector: {}
policyTypes:
- Ingress
- Egress
This ensures that even pods that aren't selected by any other NetworkPolicy will not be allowed ingress or egress traffic.

Correct Answer:

To add a Kubernetes cluster to your project, group, or instance:
Navigate to your:
Project's Operations > Kubernetes page, for a project-level cluster.
Group's Kubernetes page, for a group-level cluster.
Admin Area > Kubernetes page, for an instance-level cluster.
Click Add Kubernetes cluster.
Click the Add existing cluster tab and fill in the details:
Kubernetes cluster name (required) - The name you wish to give the cluster.
Environment scope (required) - The associated environment to this cluster.
API URL (required) - It's the URL that GitLab uses to access the Kubernetes API. Kubernetes exposes several APIs, we want the "base" URL that is common to all of them. For example, https://kubernetes.example.com rather than https://kubernetes.example.com/api/v1.
Get the API URL by running this command:
kubectl cluster-info | grep -E 'Kubernetes master|Kubernetes control plane' | awk '/http/ {print $NF}' CA certificate (required) - A valid Kubernetes certificate is needed to authenticate to the cluster. We use the certificate created by default.
List the secrets with kubectl get secrets, and one should be named similar to default-token-xxxxx. Copy that token name for use below.
Get the certificate by running this command:
kubectl get secret <secret name> -o jsonpath="{['data']['ca\.crt']}"

Correct Answer:

SeetheExplanationbelowExplanation:
ssh-add ~/.ssh/tempprivate
eval "$(ssh-agent -s)"
cd contrib/terraform/aws
vi terraform.tfvars
terraform init
terraform apply -var-file=credentials.tfvars
ansible-playbook -i ./inventory/hosts ./cluster.yml -e ansible_ssh_user=core -e bootstrap_os=coreos -b --become-user=root --flush-cache -e ansible_user=core

Correct Answer:

See the Explanation belowExplanation:
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
name: network-policy
spec:
podSelector: {} #selects all the pods in the namespace deployed
policyTypes:
- Ingress
ingress:
- ports: #in input traffic allowed only through 80 port only
- protocol: TCP
port: 80