CKS Practice Exam 3 — 20 Questions

Question 1

Which TWO container sandboxing technologies are supported in Kubernetes via RuntimeClass? (Choose two)

Accepted Answer

gVisor (runsc). gVisor (runsc) is a container sandboxing technology that provides a user-space kernel for containers, isolating them from the host kernel. Kubernetes supports gVisor via RuntimeClass, allowing pods to be scheduled with the 'runsc' runtime for enhanced security.

Answer

Docker

Answer

containerd

Answer

runc

Question 2

You need to ensure that all pods in a namespace have the label 'security: high' added automatically upon creation. Which admission controller should you use?

Accepted Answer

MutatingWebhookConfiguration. A MutatingWebhookConfiguration intercepts pod creation requests and can automatically add the label 'security: high' to pods in a namespace. This admission controller mutates the object before it is persisted, ensuring all pods receive the label without manual intervention.

Answer

PodSecurityPolicy (deprecated)

Answer

ResourceQuota

Answer

ValidatingAdmissionPolicy

Question 3

Which TWO of the following are valid methods to securely manage secrets in Kubernetes?

Accepted Answer

Use Kubernetes Secrets with encryption at rest enabled. Kubernetes Secrets can be encrypted at rest using a KMS provider (e.g., AWS KMS, Azure Key Vault, or GCP Cloud KMS) configured via the EncryptionConfiguration resource. This ensures that Secret data is encrypted in etcd, protecting it from unauthorized access if the etcd database is compromised. Encryption at rest is a critical security control for secrets in Kubernetes.

Answer

Store secrets in ConfigMaps and use them in pods

Answer

Commit secrets to a private Git repository

Answer

Store secrets directly in the application code

Question 4

Which TWO of the following are valid ways to enforce that a container runs as a non-root user?

Accepted Answer

Set runAsNonRoot: true in the pod securityContext. Setting `runAsNonRoot: true` in the pod's `securityContext` explicitly instructs the kubelet to validate that the container's user ID is not 0 (root) before starting the container. If the container attempts to run as root, the kubelet will refuse to start it, providing a strong enforcement mechanism at the Kubernetes level.

Answer

Set the container image to use a root user

Answer

Use a PodSecurityPolicy (PSP)

Answer

Set runAsUser: 0 in the container securityContext

Question 5

Which TWO of the following are valid methods to verify the integrity of a container image? (Select 2)

Accepted Answer

Compare the image SHA digest with a known good digest. Container images are identified by a content-addressable digest (SHA256 hash) that uniquely represents the image manifest. Verifying that the SHA digest of a pulled image matches a known good digest from a trusted source ensures the image has not been tampered with or altered in transit, as any change to the image layers or configuration would result in a different digest.

Answer

Use trivy image to check for vulnerabilities

Answer

Use docker history to view layers

Answer

Use kubectl describe pod to check image details

Question 6

Which two of the following are correct ways to enforce least privilege for service accounts? (Choose two.)

Accepted Answer

Set automountServiceAccountToken: false in Pod spec for pods that do not need API access. Setting `automountServiceAccountToken: false` in the Pod spec prevents the automatic mounting of the service account token into the container. This enforces least privilege by ensuring that pods which do not require API access cannot inadvertently use the token to authenticate to the Kubernetes API server, reducing the attack surface.

Answer

Add multiple ClusterRoleBindings to a single service account to ensure it has access to all resources

Answer

Use the default service account for all workloads

Answer

Grant cluster-admin ClusterRole to the service account for simplicity

Question 7

An admin runs 'kubectl run nginx --image=nginx' and the pod fails with 'ImagePullBackOff'. The cluster has an OPA/Gatekeeper constraint that only allows images from 'myregistry.io'. How can the admin quickly test the restriction?

Accepted Answer

Use an image from 'myregistry.io/nginx:latest'. The OPA/Gatekeeper constraint explicitly restricts allowed images to those from 'myregistry.io'. By specifying an image from that registry (e.g., 'myregistry.io/nginx:latest'), the admin can quickly verify that the constraint permits compliant images. This tests the policy's intended behavior without altering or bypassing the constraint.

Answer

Delete the OPA constraint

Answer

Add a label 'allowlist=true' to the pod

Answer

Use 'kubectl run nginx --image=nginx --validate=false'

Question 8

Which THREE of the following are best practices for securing a Kubernetes cluster using OPA Gatekeeper? (Choose three.)

Accepted Answer

Enforce that containers set runAsNonRoot: true.. Enforcing `runAsNonRoot: true` via OPA Gatekeeper ensures that containers run with a non-root user ID, mitigating the risk of privilege escalation attacks. This aligns with the Kubernetes Pod Security Standards (PSS) 'restricted' profile and is a key control for minimizing microservice vulnerabilities.

Answer

Allow privileged containers for system-critical workloads.

Answer

Allow containers to use hostNetwork for easier service discovery.

Question 9

Which TWO resources can be used to implement RBAC in Kubernetes?

Accepted Answer

ClusterRole. A is correct because ClusterRole is a Kubernetes RBAC resource that defines a set of permissions (rules) that are not namespaced, allowing cluster-wide access. RBAC in Kubernetes uses Role and ClusterRole objects to specify allowed verbs (e.g., get, list, create) on resources (e.g., pods, secrets), and they are bound to subjects via RoleBinding or ClusterRoleBinding.

Answer

NetworkPolicy

Answer

PodSecurityPolicy

Answer

ServiceAccount

Question 10

Which TWO of the following are effective measures to harden the Kubernetes API server against unauthorized access?

Accepted Answer

Enable the NodeRestriction admission controller. The NodeRestriction admission controller limits the Node and Pod objects a kubelet can modify, preventing compromised nodes from accessing or modifying resources beyond their own. This is a key hardening measure because it enforces the principle of least privilege directly within the API server's admission chain, reducing the blast radius of a node compromise.

Answer

Set --anonymous-auth=true to allow all users

Answer

Enable audit logging to detect unauthorized attempts

Answer

Disable all authentication mechanisms and rely on network policies

Question 11

Which TWO are valid stages in a Kubernetes audit event? (Select 2)

Accepted Answer

RequestReceived. 'RequestReceived' is one of the defined stages in the Kubernetes audit event lifecycle. When an audit policy is configured, the kube-apiserver records an audit event at the 'RequestReceived' stage after it has received the request but before it has been processed by the admission controllers or the resource handler. This stage captures the raw request as it arrives.

Answer

PreProcessing

Answer

None

Answer

PostProcessing

Question 12

Which THREE of the following are correct statements about seccomp in Kubernetes? (Select 3)

Accepted Answer

Seccomp can be configured using the securityContext.seccompProfile field. The `securityContext.seccompProfile` field in a Pod or container spec allows you to configure seccomp profiles directly in the Kubernetes API. This field supports values like `RuntimeDefault`, `Localhost`, and `Unconfined`, enabling fine-grained control over system call filtering without requiring manual profile loading on the node.

Answer

Seccomp profiles can only be applied to privileged containers

Answer

Seccomp can only restrict system calls, not allow them

Question 13

Which TWO of the following are valid Pod Security Standard levels? (Select 2)

Accepted Answer

privileged. The Pod Security Standards (PSS) define three levels: privileged, baseline, and restricted. The privileged level is the most permissive, allowing known privilege escalations and is intended for system-level workloads that require unrestricted access to host resources. It is explicitly listed in the Kubernetes documentation as one of the three valid PSS levels.

Answer

medium

Answer

high

Answer

default

Question 14

Which of the following is a valid way to drop all capabilities from a container?

Accepted Answer

securityContext:
  capabilities:
    drop: ["ALL"]. In Kubernetes, the `securityContext.capabilities.drop` field is used to explicitly remove Linux capabilities from a container. Dropping `ALL` removes every capability, ensuring the container runs with the least privilege possible, which is a key security best practice for minimizing microservice vulnerabilities.

Answer

securityContext:
  dropCapabilities: true

Answer

securityContext:
  privileged: false

Answer

securityContext:
  capabilities:
    remove: ["ALL"]

Question 15

A pod has been compromised. You want to isolate it from other pods while preserving its network state for forensics. Which NetworkPolicy rule achieves this?

Accepted Answer

Create a NetworkPolicy with podSelector matching the compromised pod and empty ingress/egress rules (deny all). A NetworkPolicy with a `podSelector` matching the compromised pod and empty `ingress` and `egress` rules (i.e., no rules specified) defaults to denying all traffic to and from that pod. This isolates the pod from all other pods in the cluster while preserving its network state for forensics, as the pod remains running and its network interfaces are untouched.

Answer

Deny all ingress and egress traffic to/from the pod's namespace

Answer

Add a label to the pod and create a NetworkPolicy allowing only traffic from a forensic pod

Answer

Delete the pod

Question 16

Which THREE of the following are valid flags for enabling admission plugins on the API server?

Accepted Answer

--enable-admission-plugins=AlwaysPullImages. `--enable-admission-plugins=AlwaysPullImages` is the valid flag to enable the AlwaysPullImages admission plugin on the kube-apiserver. This flag accepts a comma-separated list of plugin names, and AlwaysPullImages is a built-in admission controller that forces every new Pod to pull images again, even if they already exist on the node, enhancing security by ensuring only authorized images are used.

Answer

--plugin-dir=/admission

Answer

--admission-control=NodeRestriction

Question 17

You are configuring an Istio service mesh for mTLS between services. Which resource defines the TLS mode for traffic between services in a namespace?

Accepted Answer

PeerAuthentication. PeerAuthentication is the correct resource because it defines the TLS mode (e.g., STRICT, PERMISSIVE, DISABLE) for mTLS between services within a namespace in Istio. It enforces the authentication policy for workloads, ensuring that all traffic between them uses mutual TLS as specified. This directly controls the TLS mode for inter-service communication at the namespace or mesh level.

Answer

ServiceEntry

Answer

VirtualService

Answer

DestinationRule

Question 18

An admin has deployed a ValidatingWebhookConfiguration that denies pods with `runAsNonRoot: false`. After creating a pod that does not set `runAsNonRoot` at all, the pod is created successfully. Why did the webhook not deny it?

Accepted Answer

The webhook configuration's rules do not match the pod create operation. A is correct because the ValidatingWebhookConfiguration's `rules` define which API operations (e.g., create, update) and resources (e.g., pods) trigger the webhook. If the rules do not include the `create` operation for pods, the webhook will not intercept the pod creation request, so the pod is created without validation. The pod's security context (missing `runAsNonRoot`) is irrelevant if the webhook never fires.

Answer

The webhook's failure policy is set to Ignore

Answer

The webhook is only applied to pods in a specific namespace

Answer

The webhook only applies to pods created with a specific service account

Question 19

Which TWO of the following are recommendations from the CIS Kubernetes Benchmark?

Accepted Answer

Enable audit logging. The CIS Kubernetes Benchmark recommends enabling audit logging to record all API server requests, which is essential for security monitoring and forensic analysis. It also recommends disabling anonymous authentication to ensure that all requests are authenticated, preventing unauthenticated access to the cluster.

Answer

Use TokenReview API for authentication

Answer

Set --protect-kernel-defaults=false on kubelet

Answer

Enable the insecure port for kubelet

Question 20

Which field in a Pod's securityContext prevents privilege escalation by the container?

Accepted Answer

allowPrivilegeEscalation. `allowPrivilegeEscalation` controls whether a process can gain more privileges than its parent process. In a Pod's securityContext, setting this field to `false` prevents the container from performing privilege escalation, such as via setuid binaries or system calls like `setuid(0)`. This directly mitigates a common attack vector where an attacker exploits a container process to gain root access.

Answer

capabilities.add: ["SYS_ADMIN"]

Answer

runAsNonRoot

Answer

privileged