Quiz Module 4 - Services and Networking

Instructions

This quiz contains 30 multiple-choice questions to validate your understanding of Module 4.

Tip: Answer each question before revealing the answer.

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Question 1

What is the main role of a Service in Kubernetes?

1. Manage the lifecycle of Pods

2. Expose a set of Pods as a network service with a stable IP

3. Store persistent data

4. Manage secrets

Show explanation

Correct answer: Expose a set of Pods as a network service with a stable IP

Explanation: A Service provides a stable IP and DNS name to access a group of Pods, even if the Pod IPs change.

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Question 2

Which Service type is used by default and is only accessible from within the cluster?

1. ClusterIP

2. NodePort

3. LoadBalancer

4. ExternalName

Show explanation

Correct answer: ClusterIP

Explanation: ClusterIP is the default type. It exposes the Service on an internal cluster IP, accessible only from within the cluster.

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Question 3

Which Service type exposes the application on a static port on each node?

1. ClusterIP

2. NodePort

3. LoadBalancer

4. ExternalName

Show explanation

Correct answer: NodePort

Explanation: NodePort exposes the Service on a static port (30000-32767) on each node, allowing access to the Service from outside the cluster via [NodeIP]:[NodePort].

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Question 4

Which Service type automatically creates an external load balancer in cloud environments?

1. ClusterIP

2. NodePort

3. LoadBalancer

4. ExternalName

Show explanation

Correct answer: LoadBalancer

Explanation: LoadBalancer extends NodePort and automatically creates an external load balancer in cloud environments (AWS ELB, Azure Load Balancer, GCP Load Balancer).

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Question 5

What is the DNS format of a Service in Kubernetes?

1. [service-name]

2. [service-name].[namespace].svc.cluster.local

3. [service-name].[namespace]

4. [service-name].cluster.local

Show explanation

Correct answer: [service-name].[namespace].svc.cluster.local

Explanation: Services have a fully qualified DNS name that includes the Service name, the namespace, and the cluster domain, enabling DNS resolution across the entire cluster.

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Question 6

Which Kubernetes component handles DNS resolution for Services?

1. kube-proxy

2. CoreDNS

3. kubelet

4. API Server

Show explanation

Correct answer: CoreDNS

Explanation: CoreDNS is the DNS service that resolves Service names and enables service discovery via DNS within the cluster.

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Question 7

What is an Endpoint in Kubernetes?

1. A type of Service

2. A resource that lists the IP addresses of Pods matching a Service's selectors

3. A network entry point

4. A type of Pod

Show explanation

Correct answer: A resource that lists the IP addresses of Pods matching a Service's selectors

Explanation: Endpoints are automatically created for each Service and contain the IP addresses of the backend Pods that match the Service's selectors.

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Question 8

What is an EndpointSlice?

1. A type of Service

2. An improved version of Endpoint that manages large numbers of backends more efficiently

3. A type of Pod

4. A type of volume

Show explanation

Correct answer: An improved version of Endpoint that manages large numbers of backends more efficiently

Explanation: EndpointSlice is a modern alternative to Endpoint that splits endpoints into multiple slices, improving performance for Services with many backends.

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Question 9

What is the default load balancing mode for a ClusterIP Service?

1. Round-robin only

2. Round-robin via iptables or IPVS (depending on kube-proxy configuration)

3. Least connections

4. Random

Show explanation

Correct answer: Round-robin via iptables or IPVS (depending on kube-proxy configuration)

Explanation: kube-proxy uses iptables (default) or IPVS to distribute traffic among backend Pods in a round-robin fashion.

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Question 10

What is a headless Service?

1. A Service without Pods

2. A Service with clusterIP: None that directly returns Pod IPs

3. A Service without an IP

4. A deprecated Service

Show explanation

Correct answer: A Service with clusterIP: None that directly returns Pod IPs

Explanation: A headless Service (clusterIP: None) allows you to directly obtain Pod IP addresses via DNS, useful for StatefulSets and service discovery.

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Question 11

What is a Network Policy?

1. A routing policy

2. A resource that defines network communication rules between Pods

3. A Service policy

4. A DNS configuration

Show explanation

Correct answer: A resource that defines network communication rules between Pods

Explanation: Network Policies allow you to control network traffic between Pods, acting as a firewall at the cluster level.

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Question 12

Which CNI plugin is required to use Network Policies?

1. Flannel

2. A CNI plugin that supports Network Policies (Calico, Cilium, Weave, etc.)

3. CoreDNS

4. kube-proxy

Show explanation

Correct answer: A CNI plugin that supports Network Policies (Calico, Cilium, Weave, etc.)

Explanation: Not all CNI plugins support Network Policies. You must use a compatible plugin such as Calico, Cilium, or Weave.

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Question 13

What is the default port of a Service if not specified?

1. 80

2. The port must be explicitly specified

3. 443

4. 8080

Show explanation

Correct answer: The port must be explicitly specified

Explanation: Kubernetes does not define a default port for Services. The port must be specified in the Service definition.

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Question 14

What is an ExternalName Service?

1. An external Service

2. A Service that maps a Service to an external DNS name

3. A Service without an IP

4. A headless Service

Show explanation

Correct answer: A Service that maps a Service to an external DNS name

Explanation: ExternalName maps a Kubernetes Service to an external DNS name, allowing access to external services as if they were internal to the cluster.

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Question 15

What is the port range for NodePort?

1. 1-65535

2. 30000-32767

3. 1024-65535

4. 20000-30000

Show explanation

Correct answer: 30000-32767

Explanation: NodePort ports are assigned in the 30000-32767 range by default, although this range can be configured.

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Question 16

What is sessionAffinity in a Service?

1. A load balancing method

2. A configuration that ensures requests from a client always go to the same backend Pod

3. A security policy

4. A DNS configuration

Show explanation

Correct answer: A configuration that ensures requests from a client always go to the same backend Pod

Explanation: sessionAffinity: ClientIP ensures that all requests from the same client IP are directed to the same backend Pod, useful for sessions.

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Question 17

What is the role of kube-proxy in Kubernetes networking?

1. Resolve DNS names

2. Maintain network rules (iptables/IPVS) for Services and perform load balancing

3. Manage Pods

4. Schedule Pods

Show explanation

Correct answer: Maintain network rules (iptables/IPVS) for Services and perform load balancing

Explanation: kube-proxy watches Services and Endpoints, and updates iptables or IPVS rules to direct traffic to the appropriate backend Pods.

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Question 18

What is a Service without a selector?

1. A headless Service

2. A Service that points to manually defined external endpoints

3. A deprecated Service

4. A Service without Pods

Show explanation

Correct answer: A Service that points to manually defined external endpoints

Explanation: A Service without a selector allows you to create a Service that points to external endpoints by manually creating an Endpoints object.

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Question 19

What is the advantage of using IPVS instead of iptables for kube-proxy?

1. IPVS is simpler

2. IPVS offers better performance and more load balancing options for many Services

3. IPVS is more secure

4. IPVS is easier to configure

Show explanation

Correct answer: IPVS offers better performance and more load balancing options for many Services

Explanation: IPVS uses hash tables instead of long iptables chains, offering better performance and more load balancing algorithms (rr, lc, dh, sh, sed, nq).

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Question 20

What is cluster.local in Kubernetes DNS?

1. A namespace

2. The default DNS domain of the cluster

3. A Service

4. A type of Pod

Show explanation

Correct answer: The default DNS domain of the cluster

Explanation: cluster.local is the default DNS domain used by CoreDNS to resolve Service names in the cluster (can be configured differently).

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Question 21

What is the difference between a ClusterIP Service and a NodePort Service?

1. No difference

2. ClusterIP is only accessible within the cluster, NodePort also exposes a port on each node

3. NodePort is internal only

4. ClusterIP is external

Show explanation

Correct answer: ClusterIP is only accessible within the cluster, NodePort also exposes a port on each node

Explanation: A ClusterIP Service is only accessible from within the cluster, while a NodePort extends ClusterIP by also exposing a static port on each node.

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Question 22

What is a Service Account in the context of networking?

1. A network account

2. A type of Service

3. An identity for Pods, used for authentication with the API Server

4. A DNS account

Show explanation

Correct answer: An identity for Pods, used for authentication with the API Server

Explanation: A Service Account provides an identity for Pods, enabling authentication and authorization when accessing the API Server, but is not directly related to Service networking.

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Question 23

What is the role of an Ingress in Kubernetes?

1. Manage Services

2. Expose HTTP/HTTPS Services from outside the cluster with path-based or hostname-based routing

3. Manage DNS

4. Manage Pods

Show explanation

Correct answer: Expose HTTP/HTTPS Services from outside the cluster with path-based or hostname-based routing

Explanation: Ingress allows you to expose multiple Services through a single entry point with routing based on URL path or hostname, with TLS/SSL support.

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Question 24

What is a CNI plugin?

1. A type of Service

2. A network plugin that configures Pod networking in Kubernetes

3. A type of Pod

4. A Control Plane component

Show explanation

Correct answer: A network plugin that configures Pod networking in Kubernetes

Explanation: CNI (Container Network Interface) is a standard interface that allows network plugins (Calico, Flannel, Weave, etc.) to configure Pod networking.

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Question 25

What is the command to view the Endpoints of a Service?

1. kubectl get services

2. kubectl get endpoints

3. kubectl get pods

4. kubectl get network

Show explanation

Correct answer: kubectl get endpoints

Explanation: This command displays Endpoints that list the IP addresses of backend Pods for each Service.

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Question 26

What is a Service mesh?

1. A type of Service

2. A dedicated infrastructure that manages communication between microservices with observability, security, and traffic control

3. A CNI plugin

4. A type of Pod

Show explanation

Correct answer: A dedicated infrastructure that manages communication between microservices with observability, security, and traffic control

Explanation: A Service mesh (like Istio, Linkerd) adds a networking layer that manages communication between services with advanced features like mTLS, circuit breaking, and observability.

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Question 27

What is the difference between a Service and an Ingress?

1. No difference

2. A Service exposes a set of Pods, an Ingress exposes HTTP/HTTPS Services with advanced routing

3. Ingress is a type of Service

4. Service is a type of Ingress

Show explanation

Correct answer: A Service exposes a set of Pods, an Ingress exposes HTTP/HTTPS Services with advanced routing

Explanation: A Service exposes Pods with a stable IP and load balancing. An Ingress is a layer on top that enables HTTP/HTTPS routing based on path or hostname to multiple Services.

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Question 28

What is an ExternalIP in a Service?

1. An IP external to the cluster

2. An external IP address that can be used to access the Service from outside the cluster

3. A Pod IP

4. A node IP

Show explanation

Correct answer: An external IP address that can be used to access the Service from outside the cluster

Explanation: externalIPs allows you to specify external IP addresses that will be routed to the Service, enabling external access without a LoadBalancer.

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Question 29

What is the command to test DNS resolution of a Service?

1. kubectl get dns

2. nslookup [service-name].[namespace].svc.cluster.local from within a Pod

3. kubectl resolve [service-name]

4. kubectl dns [service-name]

Show explanation

Correct answer: nslookup [service-name].[namespace].svc.cluster.local from within a Pod

Explanation: You can test DNS resolution by running nslookup or dig from within a Pod to verify that CoreDNS correctly resolves the Service name.

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Question 30

What is a Service without a specified targetPort?

1. The Service does not work

2. The targetPort uses the same value as the port

3. The Service uses port 80

4. The Service uses port 443

Show explanation

Correct answer: The targetPort uses the same value as the port

Explanation: If targetPort is not specified in a Service, it uses the same value as the port, meaning traffic to the Service port is directed to the same port on the backend Pods.

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Quiz Results

Congratulations on completing the Module 4 quiz!

Score:

• 25-30 correct answers: Excellent!
• 20-24 correct answers: Very good!
• 15-19 correct answers: Good!
• Less than 15: Recommended to review the module.

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Quiz created: December 2024