If you are looking for the most important Kubernetes questions which can be asked to you in an interview then you are at the right place where we cover 13 advanced Kubernetes interview questions.

Firstly, before further Q & A discussion we should know the Kubernetes meaning in depth.
kubernetes interview questions

Some Advanced Kubernetes Interview Questions

The word Kubernetes comes from the Greek which means “Captain”. Similar to how the captain oversees the ship’s safe passage across the ocean, Kubernetes is in charge of transporting those boxes to their intended destinations. Docker is not required to use Kubernetes.

Ques 1. In Kubernetes, what are Pod Security Policies (PSPs) and how do they improve security?

Ans 1. To manage the security-related features of pods, including privileged access, Linux capabilities, volume kinds, etc., Kubernetes uses Pod Security Policies (PSPs), which are a set of security rules. By applying these regulations to all pods in a cluster and making sure that each pod complies with a predefined set of security guidelines, PSPs improve security. This minimizes the possibility of errors in configuration or flaws in the pod standards.

Ques 2. Describe the idea of Kubernetes network policies and their applications.

Ans 2. In Kubernetes, network traffic between pods within a cluster can be managed by Network Policies. They provide rules that describe which ports and protocols can be used for communication between different pods. When it’s necessary to implement pod-to-pod communication isolation or segmentation within the cluster, network policies are applied. They increase security by restricting network access based on predefined restrictions.

Ques 3. Compare StatefulSets with Kubernetes Deployments. In what scenario would you select one instead of the other?

Ans 3. Deployments: Kubernetes deployments work well for stateless applications with easily replicable and horizontally scalable instances. They oversee pods and offer features like rollback and rolling updates.

StatefulSets: StatefulSets are used in stateful applications that need long-lasting storage and reliable, distinct network IDs. Regarding the deployment and scaling of pods, they offer guarantees regarding their uniqueness and ordering.

Selecting one out of the two: Use deployments for stateless and horizontally scalable systems, such as web servers, API services, or microservices. For applications that require consistent network identity, permanent storage, and ordered deployment, such as distributed systems like Kafka or Elasticsearch, or databases like MySQL and PostgreSQL, use StatefulSets.

Ques 4. How does Kubernetes’ Horizontal Pod Autoscaling function? Which metrics are appropriate for autoscaling?

Ans 4. The number of pod replicas in a Deployment, ReplicaSet, or StatefulSet is dynamically scaled using Horizontal Pod Autoscaling (HPA) depending on specified metrics or observed CPU utilization. After determining the required number of replicas based on established metrics thresholds, Kubernetes modifies the replica count by submitting a query to the metrics API for the needed metrics.

Auto Scaling metrics in use:

  • CPU utilization: determined by the percentage of CPU resources used.
  • Custom metrics: Using custom metrics APIs (Prometheus, Stackdriver, etc.), one can obtain application-specific metrics such as request rate, queue length, or others.

Ques 5. Explain the secrets management process that Kubernetes uses. Which techniques work best for keeping secrets?

Ans 5. The Secrets API object, which holds private information like SSH keys, OAuth tokens, and passwords, is how Kubernetes handles secrets. Among the best methods for keeping secrets are:

Use of Secrets:

  • Instead of storing sensitive data in pod specs or container images, store it as a Kubernetes secret.
  • Sensitive data should be encrypted both in transit and at rest.
  • Role-Based Access Control (RBAC) in Kubernetes allows you to limit access to secrets.

Rotation: Update apps with new credentials and rotate secrets regularly.

Providers of Secrets: For improved security and lifecycle management, use Kubernetes connectors or third-party secrets management technologies.

Ques 6. In Kubernetes, what are Custom Resource Definitions (CRDs) and why are they beneficial? Describe a real-world application for them.

Ans 6. To extend Kubernetes’ capability beyond pre-built resource types like Pods and Deployments, users can build custom resources and associated schemas using Custom Resource Definitions (CRDs). Complex applications or services that Kubernetes does not natively support can be defined and managed with the help of CRDs.

For example, establishing a CRD for a unique application configuration or a particular kind of workload—such as machine learning jobs with particular resource needs and lifecycle hooks—could be a useful use case. This enables standard operational methods and lifecycle management for Kubernetes to handle these custom resources similarly to native objects.

Ques 7. Describe how Kubernetes Pods use Init Containers. Give examples of situations where using Init Containers is useful.

Ans 7. The answer is that in a pod, initial containers are specialized containers that execute before the main application containers. They are used to initialize databases, configure environment variables, and wait for other services to be available before initiating the main application containers.

Situations when using Init Containers are advantageous:

Database Initialization:

  • Setting up migrations or schemas in the database before launching the main program.
  • Obtaining configuration files from outside sources or secret managers is known as configuration management.
  • Hold off on starting the main application until all dependent services or resources are ready. An example of this would be to wait for a database to become available.

Ques 8. How can Kubernetes Federation make multi-cluster management easier?

Ans 8. Kubernetes Federation offers centralized control and management of applications across clusters by enabling the management of many Kubernetes clusters as a single, cohesive cluster. Facilitating consistent application deployment, scaling, and policy enforcement across geographically dispersed clusters, makes multi-cluster management easier.

Kubernetes Federation features include:

  • The federated clusters’ resources are managed and synchronized by the centralized control plane.
  • Configuration and Policy Maintain uniformity in network policies, resource allocations, and deployment techniques.

Cross-Cluster Service Discovery: This makes it possible to find and use services across federated clusters with ease.

Ques 9. Discuss the idea of Kubernetes Operators. What are their benefits and how do they increase the functioning of Kubernetes?

Ans 9. Kubernetes Operators are a way to use native Kubernetes tools and APIs for packaging, deploying, and controlling a Kubernetes application. By automating difficult application administration processes like provisioning, scaling, and backup/restore procedures, operators increase the capability of Kubernetes.

Benefits of Operators for Kubernetes:

Automation: Based on knowledge particular to an application, automation automates routine operational operations.

Custom Resource Definitions (CRDs):

  • These provide additional specifications for Kubernetes API that are needed to manage intricate applications.
  • Application lifecycle management includes deployment, scalability, and updates.

Self-Healing: Using specified operational information, it keeps an eye on and preserves the health of the application.

Ques 10. Explain the operation of PersistentVolumes (PVs) and PersistentVolumeClaims (PVCs) in the storage management system of Kubernetes.

Ans 10. The ability to abstract and manage storage resources from underlying storage systems is made possible by Kubernetes’ PersistentVolumes (PVs) and PersistentVolumeClaims (PVCs).

Real storage resources that are either dynamically or manually provisioned by an administrator or Kubernetes are represented by persistent volumes (PVs). They do not follow the life cycles of pods and are permanent.

PVCs, or Persistent Volume Claims, are used to request storage resources. They serve as a user’s or a pod’s request for storage. PVs and PVCs bind according to compatible criteria like storage class and access modes.

Ques 11. What does Kubernetes’ PodDisruptionBudget mean, and why is it important? What is it, and how is it used?

Ans 11. To limit the number of pods that can be down at once during voluntary disruptions (such as rolling updates or node maintenance), Kubernetes has a resource called PodDisruptionBudget (PDB). It lowers the possibility of application downtime by guaranteeing high availability and preventing a service’s pods from going down at the same time.

Usage: YAML manifests are used to define PDB, which indicates:

MinAvailable: The bare minimum of pods that have to be on hand.

MaximumUnavailable:

  • The highest quantity or proportion of pods that are not available.
  • PDBs are used to manage the disruption budget during scaling or maintenance operations for deployments, stateful sets, or replica sets.

Ques 12. Describe the variations between StatefulSet, Deployment, and DaemonSet in Kubernetes. Which would you use when?

Ans 12. Kubernetes Controller

1. Deployment:

A Deployment is a controller that controls a collection of identical, stateless pods. It allows declarative updates to applications, allowing you to declare the desired state of your application and automate the change rollout.
Key features:
Rolling Updates: Allows for the gradual replacement of old pods with new ones, resulting in zero downtime.
Rollback: Allows you to return to a prior version if necessary.
Scaling: You may easily increase or decrease the number of replicas.
Use Case: Ideal for stateless apps that do not require persistent storage or unique network identities. Examples include web servers, API services, and microservices.

2. StatefulSet:

Definition: A StatefulSet is a controller that manages stateful applications. Unlike Deployments, StatefulSets guarantee the sequence and uniqueness of pods.
Key features:
Stable Network Identity: Each pod has a distinct, persistent network identity (e.g., pod-0, pod-1) that remains constant throughout rescheduling.
Stable Storage: Manages persistent volumes for each pod, ensuring that storage remains intact even if the pod is rescheduled.
Ordered Deployment: Pods are generated, updated, and destroyed in a specified order.
Use Case: Suitable for applications that require reliable network identities and persistent storage, such as databases, distributed systems, and state-preserving applications. Examples include Cassandra, MongoDB, and Zookeeper.

3. DaemonSet:

Definition: A DaemonSet ensures that a pod is replicated on all (or some) nodes in a cluster. It is used to deploy system-level services or monitoring agents, which must be present on all nodes.
Key features:
Node Coverage: Pods are scheduled on all or a subset of nodes based on predefined parameters.
Automatic Updates: When nodes are added or withdrawn, the DaemonSet updates the number of pods accordingly.
Use Case: This is ideal for deploying services that must run on all nodes, such as log collectors, monitoring agents (like Prometheus Node Exporter), or system daemons.

Ques 13. How is container networking handled by Kubernetes? Talk about the many networking options that Kubernetes offers.

Ans 13. The Container Network Interface (CNI), with which plugins interface to offer networking features, is how Kubernetes overseas container networking.

Numerous networking solutions are supported by Kubernetes:

  • Virtual networks superimposed on real networks to allow pods to communicate with each other across nodes are known as overlay networks (e.g., Flannel, Calico).

Service Proxy:

  • Using kube-proxy, the Kubernetes Service abstraction offers a standardized method of accessing pods wherever they may be.

Network regulations:

  • Permit the establishment of guidelines for pod-to-pod communication inside the cluster, managing traffic entering and leaving the system in accordance with predefined regulations (e.g., Calico Network Policies).
  • Different functionality and performance characteristics are offered by each Kubernetes networking solution to meet different deployment scenarios and needs.

Conclusion

Hence, we are concluding this blog here. Hope we have provided all the 13 Advanced Kubernetes questions important for the interview. Read all these questions and answers carefully and give some crystals to your Kubernetes interview questions preparation journey.