1000+ Devops Engineer Interview Questions and Answers

When an instance in AWS is deregistered, the load balancer stops sending traffic to that instance.

• The load balancer detects the deregistration of the instance and stops routing traffic to it.

• The load balancer redistributes the traffic to the remaining healthy instances.

• The deregistered instance is no longer considered part of the load balancer's target group.

• The load balancer health checks will mark the instance as unhealthy.

• The load balancer will not send any new requests to...read more

Setting up distributed Jenkins nodes is necessary for scaling Jenkins infrastructure and improving performance.

• When there is a need to run a large number of jobs simultaneously

• When jobs require different environments or configurations

• When jobs need to be executed on different platforms or operating systems

• When there is a need for high availability and fault tolerance

• When there is a need to reduce build queue times and improve overall performance

Key elements in continuous testing tools include automation, integration with CI/CD pipelines, reporting and analytics, scalability, and support for various testing types.

• Automation of test cases to ensure quick feedback on code changes

• Integration with CI/CD pipelines for seamless testing in the software delivery process

• Reporting and analytics capabilities to track test results and identify issues

• Scalability to handle testing across different environments and configurations

• Su...read more

The lifecycle of a Docker container involves creation, running, pausing, restarting, and stopping.

• 1. Creation: A Docker container is created from a Docker image using the 'docker run' command.

• 2. Running: The container is started and runs the specified application or service.

• 3. Pausing: The container can be paused using the 'docker pause' command, which temporarily stops its processes.

• 4. Restarting: The container can be restarted using the 'docker restart' command.

• 5. Stopping:...read more

git revert undoes a specific commit by creating a new commit, while git reset moves the HEAD to a previous commit without creating a new commit.

• git revert creates a new commit that undoes a specific commit, keeping the commit history intact

• git reset moves the HEAD to a previous commit, potentially discarding changes made after that commit

• git revert is safer for shared branches as it does not rewrite history, while git reset can be used for local branches to reset to a previou...read more

Clusters creation involves setting up multiple servers to work together, while handling practical bugs requires troubleshooting and fixing issues in the cluster.

• Clusters creation involves setting up multiple servers to work together to distribute workload and increase reliability.

• Tools like Kubernetes or Docker Swarm can be used to create and manage clusters efficiently.

• Practical bugs in clusters can include network issues, configuration errors, or software compatibility prob...read more

Inode number is a unique identifier for a file in a filesystem, while a file descriptor is a reference to an open file.

• Inode number is a metadata associated with a file, stored in the filesystem's inode table.

• File descriptor is a reference to an open file in a process, represented by an integer.

• Inode number remains constant for a file even if it is moved or renamed, while file descriptor changes with each open/close operation.

• Example: In a Unix-like system, 'ls -i' command di...read more

Transit Gateway is a network transit hub that enables interconnectivity between virtual private clouds (VPCs) and on-premises networks.

• Transit Gateway simplifies network architecture by allowing multiple VPCs and VPN connections to connect to a single gateway.

• It provides a hub-and-spoke model for connecting VPCs and on-premises networks.

• Transit Gateway also supports routing between VPCs and on-premises networks, and can be used to consolidate VPC peering connections.

• It can al...read more

A virtual private cloud (VPC) or Vnet is a private network in the cloud that allows you to isolate resources and control network traffic.

• VPC/Vnet provides a secure and isolated environment for resources in the cloud.

• It allows you to define your own IP address range, subnets, route tables, and network gateways.

• VPC/Vnet helps in creating a secure connection between on-premises data centers and cloud resources.

• It is used in DevOps to ensure secure communication between different...read more

Ingress is a layer 7 HTTP routing mechanism while Load Balancer is a layer 4 TCP/UDP load balancer in Kubernetes.

• Ingress is used to expose HTTP and HTTPS routes to services inside the cluster, while Load Balancer is used to distribute traffic across multiple nodes.

• Ingress provides features like SSL termination, path-based routing, and name-based virtual hosting, while Load Balancer focuses on distributing traffic based on IP and port.

• Ingress is a resource that manages externa...read more

To host a web application on AWS, use services like EC2, S3, and RDS, and manage them with Terraform.

• Use Amazon EC2 for hosting the web server (e.g., Apache, Nginx).

• Utilize Amazon S3 for static file storage (e.g., images, CSS).

• Implement Amazon RDS for database management (e.g., MySQL, PostgreSQL).

• Consider using AWS Elastic Load Balancer for distributing traffic.

• Use AWS Route 53 for domain name management and DNS routing.

You can kill all Java processes with a single command using pkill or killall commands.

• Use pkill command followed by the process name 'java' to kill all Java processes: pkill java

• Alternatively, you can use killall command with the process name 'java' to achieve the same result: killall java

Amazon ECS is a container management service while Amazon EKS is a managed Kubernetes service.

• Amazon ECS is a fully managed container orchestration service, while Amazon EKS is a managed Kubernetes service.

• Amazon ECS is more tightly integrated with other AWS services like CloudWatch, IAM, and VPC, while Amazon EKS is more flexible and can run on any cloud provider.

• Amazon ECS uses its own proprietary orchestration engine, while Amazon EKS uses Kubernetes for container orchestr...read more

Monitoring a Kubernetes cluster involves using tools like Prometheus, Grafana, and Kubernetes Dashboard.

• Use Prometheus for collecting metrics from Kubernetes components and applications running on the cluster.

• Set up Grafana for visualizing the collected metrics and creating dashboards for monitoring.

• Utilize Kubernetes Dashboard for a graphical interface to view and manage the cluster resources.

• Implement alerts and notifications using tools like Prometheus Alertmanager to proa...read more

To secure and harden Tomcat, several precautions can be taken.

• Disable unused connectors and ports

• Use SSL/TLS encryption for secure communication

• Implement access control and authentication mechanisms

• Regularly update Tomcat and its dependencies

• Configure logging and monitoring for security events

Yes, I can write an Ansible playbook to install Apache.

• Use the 'apt' module to install Apache on Debian/Ubuntu systems

• Use the 'yum' module to install Apache on Red Hat/CentOS systems

• Ensure to start and enable the Apache service after installation

DevOps is a culture that promotes collaboration between development and operations teams to deliver software faster and more reliably.

• DevOps helps organizations to achieve faster time-to-market, improved quality, and increased efficiency.

• It involves automating the software delivery process, continuous integration and deployment, and monitoring and feedback loops.

• DevOps also emphasizes on communication, collaboration, and shared responsibility between teams.

• Examples of DevOps ...read more

To debug issues with Apache and Nginx, check error logs, configuration files, server status, and network connectivity.

• Check error logs for any relevant error messages or warnings.

• Review configuration files for any misconfigurations or typos.

• Check server status to ensure services are running and responding correctly.

• Verify network connectivity to ensure there are no network issues affecting communication.

• Use tools like curl, telnet, or netcat to test connections and troublesho...read more

Running Docker inside Docker is useful for testing, CI/CD pipelines, and isolating environments.

• Testing different Docker configurations

• Running CI/CD pipelines within containers

• Isolating development environments

• Building and testing Docker images within containers

To ensure high availability of the etcd cluster used by Kubernetes, you can implement redundancy, monitoring, and disaster recovery strategies.

• Implement a multi-node etcd cluster to ensure redundancy and fault tolerance.

• Utilize monitoring tools like Prometheus and Grafana to track the health and performance of the etcd cluster.

• Set up regular backups and implement disaster recovery plans to quickly recover from failures.

• Use Kubernetes features like PodDisruptionBudgets to prev...read more

Yes, I faced challenges while creating the DevOps pipeline.

• One challenge was integrating multiple tools and technologies into the pipeline.

• Another challenge was ensuring smooth communication and collaboration between different teams involved in the pipeline.

• I also faced challenges in automating the testing and deployment processes to achieve continuous integration and continuous delivery.

• Dealing with legacy systems and transitioning them into the new pipeline was also a chall...read more

Jenkins is an open-source automation server that helps to automate the non-human part of the software development process.

• Jenkins is a Java-based application that runs in a servlet container like Apache Tomcat.

• It can be installed on a single server or distributed across multiple servers for scalability.

• Jenkins uses plugins to extend its functionality, allowing integration with various tools and technologies.

• It follows a master-slave architecture where the master node manages ...read more

To troubleshoot EC2 not having access to me, check security groups, network ACLs, and routing tables.

• Check if the EC2 instance is in the correct security group

• Verify that the security group allows inbound traffic from your IP address or CIDR block

• Check if there are any network ACLs that may be blocking traffic

• Verify that the routing table is correctly configured

• Check if there are any firewall rules on your local machine that may be blocking traffic

• Use tools like ping, tracero...read more

To debug a progressively slowing down website, I would analyze the server logs, check for memory leaks, and optimize the code.

• Analyze server logs to identify any errors or bottlenecks

• Check for memory leaks in the code

• Optimize the code by removing unnecessary scripts and optimizing images

• Use tools like Chrome DevTools to identify performance issues

• Consider implementing a content delivery network (CDN) to improve website speed

Chef is a configuration management tool used in DevOps to automate infrastructure deployment and management.

• Automating server configuration and management

• Ensuring consistency across environments

• Enabling infrastructure as code practices

• Automating application deployment processes

• Managing complex infrastructure at scale

Yes, I have written Docker files from scratch. The syntax for Docker file includes instructions and arguments.

• Docker file is a script that contains instructions to build a Docker image

• The syntax includes instructions like FROM, RUN, COPY, CMD, etc.

• Arguments are used to specify details like the base image, working directory, etc.

• Example: FROM ubuntu:latest RUN apt-get update && apt-get install -y python3

• Example: COPY . /app WORKDIR /app CMD python3 app.py

Docker file structure for nginx image and resolving Git conflicts

• Dockerfile structure for nginx image: FROM nginx, COPY index.html /usr/share/nginx/html, EXPOSE 80

• To resolve Git conflicts: git status, git pull, git add , git commit -m 'Resolved conflict', git push