AWS Cloud

AWS Cloud Interview Questions Every Engineer Should Practice

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AWS Cloud Interview Questions Every Engineer Should Practice Beginner-Level Questions Icon-Architecture/64/Arch_AWS-Serverless-Application-Repository_64Created with Sketch. AWS General 1. What is AWS?AWS (Amazon Web Services) is a cloud computing platform that offers on-demand computing resources and services such as storage, databases, networking, and more. 2. What are the benefits of using AWS?Benefits include scalability, cost efficiency, flexibility, security, and high availability. 3. What types of cloud computing models does AWS offer?The models include Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS). 4. What is an AWS Region?A region is a specific geographical area that contains multiple AWS data centers (availability zones). Each region operates independently and provides services closer to users for reduced latency. 5. What is an Availability Zone?An Availability Zone (AZ) is a physical data center located within an AWS Region. Each region has multiple AZs to ensure fault tolerance. Icon-Architecture/64/Arch_Amazon-EC2_64Created with Sketch. EC2 (Elastic Compute Cloud) 1. What is EC2 in AWS?EC2 is a web service that offers resizable compute capacity in the cloud, enabling users to launch and manage virtual machines (instances). 2. What are the different types of EC2 instances?Instance types include General Purpose (e.g., t2, t3), Compute Optimized (e.g., c5), Memory Optimized (e.g., r5), Storage Optimized (e.g., i3), and GPU Instances (e.g., p3). 3. How do you launch an EC2 instance?You can launch an instance through the AWS Management Console, AWS CLI, or AWS SDKs by selecting an AMI, instance type, and security settings. 4. What is an AMI (Amazon Machine Image)?An AMI is a pre-configured template that contains the operating system, application server, and applications necessary to launch an EC2 instance. 5. What are EC2 key pairs?Key pairs are used for secure login to EC2 instances, consisting of a public key (stored in AWS) and a private key (kept by the user). Icon-Architecture/64/Arch_Amazon-Simple-Storage-Service_64 S3 (Simple Storage Service) 1. What is Amazon S3?Amazon S3 is an object storage service that saves data as objects within buckets, providing high availability, scalability, and durability. 2. What are the storage classes in S3?The storage classes include Standard, Intelligent-Tiering, Standard-IA, One Zone-IA, Glacier, and Glacier Deep Archive. 3. How does versioning work in S3?S3 versioning allows multiple versions of an object to be stored in a bucket, protecting against accidental overwrites or deletions. 4. What is an S3 bucket?A bucket is a container used to store objects (files) in Amazon S3, with each bucket having a unique name. 5. What are S3 access control policies?S3 uses Bucket Policies and ACLs (Access Control Lists) to manage access to buckets and objects. Icon-Architecture/64/Arch_Amazon-RDS_64Created with Sketch. RDS (Relational Database Service) 1. What is Amazon RDS?RDS is a managed database service that supports relational databases like MySQL, PostgreSQL, Oracle, SQL Server, and Amazon Aurora. 2. How do you ensure high availability in RDS?RDS Multi-AZ deployment enhances availability by automatically replicating data to a standby instance in another AZ. 3. What is Amazon Aurora?Amazon Aurora is a high-performance relational database engine compatible with MySQL and PostgreSQL, designed for cloud scalability and availability. 4. How does automated backup work in RDS?RDS conducts daily automatic backups and retains transaction logs, facilitating point-in-time recovery. 5. What is the difference between RDS and DynamoDB?RDS is for relational databases (SQL-based), while DynamoDB is a NoSQL database service designed for high throughput. Intermediate-Level Questions Icon-Architecture/64/Arch_Amazon-EC2_64Created with Sketch. EC2 (Elastic Compute Cloud) 1. What are the EC2 instance types based on workload? Instance types include General Purpose (e.g., t3, m5), Compute Optimized (e.g., c5), Memory Optimized (e.g., r5), and Storage Optimized (e.g., i3). 2. What are Spot Instances? Spot Instances are unused EC2 instances available at discounted rates, which can be interrupted by AWS with little notice. 3. What is Auto Scaling in AWS EC2? Auto Scaling automatically adjusts the number of EC2 instances based on demand to sustain application performance and cost efficiency. 4. What is an Elastic IP in AWS? An Elastic IP is a static, public IP address that can be linked to any instance or network interface in a VPC. 5. How do you stop and start an EC2 instance without losing data? Stopping an instance shuts it down while preserving the attached EBS volumes. However, data on the instance store (ephemeral storage) will be lost. Icon-Architecture/64/Arch_Amazon-Simple-Storage-Service_64 S3 (Simple Storage Service) 1. What is S3 lifecycle management? Lifecycle management automates the transition of objects between storage classes or deletes them after a defined period. 2. What is S3 Cross-Region Replication (CRR)? CRR automatically replicates objects in an S3 bucket to another bucket in a different AWS Region for disaster recovery or low-latency access. 3. How can you make S3 objects publicly accessible? By configuring S3 bucket policies, ACLs, or enabling public read permissions for the objects. 4. What is S3 Transfer Acceleration? This feature accelerates file uploads to S3 by utilizing Amazon CloudFront’s globally distributed edge locations. 5. How is encryption managed in S3? S3 supports server-side encryption (SSE) using S3-managed keys (SSE-S3), KMS-managed keys (SSE-KMS), and customer-provided keys (SSE-C). Icon-Architecture/64/Arch_AWS-Single-Sign-On_64Created with Sketch. IAM (Identity and Access Management) 1. What is AWS IAM? IAM is a service that enables users to securely control access to AWS resources through policies, roles, and user accounts. 2. What is an IAM policy? An IAM policy specifies permissions for actions on AWS resources and is attached to users, groups, or roles to manage access. 3. What is an IAM role? A role is an AWS identity with permission policies that can be assumed by entities like users, applications, or services. 4. How do you implement multi-factor authentication (MFA) in AWS? MFA adds an extra security layer by requiring users to input a one-time password in addition to their regular credentials. 5. What distinguishes an IAM user from a role? An IAM user is an AWS identity linked to login credentials, while a role is designed for granting temporary access to AWS resources. Advanced-Level Questions Icon-Architecture/64/Arch_AWS-Lambda_64Created with Sketch. Lambda (Serverless Computing) 1. What is AWS Lambda?AWS Lambda is a serverless compute service that executes code

Deep Dive into AWS S3 Storage Classes: Choose the Right Tier for Every Use Case

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Deep Dive into AWS S3 Storage Classes: Choose the Right Tier for Every Use Case Amazon S3 (Simple Storage Service) is one of the most reliable and flexible cloud storage solutions. But with multiple storage classes available—each designed for different access patterns, performance needs, and cost considerations—it’s crucial to understand which class best fits your data. In this post, we’ll break down every S3 storage class with an easy-to-read comparison table, summarize them by category, walk through real-world examples, and end with hands-on interview-style questions to test your understanding. AWS S3 Storage Classes Comparison Table Storage Class Durability Availability Availability Zone (AZ) Scope Region-Level Redundancy Minimum Storage Duration Retrieval Time Access Frequency Storage Cost Retrieval Cost Use Cases Key Features / Notes S3 Standard 99.999999999% (11 9’s) 99.99% Data stored across ≥3 AZs Fully replicated within region None Milliseconds Frequent Highest None Frequently accessed data, websites, mobile apps Default class, high performance, Multi-AZ fault tolerance S3 Intelligent-Tiering 99.999999999% 99.9% Multi-AZ replication (same as Standard) Regional replication 30 days (per tier) Milliseconds Variable / Unpredictable Dynamic (tier-based) Yes (for infrequent tiers) Unpredictable access patterns Auto-cost optimization across multiple access tiers S3 Standard-IA (Infrequent Access) 99.999999999% 99.9% Multi-AZ (≥3) Regional replication 30 days Milliseconds Infrequent Lower than Standard Yes Long-term storage for infrequently accessed data Lower storage cost than Standard; retrieval cost applies S3 One Zone-IA 99.999999999% 99.5% Single AZ only No regional replication 30 days Milliseconds Infrequent Lower than Standard-IA Yes Re-creatable or non-critical data Not effective for fault-tolerant (no AZ redundancy) S3 Glacier Instant Retrieval 99.999999999% 99.9% Multi-AZ (≥3) Regional replication 90 days Milliseconds Rare (but needs fast access) Very Low Moderate Medical archives, media archives Archive objects with milliseconds access time S3 Glacier Flexible Retrieval (formerly S3 Glacier) 99.999999999% 99.99% Multi-AZ (≥3) Regional replication 90 days 1–12 hours (based on retrieval type) Rare Very Low Varies by retrieval speed Backup archives, data compliance Cost-effective for archive with flexible retrieval speed S3 Glacier Deep Archive 99.999999999% 99.99% Multi-AZ (≥3) Regional replication 180 days 12–48 hours Very Rare Lowest Highest Long-term retention, legal archives Cheapest storage class; intended for long-term archive data S3 Reduced Redundancy (Deprecated) 99.99% 99.99% Fewer AZs (2 typically) Limited redundancy None Milliseconds Frequent Deprecated None Non-critical, reproducible data Not recommended; replaced by One Zone-IA Quick Summary by Category Category Classes Summary Frequent Access S3 Standard Best for day-to-day apps and dynamic data. Intelligent Access Optimization S3 Intelligent-Tiering Best for unpredictable workloads (auto cost optimization). Infrequent Access S3 Standard-IA, One Zone-IA Best for backups or rarely accessed but important data. Archival Storage Glacier Instant, Glacier Flexible, Glacier Deep Archive Best for long-term data retention with various retrieval speeds. Real-World Usage Scenarios Scenario Recommended Class Reason Hosting a static website S3 Standard Needs high availability and low latency. Storing ML training datasets accessed monthly S3 Standard-IA Accessed infrequently but still needed fast when required. Backup data that can be regenerated S3 One Zone-IA Cost-effective since AZ redundancy not needed. Storing compliance documents for 7 years S3 Glacier Deep Archive Extremely low-cost long-term archival. Data with unpredictable access (some hot, some cold) S3 Intelligent-Tiering Automatically optimizes cost based on access pattern. Legacy database backups needing quick retrieval S3 Glacier Instant Retrieval Archived but immediately accessible. Cost Optimization Strategy To maximize efficiency, implement a multi-tier S3 lifecycle policy. This automates data transitions between classes: S3 Standard → Intelligent-Tiering → Standard-IA → Glacier → Deep Archive You can also set policies to delete expired or unnecessary objects automatically. This approach ensures optimal cost-efficiency while maintaining 11 nines of durability. Final Thoughts AWS S3 storage classes are not “one-size-fits-all.” By aligning data access frequency, retrieval urgency, and cost constraints, you can achieve maximum performance and savings. For modern cloud architectures—especially data lakes, machine learning pipelines, and compliance storage—understanding these tiers is key to efficient design. https://srtechops.com/wp-content/uploads/2025/01/Remainder-App-Technology-Logo.mp4 Devops Multi cloud Training Choose the training style that fits your schedule — Self-Paced or Live Interactive Sessions. Both include hands-on projects, expert support, and lifetime access. Feature Self-Paced Training Live Training 🎯 Mode 🎥Pre-Recorded Session 🧑‍🏫Live Class + Recordings 💼 Projects 🕒 Weekend Real-Time Projects 📅 Weekdays + Weekend Real-Time Projects ❓ Doubt Clearing 📞 Weekend Live Support Session 🧠 Anytime Doubt Clearing Session 👥 Career Support & Mentorship ❌ No ✅ Yes 🎓 Global Certification Training ❌ No ✅ Yes 🔑 Access ♾️ Lifetime Access ♾️ Lifetime Access 💰 Fees ₹4,999 (2 x ₹2,500) ₹7,999 (2 x ₹4,000) ℹ️ For More Info Explore Self-Paced Training Explore Live Training

Deploy a Java Web App to Remote Tomcat Using Jenkins + Maven | AWS EC2 Setup

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🚀 Deploy a Java Web App to Remote Tomcat Using Jenkins + Maven | AWS EC2 Setup 🧰 Overview In a real-world CI/CD setup, Jenkins and Tomcat often run on different servers. This guide shows how to: ✅ Set up Jenkins on one EC2 instance✅ Install and configure Tomcat on a separate EC2 instance✅ Deploy a Java WAR file using Maven and Jenkins✅ Automatically trigger builds using Poll SCM every minute 🏗️ Architecture Diagram [Jenkins EC2 Instance] ──deploys WAR──▶ [Tomcat EC2 Instance]                       │                                                                                  │                       └─── Polls Git Repo every minute  ───┘ ✅ Prerequisites Two EC2 instances on AWS (Amazon Linux or Ubuntu) Jenkins installed on one EC2 instance Tomcat installed on another EC2 instance Maven installed on Jenkins EC2 A sample Java project using Maven (pom.xml) Git repository (GitHub, GitLab, Bitbucket, etc.) Properly configured Security Groups: Port 8080 open on Tomcat instance Port 22 open for SSH (optional) 📦 Installing Jenkins on Amazon Linux ✅ Prerequisites 👉 Before you begin, ensure you have: Basic Linux knowledge AWS EC2 instance (Amazon Linux 2) Internet access SSH access to the instance 🛠 Step 1: Update Your System sudo yum update -y ☕ Step 2: Install Java (Required for Jenkins) sudo yum install java-17-amazon-corretto -y ✅ Verify Java version: java -version 📦 Step 3: Add Jenkins Repository sudo wget -O /etc/yum.repos.d/jenkins.repo https://pkg.jenkins.io/redhat-stable/jenkins.repo sudo rpm –import https://pkg.jenkins.io/redhat-stable/jenkins.io-2023.key sudo yum upgrade 🧰 Step 4: Install Jenkins sudo yum install jenkins -y 🔄 Step 5: Start and Enable Jenkins sudo systemctl start jenkinssudo systemctl enable jenkinssudo systemctl status jenkins 🌐 Step 6: Allow Port 8080 in Security Group 🔐 Steps to allow traffic on port 8080: Go to EC2 Dashboard Select your Instance Click on the linked Security Group Click Edit Inbound Rules Click Add Rule: Type: Custom TCP Port Range: 8080 Source: Anywhere (or your IP) Click Save Rules ✅ Now your Jenkins server is publicly accessible via port 8080. 🔐 Step 7: Access Jenkins UI Open browser: http://<your-ec2-public-ip>:8080 Get the initial password: sudo cat /var/lib/jenkins/secrets/initialAdminPassword Paste it into Jenkins and complete the setup wizard. 🔌 Optional: Install Plugins Choose “Install Suggested Plugins” when prompted during setup. These plugins will help you get started faster. 🧱 Part 1: Tomcat Setup on Separate EC2 Instance 🔹 Step 1: SSH into the Tomcat EC2 Instance ssh ec2-user@<tomcat-public-ip> 🔹 Step 2: Install Java sudo suyum update -yyum install java-17-amazon-corretto 🔹 Step 3: Install Apache Tomcat cd /opt/wget https://dlcdn.apache.org/tomcat/tomcat-9/v9.0.106/bin/apache-tomcat-9.0.106.tar.gzmv apache-tomcat-9.0.106.tar.gz tomcat.tar.gztar -xvf tomcat.tar.gz 🔹 Step 4: Configure Tomcat for Remote Deployment Edit tomcat-users.xml sudo nano /opt/tomcat/conf/tomcat-users.xml Add <role rolename=”manager-script”/><user username=”jenkins” password=”jenkins123″ roles=”manager-script”/> Do not add manager-gui role together with manager-script. Allow Remote Access in context.xml sudo nano /opt/tomcat/webapps/manager/META-INF/context.xml Change the line: <Valve className=”org.apache.catalina.valves.RemoteAddrValve”allow=”127.d+.d+.d+|::1″/> To: <Valve className=”org.apache.catalina.valves.RemoteAddrValve”allow=”.*”/> ⚠️ For production, replace .* with Jenkins private IP. Start Tomcat sudo chmod +x /opt/tomcat/bin/*.shsudo /opt/tomcat/bin/startup.sh Verify Tomcat is running: curl http://localhost:8080 🔧 Part 2: Jenkins Setup and Job Configuration 🔹 Step 1: Install Required Jenkins Plugins Go to Manage Jenkins → Manage Plugins → Available tab, and install: ✅ Maven Integration Plugin✅ Deploy to container Plugin✅ Credentials Plugin 🔹 Step 2: Create a Freestyle Project in Jenkins Open Jenkins dashboard Click New Item Choose Freestyle project Name it devopsProject 🔹 Step 3: Configure Git Source Under Source Code Management: Choose Git Enter the repository URL Add credentials if required 📦 Sample Repo Use this sample Java Maven project: 👉 https://github.com/srtechops/SampleJavaWebApp 🔹 Step 4: Set Build Triggers – Poll SCM Every Minute 🔄 Enable Poll SCM in Jenkins Job 📌 Step-by-Step Go to your Jenkins job: Dashboard → Your Job → Configure Scroll to Build Triggers section ✅ Check the option: ☑️ Poll SCM In the Schedule textbox, enter: * * * * * 🕒 Explanation of Cron Format * * * * * │ │ │ │ │ │ │ │ │ └─ Day of week (0 – 7) [0 or 7 = Sunday] │ │ │ └─── Month (1 – 12) │ │ └───── Day of month (1 – 31) │ └─────── Hour (0 – 23) └───────── Minute (0 – 59) ✅ * * * * * → Every minute 🛑 This does not run the build every minute — it checks Git for changes every minute, and triggers the build only if there are changes. 🔹 Step 5: Configure Maven Build Step Under Build → Invoke top-level Maven targets Goals: clean package This will build your WAR file in target/ 🔹 Step 6: Deploy WAR to Remote Tomcat Under Post-build Actions → Add post-build action → Deploy war/ear to a container Fill in the following: Field Value WAR/EAR files **/target/*.war Context Path /myapp Container Tomcat 9.x Remote Tomcat URL http://<tomcat-private-ip>:8080 Credentials Add jenkins/jenkins123 if not already added 🧪 Test Deployment Click Build Now in Jenkins. Console output should show: [DeployPublisher][INFO] Deploying … to container Tomcat 9.x Remote Finished: SUCCESS Visit: http://<tomcat-public-ip>:8080/myapp/ ✅ Your Java app should now be live! 🐞 Common Issues & Fixes Error Reason Fix 401 Unauthorized Wrong credentials Verify tomcat-users.xml 403 Access Denied IP not allowed in context.xml Update allow=”.*” or specific IP WAR not found Wrong WAR path Ensure correct build & target path Jenkins can’t reach Tomcat Network issues Check security group & private IP 🔐 Security Tips Use private IPs for Jenkins ⇄ Tomcat communication Restrict Tomcat’s port 8080 to Jenkins instance only Use a reverse proxy (e.g., Nginx) + HTTPS in production Use strong passwords in tomcat-users.xml ✅ Summary ✅ Task Status Jenkins and Tomcat on separate EC2 instances ✅ WAR deployment using Jenkins ✅ Poll SCM every minute for Git changes ✅ Secure remote Tomcat access configured ✅ https://srtechops.com/wp-content/uploads/2025/01/Remainder-App-Technology-Logo.mp4 Devops Multi cloud Training Choose the training style that fits your schedule

🚀 Step-by-Step Guide: Installing Terraform on AWS EC2 Amazon Linux

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Terraform is a powerful Infrastructure as Code (IaC) tool that allows for efficient management and provisioning of infrastructure. Installing Terraform on AWS EC2 enables users to automate infrastructure setup directly on scalable cloud instances. This guide walks you through installing Terraform on AWS EC2 using Amazon Linux for a smooth and reliable setup. Whether you’re new to cloud automation or a DevOps engineer, installing Terraform on AWS EC2 is a critical step in streamlining infrastructure management. ✅ Prerequisites Before we begin, make sure you have the following: 🗂️ An AWS account 🖥️ An EC2 Amazon Linux instance up and running 🔑 SSH access to your instance using a key pair (PEM file) 📟 A terminal or SSH client (like PuTTY, Mobaxterm, or an equivalent) 🛠️ Step 1: Setting Up an EC2 Instance Ensure your EC2 instance is properly configured. Navigate to the AWS Management Console and follow these steps to verify your EC2 instance’s status: Go to the EC2 Dashboard in the AWS Management Console. ✅ Check that your instance is running. 📋 Copy the SSH Client Command of your instance, which will be required for SSH access. 🔗 Step 2: Connect to Your EC2 Instance Using SSH (Linux/macOS) Use the below command to connect via SSH: ssh -i /path/to/your-key.pem ec2-user@your-instance-public-ip Using PuTTY (Windows) 💻 Download and install PuTTY. Convert your .pem key to a .ppk key using PuTTYgen (included with PuTTY). Open PuTTY and enter your EC2 instance’s public IP address in the Host Name field. Under Connection > SSH > Auth, browse and select your .ppk file. Click Open to connect. Using Mobaxterm (Windows) 📦 Download and install Mobaxterm. Select Session > SSH. Enter your EC2 instance’s public IP address. Provide the username (ec2-user) and browse for your .pem key under the Advanced SSH settings. Click OK to start the SSH session. 🔄 Step 3: Update the System Ensure your system is up-to-date by running: sudo yum update -y # For Amazon Linux 🧰 Step 4: Install yum-config-manager to Manage Your Repositories Install the necessary dependencies using the appropriate command: sudo yum install -y yum-utils 🌐 Step 5: Add the Official HashiCorp Linux Repository Add the official HashiCorp Linux repository to your instance using yum-config-manager: sudo yum-config-manager –add-repo https://rpm.releases.hashicorp.com/AmazonLinux/hashicorp.repo 📦 Step 6: Install Terraform from the New Repository Install Terraform using yum: sudo yum -y install terraform Verify the installation: terraform -v You should see the installed version of Terraform. 🎉 Conclusion You have successfully installed Terraform on your AWS EC2 Amazon Linux instance. From here, you can start building and managing cloud infrastructure using Terraform. If you have any questions or face issues, feel free to comment below! 💬 https://srtechops.com/wp-content/uploads/2025/01/Remainder-App-Technology-Logo.mp4 Devops Multi cloud Training Choose the training style that fits your schedule — Self-Paced or Live Interactive Sessions. Both include hands-on projects, expert support, and lifetime access. Feature Self-Paced Training Live Training 🎯 Mode 🎥Pre-Recorded Session 🧑‍🏫Live Class + Recordings 💼 Projects 🕒 Weekend Real-Time Projects 📅 Weekdays + Weekend Real-Time Projects ❓ Doubt Clearing 📞 Weekend Live Support Session 🧠 Anytime Doubt Clearing Session 👥 Career Support & Mentorship ❌ No ✅ Yes 🎓 Global Certification Training ❌ No ✅ Yes 🔑 Access ♾️ Lifetime Access ♾️ Lifetime Access 💰 Fees ₹4,999 (2 x ₹2,500) ₹7,999 (2 x ₹4,000) ℹ️ For More Info Explore Self-Paced Training Explore Live Training

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