AWS Interview Questions

AWS Interview Questions

What is AWS?

AWS (Amazon Web Services) is a comprehensive and evolving cloud computing platform provided by Amazon. It offers a wide range of services including computing power, storage, databases, machine learning, and more.

What are the key components of AWS?

Some key components of AWS include Amazon EC2 (Elastic Compute Cloud) for scalable computing capacity, Amazon S3 (Simple Storage Service) for object storage, Amazon RDS (Relational Database Service), and Amazon VPC (Virtual Private Cloud) for networking.

What is EC2 in AWS?

EC2 (Elastic Compute Cloud) is a web service that provides resizable compute capacity in the cloud. It allows users to quickly scale compute capacity up or down as needed, and pay only for what they use.

Explain S3 in AWS.

S3 (Simple Storage Service) is an object storage service offered by AWS. It provides developers with secure, durable, and highly scalable storage infrastructure for storing and retrieving data over the internet.

What is the difference between S3 and EBS?

Some key difference between Amazon S3 and Amazon EBS:

Feature Amazon S3 Amazon EBS
Purpose Object storage for large-scale data Block storage for EC2 instances
Data Structure Objects stored in buckets Block-level storage volumes
Access Method Accessed over HTTP/HTTPS using APIs Attached to EC2 instances as block devices
Performance Optimized for scalability and throughput Low-latency access, suitable for databases
Use Cases Backup, archival, content distribution Operating system disks, database storage
Accessibility Accessed from anywhere on the internet Attached to specific EC2 instances

What is IAM in AWS?

IAM (Identity and Access Management) is a service that enables you to securely control access to AWS services and resources. It allows you to manage users, groups, and permissions to grant or deny access to AWS resources.

What is VPC in AWS?

VPC (Virtual Private Cloud) is a virtual network dedicated to your AWS account. It allows you to logically isolate resources within the AWS cloud, providing a secure and customizable network environment.

Explain Lambda in AWS.

AWS Lambda is a serverless computing service that lets you run code without provisioning or managing servers. You can upload your code and Lambda automatically scales to handle requests, charging only for the compute time consumed.

What is CloudFormation?

CloudFormation is a service that enables you to model and provision AWS infrastructure resources using templates. With CloudFormation, you can create, update, and delete resources in a controlled and predictable manner.

What is RDS in AWS?

RDS (Relational Database Service) is a managed database service provided by AWS. It supports several database engines such as MySQL, PostgreSQL, SQL Server, and Oracle, allowing you to easily set up, operate, and scale relational databases in the cloud.

Explain the difference between scalability and elasticity.

Some key difference between scalability and elasticity:

Aspect Scalability Elasticity
Definition Scalability refers to the ability of a system to handle increasing workload by adding resources. Elasticity refers to the ability to automatically provision and de-provision resources based on demand.
Nature Scalability is typically a manual or pre-planned process, where resources are added or removed in response to expected changes in workload. Elasticity is a dynamic and automated process, where resources are automatically adjusted in real-time based on actual demand.
Flexibility Scalability may involve a degree of manual intervention or configuration changes to add or remove resources, depending on the system's architecture. Elasticity requires minimal or no human intervention, as resources are provisioned and de-provisioned automatically based on predefined policies or rules.
Timing Scalability changes may not happen instantaneously and may require some lead time to implement the necessary adjustments. Elasticity allows resources to scale up or down rapidly and seamlessly in response to fluctuating demand, ensuring optimal performance and cost efficiency.
Use Cases Scalability is suitable for workloads with predictable patterns or planned growth, where resources can be provisioned in advance to accommodate anticipated increases in demand. Elasticity is ideal for dynamic workloads with unpredictable or fluctuating demand, such as web applications or cloud-based services, where resources need to scale up or down dynamically to match demand spikes or lulls.

What is Auto Scaling in AWS?

Auto Scaling is a service that automatically adjusts the number of EC2 instances in a group based on conditions you define. It helps ensure that you have the right amount of compute capacity to handle varying levels of demand.

What is CloudWatch?

CloudWatch is a monitoring and observability service provided by AWS. It collects and tracks metrics, logs, and events from various AWS resources and applications, allowing you to gain insights into the performance and health of your infrastructure.

Explain the difference between horizontal scaling and vertical scaling.

Some key difference between horizontal scaling and vertical scaling:

Aspect Horizontal Scaling Vertical Scaling
Definition Horizontal scaling involves adding more instances of resources, such as servers, to distribute the load. Vertical scaling involves increasing the capacity of existing resources, such as upgrading to a larger server.
Resource Addition Resources are added horizontally by adding more instances or nodes to the existing infrastructure. Resources are added vertically by increasing the power, storage, or memory capacity of individual instances.
Scalability Pattern Horizontal scaling follows a "scale out" pattern, where additional instances are added to accommodate increased demand. Vertical scaling follows a "scale up" pattern, where existing instances are upgraded to handle additional workload.
Flexibility Horizontal scaling offers more flexibility and scalability as it can accommodate a larger number of instances to distribute the load. Vertical scaling may have limitations in terms of how much a single instance can be scaled up, depending on hardware constraints.
Fault Tolerance Horizontal scaling improves fault tolerance by distributing the workload across multiple instances, reducing the impact of failures. Vertical scaling may increase vulnerability to hardware failures as all workload is concentrated on a single instance.
Cost Efficiency Horizontal scaling can be more cost-effective as it typically involves using smaller, less expensive instances that can be added or removed as needed. Vertical scaling may incur higher costs, especially for large, high-performance instances or hardware upgrades.

What is an AMI?

An AMI (Amazon Machine Image) is a template that contains the software configuration (operating system, application server, and applications) required to launch an EC2 instance. It serves as the foundation for creating virtual servers in the AWS cloud.

What is CloudFront?

CloudFront is a content delivery network (CDN) service provided by AWS. It delivers static and dynamic web content, including images, videos, and APIs, to users with low latency and high transfer speeds by caching content at edge locations around the world.

What is DynamoDB?

DynamoDB is a fully managed NoSQL database service provided by AWS. It offers seamless scalability, high availability, and low latency for applications requiring single-digit millisecond response times. DynamoDB is ideal for use cases such as gaming, mobile, and web applications.

What is Route 53?

Route 53 is a scalable and highly available Domain Name System (DNS) web service provided by AWS. It allows you to register domain names, route traffic to AWS resources, and perform health checks on your applications and infrastructure.

What is CloudTrail?

CloudTrail is a service that enables governance, compliance, operational auditing, and risk auditing of your AWS account. It provides a comprehensive history of API calls made within your AWS environment, allowing you to track user activity and resource changes.

Explain the difference between a region and an availability zone in AWS.

Some key difference between a region and an availability zone in AWS:

Aspect Region Availability Zone
Definition A region is a geographical area consisting of multiple availability zones, each of which is a distinct location engineered to be isolated from failures in other availability zones. An availability zone (AZ) is a data center or facility within a region, providing redundant and isolated power, networking, and connectivity to AWS services.
Geographic Scope A region typically covers a large geographic area, such as a country or continent, and may have multiple availability zones within it. An availability zone is localized within a region and is identified by a unique ID (e.g., us-east-1a, us-east-1b).
Isolation Regions are entirely separate from one another, meaning they are physically separated and operate independently, with their own infrastructure and resources. Availability zones within a region are interconnected through low-latency links but are designed to be isolated from failures in other availability zones.
Redundancy Regions provide redundancy and fault tolerance by offering multiple availability zones, allowing users to distribute their resources across different zones for high availability. Availability zones are designed to be fault-tolerant and resilient, with redundant power, networking, and hardware infrastructure to minimize the impact of failures.
Use Cases Regions are suitable for deploying applications that require geographic redundancy, data sovereignty, or compliance with local regulations. Availability zones are used to deploy resources within a region for fault tolerance, high availability, and low-latency access to AWS services.

What is the AWS Free Tier?

The AWS Free Tier is a program that offers new AWS users access to certain AWS services for free within specified usage limits for the first 12 months after signing up. It allows users to explore and experiment with AWS services without incurring charges.

What is CloudFormation stack?

A CloudFormation stack is a collection of AWS resources that are created and managed as a single unit. You can use CloudFormation templates to define the resources and their configurations, and then deploy them as a stack.

What is an EIP?

An EIP (Elastic IP address) is a static IPv4 address designed for dynamic cloud computing. It allows you to allocate a persistent IP address and associate it with an EC2 instance, providing a consistent IP address that can be remapped to different instances as needed.

What is an SNS?

SNS (Simple Notification Service) is a fully managed messaging service provided by AWS. It enables you to send messages or notifications to a variety of endpoints, including email, SMS, HTTP, and AWS Lambda, based on events or conditions you define.

What are the native AWS Security logging capabilities?

AWS provides several native security logging capabilities to help monitor and protect your resources:

  • AWS CloudTrail: Records API calls with details like who made the call, what resources were accessed, and when the call occurred.
  • Amazon CloudWatch Logs: Stores and monitors log files from AWS services and custom applications for centralized log management and analysis.
  • AWS Config: Tracks configuration changes to AWS resources for compliance assessment and security vulnerability identification.
  • Amazon GuardDuty: Detects malicious activity and unauthorized behavior in AWS accounts by analyzing logs for security threats.
  • AWS WAF Logs: Captures detailed information about web requests and traffic patterns to protect web applications.
  • VPC Flow Logs: Records IP traffic flow in and out of Virtual Private Clouds for network analysis and security incident response.

What is CloudWatch Logs?

CloudWatch Logs is a service that enables you to monitor, store, and access log files from various AWS resources and applications in real-time. It allows you to centralize log management and gain insights into system and application behavior.

Explain the Shared Responsibility Model in AWS.

The Shared Responsibility Model is a security framework that delineates the division of responsibilities between AWS and the customer. AWS is responsible for the security of the cloud (infrastructure), while the customer is responsible for security in the cloud (data, applications, and configurations).

What is EFS?

EFS (Elastic File System) is a scalable, fully managed file storage service provided by AWS. It allows you to create file systems that can be mounted on multiple EC2 instances simultaneously, providing shared access to files across instances in a VPC.

What is an EC2 instance type?

An EC2 instance type defines the computing, memory, storage, and networking capacity of an EC2 instance. Each instance type is optimized for specific use cases and workloads, such as general-purpose, compute-optimized, memory-optimized, and storage-optimized instances.

What is the difference between a reserved instance and an on-demand instance?

Some key difference between a reserved instance and an on-demand instance:

Aspect Reserved Instance On-Demand Instance
Pricing Model Reserved instances require an upfront payment or commitment for a one- or three-year term, offering significant discounts compared to on-demand instances. On-demand instances are billed at standard rates with no long-term commitment, allowing users to pay only for the compute capacity they consume on an hourly or per-second basis.
Cost Savings Reserved instances offer cost savings of up to 75% compared to on-demand pricing, making them a cost-effective option for predictable workloads with steady usage patterns. On-demand instances provide flexibility and convenience but may incur higher costs, especially for sustained or long-running workloads.
Usage Flexibility Reserved instances provide a fixed capacity and instance type for the duration of the reservation term, offering savings in exchange for commitment. On-demand instances offer flexibility to provision compute capacity on-demand without any long-term commitment, making them suitable for unpredictable workloads or short-term projects.
Reservation Scope Reserved instances are scoped to specific instance types, availability zones, and regions, requiring careful planning and optimization to maximize cost savings. On-demand instances are available across all instance types, availability zones, and regions, providing instant access to compute resources without capacity constraints.
Use Cases Reserved instances are ideal for applications with predictable workloads or steady-state usage, such as production environments or applications with consistent performance requirements. On-demand instances are suitable for dynamic workloads with fluctuating demand, short-term projects, or applications that require flexibility and scalability without long-term commitments.

Explain Elastic Load Balancing (ELB) in AWS.

Elastic Load Balancing (ELB) is a service that automatically distributes incoming application traffic across multiple targets, such as EC2 instances, containers, and IP addresses, to ensure high availability and fault tolerance of your applications.

What is EBS Snapshot?

An EBS Snapshot is a point-in-time copy of an EBS volume stored in Amazon S3. It allows you to back up your data incrementally, enabling fast and efficient data recovery, and can be used to create new EBS volumes or restore existing ones.

What is AWS CloudFormation template?

An AWS CloudFormation template is a JSON or YAML formatted text file that describes the AWS resources and their configurations required to deploy an application or infrastructure stack. CloudFormation uses these templates to automate the provisioning and management of resources.

What is an EC2 security group?

An EC2 security group acts as a virtual firewall for controlling inbound and outbound traffic to EC2 instances. You can define rules that allow or deny traffic based on protocols, ports, and IP addresses, providing granular control over network access to instances.

What is the difference between Amazon RDS and Amazon Aurora?

Some key difference between Amazon RDS and Amazon Aurora:

Aspect Amazon RDS Amazon Aurora
Database Engines Amazon RDS supports multiple database engines, including MySQL, PostgreSQL, SQL Server, Oracle, and MariaDB. Amazon Aurora is a MySQL and PostgreSQL-compatible relational database built for the cloud, offering enhanced performance, availability, and durability.
Performance Amazon RDS provides configurable instance types with varying levels of performance and storage capacity, suitable for a wide range of database workloads. Amazon Aurora offers up to five times the performance of standard MySQL databases and up to three times the performance of standard PostgreSQL databases, making it ideal for high-performance, mission-critical applications.
Scalability Amazon RDS supports horizontal scaling through features like read replicas and Multi-AZ deployments to enhance scalability and fault tolerance. Amazon Aurora offers automatic scaling of storage up to 64TB and supports up to 15 read replicas per instance for read scalability, enabling high availability and performance for demanding workloads.
High Availability Amazon RDS provides Multi-AZ deployments for automatic failover and high availability, ensuring database availability in the event of instance or infrastructure failures. Amazon Aurora offers a highly available architecture with automated failover, continuous backups, and self-healing storage, minimizing downtime and data loss.
Storage Amazon RDS offers scalable storage options such as General Purpose (SSD) and Provisioned IOPS (SSD) volumes, allowing you to optimize storage performance and cost based on your requirements. Amazon Aurora uses a distributed, fault-tolerant storage system designed for high performance and durability, providing consistent and predictable performance for databases of any size.
Cost Amazon RDS pricing varies based on the instance type, database engine, storage type, and usage metrics, with options for both on-demand and reserved instances. Amazon Aurora pricing is based on the instance size and storage usage, with separate pricing for read replicas and Multi-AZ deployments, offering cost-effective options for high-performance databases.

What is AWS Lambda function?

An AWS Lambda function is a piece of code that runs in response to events triggered by AWS services or custom applications. You can write Lambda functions in several programming languages, upload them to AWS, and configure triggers to execute the functions automatically.

What is Amazon Redshift?

Amazon Redshift is a fully managed data warehouse service provided by AWS. It allows you to analyze large datasets using standard SQL queries and business intelligence tools, with high performance and scalability for analytical workloads.

What is AWS Elastic Beanstalk?

AWS Elastic Beanstalk is a Platform as a Service (PaaS) offering that simplifies the deployment and management of web applications and services in the AWS cloud. It automatically handles infrastructure provisioning, load balancing, scaling, and application health monitoring, allowing developers to focus on writing code.

What is AWS Direct Connect?

AWS Direct Connect is a dedicated network connection service that enables you to establish a private, low-latency connection between your on-premises data center or office and the AWS cloud. It provides a more consistent network experience compared to internet-based connections.

What is AWS Key Management Service (KMS)?

AWS Key Management Service (KMS) is a managed service that allows you to create and control the encryption keys used to encrypt your data stored in AWS services and applications. KMS integrates with other AWS services to provide encryption at rest and in transit.

What alternative tools exist for logging into the cloud environment besides the console?

Yes, there are several alternative tools available for accessing AWS resources:

  • Putty: A popular SSH client for securely accessing EC2 instances.
  • AWS CLI for Linux: Command-line interface tool for managing AWS services on Linux systems.
  • AWS CLI for Windows: Command-line interface tool designed for Windows operating systems.
  • AWS CLI for Windows CMD: Command-line interface tool specifically for Windows Command Prompt.
  • AWS SDK: Software Development Kits available in various programming languages for integrating AWS services into applications.
  • Eclipse: An integrated development environment (IDE) that supports AWS development through plugins and extensions.

What is AWS Glue?

AWS Glue is a fully managed extract, transform, and load (ETL) service that makes it easy to prepare and load data for analytics. It automatically discovers, catalogs, and transforms data stored in various sources, allowing you to create and maintain data pipelines effortlessly.

What is AWS ECS?

AWS ECS (Elastic Container Service) is a fully managed container orchestration service that allows you to run, stop, and manage Docker containers on a cluster of EC2 instances. It simplifies the deployment of containerized applications by handling infrastructure management tasks.

What is AWS S3 Glacier?

AWS S3 Glacier is a low-cost archival storage service designed for data archiving and long-term backup. It offers durable, secure, and scalable storage for data that is infrequently accessed and requires long-term retention.

What is AWS WAF?

AWS WAF (Web Application Firewall) is a managed firewall service that protects web applications from common web exploits and malicious attacks. It allows you to define custom rules to filter HTTP and HTTPS traffic based on conditions you specify.

What is AWS ECR?

AWS ECR (Elastic Container Registry) is a fully managed Docker container registry that allows you to store, manage, and deploy Docker container images in the AWS cloud. It integrates seamlessly with other AWS services such as ECS and EKS for containerized application deployment.

What is AWS Kinesis?

AWS Kinesis is a platform for building real-time streaming data applications and analytics solutions. It provides capabilities for collecting, processing, and analyzing large streams of data in real-time, enabling you to derive insights and take action quickly.

What is AWS DynamoDB Accelerator (DAX)?

AWS DynamoDB Accelerator (DAX) is an in-memory caching service that provides high-performance access to DynamoDB tables. It improves response times for read-intensive DynamoDB workloads by caching frequently accessed data and reducing the need for read operations against the DynamoDB table.

What is AWS CodePipeline?

AWS CodePipeline is a continuous integration and continuous delivery (CI/CD) service that automates the build, test, and deployment phases of your software release process. It allows you to define and visualize your release pipelines, enabling rapid and reliable software delivery.

What is AWS Secrets Manager?

AWS Secrets Manager is a managed service that helps you securely store, rotate, and retrieve secrets such as API keys, passwords, and database credentials. It provides a centralized repository for managing secrets and integrates with other AWS services for secure access.

What is AWS Certificate Manager (ACM)?

AWS Certificate Manager (ACM) is a service that simplifies the process of provisioning, managing, and deploying SSL/TLS certificates for use with AWS services and applications. It provides free SSL/TLS certificates that are automatically renewed, reducing the complexity and cost of certificate management.

What is geo-targeting in CloudFront?

Geo-targeting is a dynamic marketing strategy that tailors content or advertisements to specific geographic locations, without altering the URL. By leveraging geo-targeting, businesses can deliver personalized content to audiences based on their location, thereby catering to their unique needs and preferences. This approach enhances user engagement and relevance, optimizing the effectiveness of marketing campaigns across diverse regions and demographics.

How do you upgrade or downgrade a system with near-zero downtime?

You can upgrade or downgrade a system with near-zero downtime using the following steps of migration:

  • Navigate to the EC2 console to initiate the process.
  • Select an appropriate Operating System AMI to match your requirements.
  • Launch a new instance using the chosen instance type, ensuring compatibility and optimal performance.
  • Perform thorough updates, including patches and security enhancements, to fortify the system.
  • Install essential applications and dependencies essential for seamless functionality.
  • Rigorously test the new instance to validate its stability and performance under real-world conditions.
  • Upon successful testing, execute the deployment process, seamlessly transitioning from the older instance to the upgraded/downgraded one.
  • Once the deployment is complete, swiftly verify system functionality to confirm uninterrupted operations.

What are the different types of virtualization in AWS

In AWS, there are primarily three types of virtualization used to provide computing resources:

Hardware Virtualization

This is the most common type of virtualization used in AWS. It involves running multiple virtual machines (EC2 instances) on a single physical server using a hypervisor. Each virtual machine operates as an independent server with its own operating system and resources.

Container Virtualization

AWS supports containerization through services like Amazon ECS (Elastic Container Service) and Amazon EKS (Elastic Kubernetes Service). Containers package applications and their dependencies into a single unit, providing lightweight and portable runtime environments.

Serverless Computing

While not traditional virtualization, serverless computing (e.g., AWS Lambda) abstracts away the underlying infrastructure entirely. Developers can run code without provisioning or managing servers, paying only for the compute time consumed. This approach offers high scalability and eliminates the need to manage virtual machines or containers.

What is AWS Snowball?

AWS Snowball is a petabyte-scale data transport solution that enables you to securely transfer large amounts of data into and out of the AWS cloud using physical storage devices. It accelerates data migration by bypassing internet bandwidth limitations and can be used for offline data transfer.