AWS Interview Questions for Freshers

1. What is AWS?
   AWS (Amazon Web Services) is a cloud computing platform that provides a wide range of services, such as computing, storage, networking, databases, analytics, machine learning, and security. Users can access these services over the Internet and are billed on a pay-as-you-go basis. AWS is widely used to build and run applications and services without managing physical infrastructure.

2. What is AWS SNS?
   AWS SNS (Simple Notification Service) is a managed messaging service that allows sending notifications to various endpoints, including mobile devices, email addresses, and distributed systems. It's used for decoupling microservices and building scalable notification systems in applications like mobile apps, e-commerce platforms, and IoT.

3. What is CloudFront?
   CloudFront is Amazon's content delivery network (CDN) service that speeds up the delivery of web content globally. It uses edge locations to reduce latency and enhance website performance. CloudFront integrates with other AWS services and offers security features like encryption.

4. What is a T2 instance?
   T2 instances are virtual machines in Amazon EC2 designed to provide a balanced mix of compute, memory, and network performance. They are cost-effective and suitable for workloads with variable CPU requirements that may need to burst to higher performance levels.

5. What is AWS Lambda?
   AWS Lambda is a serverless computing platform that automatically manages underlying compute resources. It allows running code in response to events, such as HTTP requests or data changes, without the need to manage infrastructure or scale.

6. What is a Serverless application in AWS?
   A serverless application in AWS runs in a fully managed environment, such as AWS Lambda. AWS handles running and scaling the application, and users are charged only for the compute time they consume. Serverless applications consist of functions triggered by events, providing a cost-effective and scalable way to build and run services.

7. What is the use of Amazon ElastiCache?
   Amazon ElastiCache is a fully managed in-memory data store and cache service used to improve the performance of applications that require fast data access. It supports Memcached and Redis and can cache frequently accessed data, store session data, and more to enhance system performance.

8. Explain how the buffer is used in Amazon web services.
   In AWS, a buffer is a temporary data store used to smooth out bursts of traffic or spikes in demand in distributed systems. It's commonly used in services like Elastic Load Balancer (ELB), Kinesis Data Streams, and ElastiCache to ensure the system functions effectively, even during sudden traffic increases.

9. What are the main differences between 'horizontal' and 'vertical' scaling? Horizontal scaling involves adding more machines to a distributed system to increase its capacity, while vertical scaling involves adding more resources (CPU, memory, etc.) to a single machine to boost its capacity. Horizontal scaling is often more cost-effective and elastic, while vertical scaling can provide better performance on a single machine.

10. Will you use Encryption for S3?
    Yes, encryption is used for Amazon S3 by default. Data stored in S3 is encrypted at rest using either Amazon S3-managed keys (SSE-S3) or customer-managed keys (SSE-C). Additionally, client-side encryption can be applied before uploading data to S3 for added security.

11. What is Identity Access Management and how is it used?
    Identity and Access Management (IAM) is an AWS service used to securely manage access to resources. It allows the creation of users and groups with specific permissions for AWS resources. IAM is essential for access control, security, and compliance with various regulations.

12. Explain the advantages of AWS's Disaster Recovery (DR) Solution.
    AWS's Disaster Recovery solutions offer scalability, flexibility, cost-effectiveness, security, and reliability. AWS allows you to create customized DR solutions that can automatically scale to meet demands and replicate data across regions, ensuring business continuity and minimizing downtime during disasters.

13. What are the different types of Load Balancers in EC2?
    Amazon EC2 offers three types of load balancers: Application Load Balancer (ALB), Network Load Balancer (NLB), and Classic Load Balancer (CLB). ALB is used for routing based on content, NLB for IP and port, and CLB for both content and IP/port routing.

14. What is DynamoDB?
    DynamoDB is a managed NoSQL database service provided by AWS. It offers fast and predictable performance with seamless scalability, making it suitable for various use cases. DynamoDB provides features like automatic scaling, global replication, and strong security.

15. What is AWS CloudFormation?
    AWS CloudFormation is a service for provisioning and managing AWS resources using templates. Users define resources and their dependencies in templates, then create and manage stacks based on those templates. CloudFormation automates infrastructure management and ensures consistency.

16. What are the advantages of using AWS CloudFormation?
    AWS CloudFormation offers advantages like automation, version control, reusability, collaboration, manageability, infrastructure as code, and dependency management. It simplifies resource management, enhances collaboration, and provides consistency in infrastructure deployment.

17. What is Elastic Beanstalk?
    Elastic Beanstalk is a managed service for deploying and running web applications and services. It simplifies application deployment by handling infrastructure details and supports various programming languages and web containers, allowing developers to focus on code development.

18. What is Geo Restriction in CloudFront?
    Geo restriction in CloudFront allows you to control which countries or regions can access your content. It helps comply with legal requirements, protect intellectual property, and improve performance by restricting access based on geographic location.

19. Differentiate between stopping and terminating an instance.
    Stopping an instance shuts down the VM but retains EBS volumes, allowing you to restart it. Terminating an instance shuts down the VM and deletes the EBS volumes, making it irrecoverable. Choose stopping for temporary pauses retaining data, and terminating when you no longer need the instance.

20. Is it possible to change the Private IP Addresses of an EC2 while it is Running/Stopped in a VPC?
    In general, it is not possible to change the private IP address of an EC2 instance while it is running or stopped in a VPC. Private IP addresses are assigned at instance launch and are retained for the instance's lifetime. However, there are exceptions, such as changing secondary private IP addresses or associating/disassociating Elastic IP addresses for public IP changes.

21. Give one instance where you would prefer Provisioned IOPS over Standard RDS Storage.
    Provisioned IOPS (Input/Output Operations Per Second) in Amazon RDS is preferable when you require predictable and consistent database performance for applications with high I/O demands, such as online transaction processing (OLTP) systems. Standard RDS storage provides a baseline level of performance without a guaranteed minimum IOPS, so Provisioned IOPS is the choice for applications requiring a stable and known level of performance.

22. What are the different types of Cloud Services?
    Cloud services are typically categorized into three main types:

• Infrastructure as a Service (IaaS)

• Platform as a Service (PaaS)

• Software as a Service (SaaS)

  1. What is the boot time for an instance store-backed instance?
     The boot time for an instance store-backed instance in AWS can vary depending on factors such as the instance type and the AMI (Amazon Machine Image) used. Generally, instance store-backed instances boot faster than EBS-backed instances because they rely on locally attached instance store volumes.

  2. What is Cross-Region Replication in S3?
     Cross-Region Replication is a feature in Amazon S3 that allows you to replicate objects (files) between S3 buckets in different AWS regions. It provides redundancy, compliance, and data locality options, ensuring data availability in multiple geographic locations.

  3. What is an Availability Zone (AZ) in AWS?
     An Availability Zone (AZ) is an isolated data center within an AWS region that is designed to be highly available and fault-tolerant. Multiple AZs within a region are interconnected to provide redundancy and resiliency. Users can deploy resources in different AZs to achieve fault tolerance and improve the availability of their applications.

  4. What is an Elastic IP in AWS, and why would you use it?
     |An Elastic IP is a static, public IPv4 address that can be associated with an AWS resource, such as an EC2 instance. It's used to mask instance or resource failures by allowing you to quickly remap the Elastic IP to another resource. Elastic IPs are particularly useful when hosting applications that require a consistent public IP address, like web servers.

  5. What is Amazon RDS, and how is it different from self-hosted databases? Amazon RDS (Relational Database Service) is a managed database service that simplifies database administration tasks, such as patching, backups, and scaling. It supports multiple database engines (e.g., MySQL, PostgreSQL, SQL Server). The key difference from self-hosted databases is that AWS manages the underlying infrastructure and database software, allowing you to focus on application development rather than database administration.

  6. What is the difference between Auto Scaling and Load Balancing in AWS?
     Auto Scaling and Load Balancing are two different AWS services. Auto Scaling automatically adjusts the number of EC2 instances in a group based on changing demand, ensuring performance and cost-efficiency. Load Balancing, on the other hand, distributes incoming traffic across multiple instances to improve application availability and fault tolerance. They can be used together to create highly available and scalable applications.

  7. What is Amazon S3 Select?
     Amazon S3 Select is a feature of Amazon S3 that allows you to retrieve specific data from objects stored in S3, without the need to retrieve the entire object. It's useful for filtering and processing data within large datasets efficiently.

  8. What are the different storage classes in Amazon S3?
     Amazon S3 offers various storage classes designed for different use cases and cost considerations. Common storage classes include STANDARD, INTELLIGENT_TIERING, ONEZONE_IA, and GLACIER, each with different performance characteristics and costs. You can choose the storage class that best fits your specific needs.

  9. Explain what VPC Peering is in AWS.
     VPC Peering is a mechanism in AWS that allows you to connect two Virtual Private Clouds (VPCs) to enable private network communication. It allows resources in one VPC to communicate with resources in another VPC using private IP addresses as if they were in the same network while maintaining isolation and security.

  10. What is the difference between Amazon S3 and Amazon EBS?
      Amazon S3 (Simple Storage Service) is a scalable object storage service used for storing and retrieving data, while Amazon EBS (Elastic Block Store) is a scalable block storage service primarily used for attaching block storage volumes to EC2 instances. S3 is suitable for storing objects like files, images, and backups, whereas EBS is used for block-level storage within instances, such as for operating system volumes.

  11. What is the AWS Identity Federation, and how does it work?
      AWS Identity Federation allows external identities to access AWS resources securely. It works by establishing trust between your organization's identity provider (IdP) and AWS. Users log in through the IdP, and the IdP generates temporary AWS credentials, enabling users to access AWS resources based on permissions and roles.

  12. Explain the difference between Simple Queue Service (SQS) and Simple Notification Service (SNS) in AWS.
      SQS is a message queuing service that decouples the components of a cloud application, allowing them to communicate asynchronously. SNS, on the other hand, is a notification service used for distributing messages to multiple subscribers. While SQS stores messages for consumption, SNS delivers messages to subscribers in real time. SQS is often used for building distributed, fault-tolerant systems, while SNS is used for event notifications.

  13. What is AWS Elastic Load Balancing (ELB), and how does it work?
      AWS Elastic Load Balancing is a service that distributes incoming traffic across multiple EC2 instances or IP addresses to ensure high availability, fault tolerance, and optimal application performance. It automatically routes traffic to healthy instances and can be used with different load balancer types, including Application Load Balancer, Network Load Balancer, and Classic Load Balancer.

  14. What is the AWS Shared Responsibility Model?
      The AWS Shared Responsibility Model defines the division of security responsibilities between AWS and its customers. AWS is responsible for the security of the cloud (physical infrastructure, hypervisor, etc.), while customers are responsible for securing their data in the cloud (configuring resources securely, applying security patches, and managing access controls). The exact responsibilities depend on the type of AWS service being used.

  15. What are the benefits of using Amazon S3 over a traditional file server for storing files?
      Amazon S3 offers benefits like scalability, durability, high availability, versioning, cost-effectiveness, and the ability to serve as a backup and archive solution. It's designed for web-scale storage and can handle large volumes of data with minimal management overhead.

  16. What is AWS Key Management Service (KMS), and why is it important?
      AWS KMS is a managed service that allows you to create and control encryption keys to protect your data in AWS. It's essential for securing data at rest and in transit, ensuring confidentiality and compliance. KMS provides centralized key management and integrates with various AWS services.

  17. Explain the concepts of Elastic Network Interfaces (ENIs) and Elastic IP addresses.
      Elastic Network Interfaces (ENIs) are virtual network interfaces that can be attached to EC2 instances. They provide network connectivity and security groups. Elastic IP addresses are static, public IPv4 addresses that can be associated with ENIs or EC2 instances. ENIs can be moved between instances, making them useful for scenarios where IP address stability is needed.

  18. What is AWS Data Pipeline?
      AWS Data Pipeline is a web service for orchestrating and automating the movement and transformation of data between different AWS services and on-premises data sources. It's used for activities like data migration, log processing, and data transformation.

  19. What is AWS CloudFormation, and how does it work?
      AWS CloudFormation is a service that allows you to define and provision AWS infrastructure as code. It uses templates (JSON or YAML files) to create and manage stacks of AWS resources in a predictable and repeatable way. This enables you to automate the deployment and management of your infrastructure.

  20. What is an AWS Lambda function, and what are its use cases?
      AWS Lambda is a serverless compute service that runs code in response to events. You can use it to build serverless applications, automate tasks, process data, and more. Lambda functions are event-driven and scale automatically, so you don't need to manage servers.

  21. What is Amazon Route 53, and what is its primary purpose?
      Amazon Route 53 is a scalable and highly available Domain Name System (DNS) web service. Its primary purpose is to route end-user requests to endpoints, such as web applications and resources running in AWS or on-premises, by translating human-friendly domain names into IP addresses.

  22. Explain the concept of AWS CloudWatch and AWS CloudTrail.
      AWS CloudWatch is a monitoring service that provides real-time insights into your AWS resources and applications, allowing you to collect and track metrics, collect and monitor log files, and set alarms. AWS CloudTrail, on the other hand, records API requests made on your AWS account and provides a history of AWS resource changes. It's primarily used for auditing and compliance.

  23. What is AWS ECS (Elastic Container Service), and how does it relate to Docker containers?
      AWS ECS is a service for deploying and managing Docker containers at scale. It allows you to easily run and manage containers across a cluster of EC2 instances, providing scalability and orchestration for containerized applications.

  24. Explain what AWS Lambda Layers are and why they are useful.
      AWS Lambda Layers is a distribution mechanism for libraries, custom runtimes, and other function dependencies. They allow you to manage common components separately from your function code, which can help reduce the size of your deployment packages, make updates more manageable, and promote code reuse.

  25. What is Amazon VPC (Virtual Private Cloud), and why is it important?
      Amazon VPC is a virtual network dedicated to your AWS account. It enables you to launch AWS resources into a virtual network that you've defined, providing control over the network configuration, security, and isolation of your resources. It's essential for creating isolated and secure environments within AWS.

  26. What is Amazon EC2 Auto Scaling, and how does it work?
      Amazon EC2 Auto Scaling is a service that automatically adjusts the number of running EC2 instances in response to changes in demand for your application. You can define scaling policies to ensure the right number of instances are available to handle your workload.

  27. Explain the differences between the AWS Regions and Availability Zones.
      AWS Regions are separate geographic areas, such as US East (N. Virginia) and EU (Ireland), where AWS has data centers. Each Region is made up of multiple Availability Zones (AZs), which are physically separate data centers with redundant power, networking, and cooling. Availability Zones within a Region are connected via low-latency links but isolated from one another to provide fault tolerance.

  28. What is Amazon EMR, and when would you use it?
      Amazon EMR (Elastic MapReduce) is a cloud-native big data platform that allows you to process vast amounts of data quickly and cost-effectively using popular open-source tools like Hadoop, Spark, and Hive. You would use it for tasks like data analysis, log processing, and machine learning on large datasets.

These questions and answers should give you a good foundation for understanding various AWS services and concepts. If you have more specific questions or need further clarification on any topic, feel free to ask.