AWS Interview Questions

AWS (Amazon Web Services) is a comprehensive and widely adopted cloud computing platform provided by Amazon. It offers on-demand services like computing power, storage, databases, machine learning, analytics, and more—all accessible over the internet.

Reasons for AWS's popularity include:

• Scalability: Easily scale up or down based on demand without provisioning physical infrastructure.
• Cost-Effectiveness: Pay-as-you-go model helps businesses reduce upfront costs.
• Global Reach: Data centers across the world offer high availability and low latency.
• Security: Strong compliance standards and built-in tools to secure data and resources.
• Extensive Services: Offers 200+ services ranging from compute and storage to AI, DevOps, and IoT.
• Innovation: Rapid release of new features and services for modern applications.

These advantages make AWS a go-to choice for startups, enterprises, and developers to host applications, analyze data, and manage infrastructure at scale.

Amazon EC2 (Elastic Compute Cloud) is a service that provides resizable compute capacity in the AWS cloud. An EC2 instance is essentially a virtual server that you can configure and manage just like a physical machine.

How it works:

• You start by selecting an Amazon Machine Image (AMI), which is a pre-configured template that includes an operating system and optional software (e.g., Ubuntu + NGINX).
• Next, you choose an instance type, which defines the hardware specs such as CPU, RAM, storage, and network capacity.
• When launched, AWS provisions the virtual machine on their physical infrastructure, and you're given access via SSH (for Linux) or RDP (for Windows).
• You can also attach EBS volumes for storage, configure security groups for access control, and use key pairs for authentication.

EC2 gives you full control over your computing environment and allows you to run applications reliably and securely in the cloud with flexible scaling options.

Amazon S3 and Amazon EBS are both storage services provided by AWS, but they serve different purposes and operate in distinct ways. Below is a comparison highlighting the major differences:

Key Differences Between Amazon S3 and Amazon EBS:

Amazon Snowball is a physical data transport solution that helps users move large amounts of data (typically in the range of terabytes to petabytes) into and out of the AWS cloud securely and efficiently.

• It is used when network-based data transfer is too slow or impractical.
• Snowball devices are rugged, portable, and come with built-in security features including tamper resistance and 256-bit encryption.
• You can use Snowball for data migration, disaster recovery, content distribution, or long-term data archiving.
• Once the data is loaded onto the Snowball device, it is shipped to AWS where the data is imported into the designated AWS service (like S3).

Overall, Snowball is a reliable option when dealing with massive datasets and limited bandwidth.

Auto Scaling in AWS automatically adjusts the number of EC2 instances based on real-time traffic demands and predefined policies. It ensures optimal performance during peak traffic by adding instances and improves cost efficiency during low traffic by reducing the number of instances. This helps maintain high availability while optimizing resource usage.

AWS regions are separate geographical locations, such as US-West-1 (North California) or Asia South (Mumbai). Each region contains multiple Availability Zones (AZs), which are isolated data center locations. AZs are designed to be independent yet capable of replicating data between each other for fault tolerance and high availability.

Auto-scaling is a feature in AWS that automatically provisions or terminates instances based on demand. It ensures that the right amount of resources are available to handle application traffic, optimizing performance and cost.

Geo-targeting allows businesses to display personalized content to users based on their geographic location without changing the URL. This feature enables delivering customized experiences for different audiences in various regions.

You can upgrade or downgrade a system with minimal downtime by following these steps:

1. Open the EC2 console
2. Select an appropriate Operating System AMI
3. Launch a new instance with the required instance type
4. Install all updates and necessary applications
5. Test the new instance for functionality
6. If successful, deploy the new instance and replace the old one

You can use Amazon CloudWatch Logs to collect logs, store them in Amazon S3, and use Amazon Elasticsearch Service to visualize them. Additionally, Amazon Kinesis Firehose can be used to stream data from S3 to Elasticsearch for near real-time analysis.

Some native AWS logging capabilities include:

• AWS CloudTrail: Provides a history of AWS API calls for an account. Can be configured to send notifications via Amazon SNS when new logs are delivered.
• AWS Config: Tracks configuration changes and relationships between resources, with notifications available through SNS.

Not all AWS services are available in every region immediately upon launch. AWS typically rolls out services gradually. If a service is not available in your region, you can switch to the nearest region where it is supported.

The three major types of virtualization in AWS are:

• Hardware Virtual Machine (HVM): Fully virtualized hardware where each VM runs independently. VMs boot by executing a master boot record in the root block device of the image.
• Paravirtualization (PV): Uses the PV-GRUB bootloader to start AMIs. It loads the kernel specified in the menu configuration.
• Paravirtualization on HVM (PV on HVM): Combines the advantages of PV with HVM, allowing operating systems to take advantage of enhanced storage and network I/O performance.

Some AWS services operate at the global level and are not restricted to a specific region. Examples include:

• Identity and Access Management (IAM)
• Amazon Route 53
• AWS Web Application Firewall (WAF)
• Amazon CloudFront

Amazon CloudWatch is a monitoring and observability service for AWS resources and applications. Key features include:

• Monitoring AWS services such as EC2, RDS, S3, ELB, SNS, and more.
• Triggering alarms based on custom-defined metrics.
• Collecting and tracking log data.

Amazon Elastic Transcoder is a media transcoding service in the cloud. It allows converting media files into formats and resolutions compatible with multiple devices, such as laptops, tablets, and smartphones.

It is:

• Easy to use
• Cost-effective
• Highly scalable

Amazon EC2 offers several types of instances to meet different workload needs:

• General Purpose Instances: Provide a balance of compute, memory, and networking resources for a wide variety of workloads.
• Compute Optimized Instances: Designed for compute-intensive workloads such as batch processing, high-performance web servers, and machine learning inference.
• Memory Optimized Instances: Ideal for workloads requiring large datasets to be processed in memory quickly.
• Accelerated Computing Instances: Use hardware accelerators for floating-point calculations, graphics processing, and data pattern matching.
• Storage Optimized Instances: Designed for workloads that require high sequential read and write access to large datasets on local storage.

No. Standby RDS instances are launched in a different Availability Zone than the primary instance. This ensures physical separation and infrastructure redundancy, enabling data recovery and failover in case of primary instance failure.

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 maintain application availability and performance.

Key benefits include:

• Traffic Distribution: Prevents overloading any single resource by balancing traffic intelligently.
• Fault Tolerance: Routes traffic across multiple Availability Zones to maintain service continuity during failures.
• Scalability: Adjusts traffic distribution dynamically to handle spikes in demand.

AWS offers a range of services that streamline development, deployment, and operations for DevOps practices:

• Elastic Compute Cloud (EC2) for scalable computing power.
• Elastic Container Service (ECS) for container orchestration.
• Elastic Beanstalk for simplified application deployment.
• Support for Infrastructure as Code (IaC) via AWS CloudFormation and Terraform.
• Built-in CI/CD tools like CodePipeline and CodeBuild.
• Monitoring and logging tools such as CloudWatch and CloudTrail.