CLOUD COMPUTING INTERVIEW NOTES (AWS Cerification Based)
*(Mainly refer Service, Deployment models, Advantages, Architecture)*

1. What is Cloud Computing?

Cloud Computing is the delivery of computing services such as servers, storage, databases, networking, software, analytics, and AI over the Internet instead of using physical hardware. It allows users to access resources on demand and pay only for what they use.

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2. Advantages of Cloud Computing

• Pay-as-you-go pricing
• High Availability
• Scalability
• Reliability
• Cost Effective
• Faster Deployment
• Global Access
• Automatic Updates
• Better Security
• Disaster Recovery

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3. Cloud Deployment Models

Public Cloud

The cloud infrastructure is owned and managed by a third-party cloud provider and is accessible over the Internet by multiple users.

Examples:
• AWS
• Microsoft Azure
• Google Cloud Platform (GCP)

Best for:
Startups, web applications, and businesses looking for cost-effective cloud services.

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Private Cloud

The cloud infrastructure is dedicated to a single organization and offers greater control, security, and customization.

Example:
An organization's own internal cloud infrastructure.

Best for:
Banks, government organizations, and healthcare institutions handling sensitive data.

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Hybrid Cloud

A combination of Public Cloud and Private Cloud, allowing data and applications to move between both environments.

Example:
A company stores sensitive customer data in a private cloud while hosting its website on AWS.

Best for:
Organizations that need both security and flexibility.

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Community Cloud

A cloud infrastructure shared by multiple organizations with similar security or compliance requirements.

Example:
Hospitals or government departments sharing a common cloud environment.

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4. Cloud Service Models

IaaS (Infrastructure as a Service)

Provides virtual servers, storage, networking, and other infrastructure resources. The customer manages the operating system and applications.

Examples:
• Amazon EC2
• Amazon EBS
• Amazon VPC

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PaaS (Platform as a Service)

Provides a complete platform for developing, testing, and deploying applications without managing the underlying infrastructure.

Examples:
• AWS Elastic Beanstalk
• AWS Lambda
• Google App Engine

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SaaS (Software as a Service)

Provides ready-to-use software applications over the Internet. Users only need a web browser to access the software.

Examples:
• Gmail
• Microsoft 365
• Salesforce
• Zoom

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Difference Between IaaS, PaaS, and SaaS

IaaS
• Provides Infrastructure
• User manages OS and applications
• Example: EC2

PaaS
• Provides Platform
• User focuses only on application development
• Example: Elastic Beanstalk

SaaS
• Provides Complete Software
• User simply uses the application
• Example: Gmail

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5. AWS Global Infrastructure

AWS Global Infrastructure consists of:

• Regions
• Availability Zones
• Edge Locations

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Region

A Region is a geographical area where AWS maintains multiple data centers.

Examples:
• Mumbai
• Singapore
• Frankfurt
• Ohio

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Availability Zone (AZ)

An Availability Zone is one or more physically separate data centers within a Region.

Purpose:
• High Availability
• Fault Tolerance

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Edge Location

Edge Locations are used for fast content delivery through Amazon CloudFront.

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6. AWS Shared Responsibility Model

AWS is responsible for Security OF the Cloud.

This includes:
• Physical Security
• Hardware
• Networking
• Data Centers
• Cloud Infrastructure

Customer is responsible for Security IN the Cloud.

This includes:
• IAM Users
• Passwords
• Applications
• Operating System
• Data
• Network Configuration

Remember:
AWS secures the Cloud.
Customer secures everything IN the Cloud.

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7. AWS Pricing Models

• On-Demand
• Reserved Instances
• Spot Instances
• Savings Plans

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8. Scalability vs Elasticity

Scalability

The ability to increase or decrease resources based on business needs. It can be manual or automatic.

Elasticity

The ability to automatically add or remove resources depending on workload in real time.

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9. High Availability

High Availability ensures that an application continues running even if one server fails.

Achieved using:
• Multiple Availability Zones
• Load Balancer
• Auto Scaling

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10. Fault Tolerance

Fault Tolerance is the ability of a system to continue operating even when one or more components fail.

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TOP CLOUD QUESTIONS

• What is Cloud Computing?
• What are the advantages of Cloud Computing?
• What are the Cloud Deployment Models?
• Explain Public, Private, Hybrid, and Community Cloud.
• What are the Cloud Service Models?
• Explain IaaS, PaaS, and SaaS with examples.
• What is the difference between IaaS, PaaS, and SaaS?
• What is AWS?
• What are Regions, Availability Zones, and Edge Locations?
• What is the AWS Shared Responsibility Model?
• What is Scalability?
• What is Elasticity?
• What is High Availability?
• What is Fault Tolerance?