AWS Cloud Fundamentals

How Websites Work

When you visit a website, the request flows through multiple layers:
Client → Network → Server

• Client: Your device (laptop, phone) sends a request with its IP address.

• Network: Routers, switches, and DNS servers direct the request through the internet.

• Server: Processes the request and sends the website data back to the client.

💡 Example: Netflix (built on AWS) delivers content globally using AWS servers.

---

What is Cloud Computing?

Cloud computing is the on-demand delivery of IT resources with pay-as-you-go pricing.

• Compute power, database storage, and applications on demand.

• Scalability: Instantly access more resources when needed.

• AWS Infrastructure: AWS owns and maintains the network-connected hardware for these services.

Key Benefits:

• No need to own hardware.

• Access resources instantly.

• Only pay for what you use.

---

Cloud Deployment Models

1. 🌐 Public Cloud:

   • Resources owned by third-party providers (AWS, Google Cloud, Azure).

   • Delivered over the internet.

   • Example: Hosting apps on AWS servers.

2. 🔒 Private Cloud:

   • Used by a single organization, offering better control and security.

   • Ideal for sensitive data.

3. 🔗 Hybrid Cloud:

   • Combines on-premises infrastructure with cloud resources.

   • Used to protect sensitive data while leveraging cloud benefits.

   • Example: Banks using on-prem for sensitive data and cloud for customer services.

---

AWS Cloud Use Cases

AWS enables you to build sophisticated, scalable applications across industries:

• Enterprise IT: Backup, storage, big data analytics.

• Web Hosting: Websites, mobile, and social apps.

• Gaming: Build and scale game servers with ease.

💡 Example: Netflix uses AWS for reliable, scalable content delivery.

---

AWS Global Infrastructure

AWS is spread globally for high availability and low latency.

AWS Regions:

• Clusters of data centers worldwide.

• Named like us-east-1, eu-west-3.

• Most AWS services are region-scoped.

• How to choose a region:

  • Compliance: Data governance regulations.

  • Proximity: Reduced latency for nearby users.

  • Service Availability: New services may be region-specific.

  • Pricing: Costs vary by region.

Availability Zones (AZ):

• Each region has 3-6 AZs (usually 3).

• Each AZ consists of multiple data centers with:

  • Redundant power

  • Networking and connectivity

• Isolated from disasters but interconnected with low-latency networks.

Point of Presence (PoP):

• 400+ PoPs across 90+ countries.

• Improves content delivery speeds (via CloudFront CDN).

---

AWS Global and Region-Scoped Services

Global Services:

• IAM: Identity and Access Management.

• Route 53: DNS service.

• CloudFront: Content delivery network.

• WAF: Web Application Firewall.

Region-Scoped Services:

• EC2: Infrastructure as a Service.

• Elastic Beanstalk: Platform as a Service.

• Lambda: Function as a Service.

• Rekognition: Software as a Service.

---

AWS Pricing Model

AWS uses a pay-as-you-go pricing structure with three main categories:

1. 💻 Compute:

   • Pay for the time your EC2 instances run.

   • Billing stops when instances are terminated.

2. 📦 Storage:

   • Pay for the data you store (e.g., S3 buckets).

3. 🔗 Data Transfer:

   • IN → Free.

   • OUT → Charged based on region and amount of data.

Cost Benefits:

• Lower TCO: No upfront hardware costs.

• Massive economies of scale: AWS reduces prices as it grows more efficient.

• Flexible scaling: Only pay for what you use.

---

Additional Key AWS Concepts

Elasticity vs. Scalability:

• Elasticity: Automatically adds or removes resources based on demand.

  • Example: Auto-scaling EC2 instances.

• Scalability: Increases or decreases resources manually.

  • Example: Adding more EC2 instances as traffic grows.

High Availability (HA) vs. Fault Tolerance (FT):

• High Availability: Ensures minimal downtime by using redundant systems.

  • Example: Multi-AZ deployments.

• Fault Tolerance: Automatically recovers from failures without service interruption.

  • Example: S3 with cross-region replication.

AWS Support Plans:

1. Basic: Free, includes customer service and community forums.

2. Developer: For experimenting or testing environments.

3. Business: For production workloads, 24/7 support.

4. Enterprise: For mission-critical workloads, dedicated TAM support.

AWS Well-Architected Framework:

• Operational Excellence: Efficiently run and monitor systems.

• Security: Protect systems and information.

• Reliability: Recover quickly from failures.

• Performance Efficiency: Use resources efficiently.

• Cost Optimization: Reduce unnecessary costs.

---

Shared Responsibility Model

AWS uses a shared responsibility model for security and compliance:

AWS Responsibility (Security of the Cloud):

• Protecting the infrastructure.

• Managing the physical security of hardware.

• Securing services like S3, EC2, and RDS.

Customer Responsibility (Security in the Cloud):

• Managing access control (IAM).

• Encrypting sensitive data.

• Configuring security groups and firewalls.

• Patching OS and applications.

💡 Example:

• AWS protects the data centers, while you configure IAM roles and security groups.

---

Quick Revision Table

---