System Design Part - I

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1. Server

A server is a computer system that provides data, services, or programs to other computers, known as clients, over a network. In cloud environments like AWS, servers are often virtual and hosted on platforms like Amazon EC2 (Elastic Compute Cloud).

AWS Equivalent: EC2 (Elastic Compute Cloud)

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2. IP Address

An IP address (Internet Protocol address) is a unique string of numbers separated by periods (IPv4) or colons (IPv6) that identifies each computer using the Internet Protocol to communicate over a network.

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3. DNS (Domain Name System)

DNS translates human-friendly domain names (like example.com) into IP addresses that computers use to identify each other on the network.

AWS Equivalent: Route 53

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4. Vertical Scaling

Vertical scaling means increasing the capacity of a single server by adding more CPU, RAM, or storage.

Pros:

• Simple to implement

• No change to application architecture

Cons:

• Limited by maximum hardware capacity

• Single point of failure

• Downtime may be required

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5. Horizontal Scaling

Horizontal scaling involves adding more servers to handle increased load.

Pros:

• Fault-tolerant

• Scalable almost infinitely

• Better for high availability and distributed systems

Cons:

• Requires load balancing

• More complex infrastructure

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6. Load Balancer

A load balancer distributes incoming network traffic across multiple servers to ensure no single server becomes a bottleneck.

Use:

• Improves application availability and reliability

AWS Equivalent: Elastic Load Balancer (ELB)

Load Balancing Algorithms:

• Round Robin: Requests are distributed sequentially.

• Least Connections: New requests go to the server with the fewest active connections.

• IP Hash: Distributes requests based on the client's IP address.

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7. Database Read Replicas

Read replicas are copies of the main database that handle read-only queries to offload traffic from the primary database.

Main Database: Handles write operations and is the source for replication.

AWS Equivalent: Amazon RDS Read Replicas

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8. Caching

Caching stores frequently accessed data in memory to reduce load on servers and databases.

Use:

• Faster response times

• Reduced load on backend

AWS Equivalent: Amazon ElastiCache (Redis or Memcached)

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9. Microservices Architecture

An architectural style where applications are composed of small, independent services that communicate over APIs.

• Each microservice can have its own server (EC2), database (RDS), and load balancer (ELB).

• They are connected via an API Gateway that routes requests to the correct service.

AWS Equivalent: AWS API Gateway

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10. SQS (Simple Queue Service)

SQS is a distributed message queuing service to decouple and scale microservices.

Use:

• Buffers requests between services

Pros:

• Increases fault tolerance

• Smooths traffic spikes

Cons:

• Adds latency

• Increases system complexity

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11. Event-Driven Architecture

An architecture where services communicate by producing and consuming events (messages).

Benefits:

• Loosely coupled

• Scalable and flexible

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12. SNS (Simple Notification Service)

SNS is a pub/sub messaging service for sending notifications to subscribers.

Use:

• Push notifications to services or users

Pros:

• Real-time notifications

• Supports multiple protocols

Cons:

• Not ideal for message durability

• Less control over message processing

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13. Fan-Out Architecture

In this architecture, SNS publishes messages to multiple SQS queues. Each queue is consumed by different services.

Use:

• Efficient parallel processing

• Decouples services

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14. CDN (Content Delivery Network)

A CDN is a network of edge servers that cache content closer to users to reduce latency and improve performance.

Use:

• Serve static assets like images, CSS, JS quickly

AWS Equivalent: Amazon CloudFront

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Conclusion:
This guide introduces essential system design concepts used to build scalable, reliable, and high-performance applications. By leveraging AWS services, these designs become easier to implement and maintain.