SYSTEM DESIGN BASICS — Save This Post!
Asked in Amazon Microsoft Walmart Interviews!

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System Design separates freshers from
SDE-2 level thinkers. Learn the basics NOW
to stand out in interviews!

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CONCEPT 1: SCALABILITY

What it means: System handles MORE users
without breaking down.

Two types:
Vertical Scaling -> Add more power to 1 server
Horizontal Scaling -> Add MORE servers

Real example: Instagram uses horizontal scaling
with 1000s of servers worldwide!

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CONCEPT 2: LOAD BALANCER

What it means: Distributes traffic across
multiple servers so no single server overloads.

Real example: When you open Amazon.com,
a load balancer sends you to the LEAST busy
server among 1000s of available servers!

Tools: Nginx, AWS ELB, HAProxy

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CONCEPT 3: CACHING

What it means: Store frequently used data
in fast memory to avoid repeated DB calls.

Real example: Twitter caches trending tweets
so millions can see them WITHOUT hitting
the database every single time!

Tools: Redis, Memcached

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CONCEPT 4: DATABASE SHARDING

What it means: Split ONE huge database into
smaller pieces (shards) across servers.

Real example: WhatsApp shards user data by
phone number ranges across different servers!

Why: 1 server CANNOT store billions of users!

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CONCEPT 5: MICROSERVICES

What it means: Break ONE big application into
small independent services.

Real example: Amazon has separate services for
Cart, Payment, Inventory, Shipping — all talking
to each other via APIs!

Why: Easy to scale + update individual parts
without breaking the whole system!

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CONCEPT 6: CDN (Content Delivery Network)

What it means: Store copies of content (images,
videos) on servers CLOSE to the user's location.

Real example: YouTube video loads fast in India
because CDN servers exist IN India, not just US!

Tools: Cloudflare, AWS CloudFront

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CONCEPT 7: MESSAGE QUEUES

What it means: Tasks wait in a queue and get
processed one by one, even under heavy load.

Real example: When you order food on Swiggy,
your order goes into a queue before being
assigned to a delivery partner!

Tools: Kafka, RabbitMQ, AWS SQS

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HOW TO ANSWER SYSTEM DESIGN IN INTERVIEW:

Step 1: Clarify requirements (ask questions!)
Step 2: Estimate scale (users, requests/sec)
Step 3: Draw high-level architecture
Step 4: Discuss database design
Step 5: Discuss scaling + caching strategy
Step 6: Discuss trade-offs

Even freshers get asked 'Design a URL shortener'
or 'Design Instagram' in interviews now!

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FREE RESOURCES TO LEARN MORE:

'System Design Primer' on GitHub (FREE)
ByteByteGo YouTube channel
Gaurav Sen YouTube channel (Hindi/English)

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Build a project using these concepts!
Get FREE source codes:
https://t.me/Projectwithsourcecodes

Save this post for interview prep!

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