First design walkthrough (URL shortener) in HLD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the main purpose of a URL shortener system?

A URL shortener converts a long URL into a shorter, easy-to-share link that redirects users to the original long URL.

beginner

Name two key components of a URL shortener system.

1. A service to generate and store short URLs mapping to long URLs. 2. A redirect service that sends users from the short URL to the original long URL.

intermediate

Why is it important to handle collisions when generating short URLs?

Because two different long URLs might generate the same short URL code, causing incorrect redirection. Handling collisions ensures each short URL uniquely maps to one long URL.

intermediate

What is a common technique to generate short URL codes?

Using a base62 encoding of a unique ID or hashing the long URL and encoding part of the hash to create a short, alphanumeric code.

advanced

How can a URL shortener system scale to handle millions of requests?

By using caching for popular URLs, load balancing across servers, distributed databases for storage, and asynchronous processing for analytics.

What does a URL shortener primarily do?

A Converts long URLs into shorter ones for easy sharing

B Encrypts URLs for security

C Blocks malicious URLs

D Stores user passwords

A URL shortener creates short links that redirect to long URLs.

Which encoding is commonly used to create short URL codes?

A Base10

B Base62

C Base16

D Base8

Base62 uses digits, uppercase and lowercase letters, making short codes compact.

What is a key challenge when generating short URLs?

A Handling collisions

B Encrypting URLs

C Compressing URLs

D Translating URLs

Collisions occur when two URLs map to the same short code, which must be avoided.

Which component redirects users from short URLs to original URLs?

A Database service

B Authentication service

C Analytics service

D Redirect service

The redirect service handles user requests and sends them to the original URL.

How can caching help a URL shortener system?

A By encrypting URLs

B By compressing URLs

C By storing popular URL mappings to reduce database load

D By blocking spam URLs

Caching popular URLs speeds up redirection and reduces database queries.

Explain the main components and flow of a URL shortener system.

Think about how a long URL becomes a short one and how users get redirected.

Describe strategies to ensure scalability and reliability in a URL shortener design.

Consider how to handle many users and keep the system fast and accurate.