Interview Questions and Answers
Intermediate / 1 to 5 years experienced level questions & answers
Ques 1. Design a URL shortening service like bit.ly.
The system would involve a database to store mappings of short URLs to original URLs, a front-end for user input, and a back-end to handle requests by redirecting to the original URL.
Example:
A user shortens 'https://www.example.com/page123' to 'http://bit.ly/xyz'.
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Ques 2. Design a chat application like WhatsApp.
The system involves a messaging server to handle real-time communication, a database to store messages, and end-to-end encryption for security.
Example:
User A sends a text message to User B, and the message is delivered in real-time.
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Ques 3. Create a ride-sharing system like Uber.
The system involves a mobile app for users and drivers, a backend to manage ride requests, and a geospatial database to match riders with drivers.
Example:
A user requests a ride, and the system matches them with a nearby available driver.
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Ques 4. Design a recommendation system for an e-commerce platform.
The system uses collaborative filtering, content-based filtering, or hybrid methods to recommend products based on user behavior and preferences.
Example:
A user who bought a camera may receive recommendations for related accessories.
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Ques 5. Design an authentication and authorization system.
The system involves user authentication through credentials, token-based authorization, and proper session management to ensure secure access to resources.
Example:
A user logs in with valid credentials and receives a token for subsequent authorized requests.
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Ques 6. Build a social media analytics system.
The system collects and processes data from various social media platforms, uses a storage system for analytics, and provides insights based on user engagement.
Example:
An organization tracks the performance of its social media campaigns using analytics provided by the system.
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Ques 7. Create a job scheduling system.
The system manages and schedules jobs, allocates resources, and ensures efficient utilization of computing resources.
Example:
A user submits a batch of tasks, and the system schedules and executes them based on priority and available resources.
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Ques 8. Build a recommendation system for music streaming.
The system uses collaborative filtering, genre analysis, and user preferences to recommend music based on individual tastes.
Example:
A user listens to a few songs, and the system suggests additional tracks matching their music preferences.
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Ques 9. Create a caching system for a web application.
The system caches frequently accessed data, utilizes expiration policies, and ensures cache consistency for improved performance.
Example:
Web application fetches user profiles from the cache instead of the database for faster response times.
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Ques 10. Build a notification system for a mobile app.
The system sends push notifications, manages user preferences, and ensures delivery reliability with appropriate queuing mechanisms.
Example:
A user receives a real-time notification when a new message is received in the app.
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Ques 11. Build a content recommendation system for a news platform.
The system uses natural language processing, user behavior analysis, and collaborative filtering to recommend articles based on user interests.
Example:
A user reads news articles, and the system suggests related articles from various categories.
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Ques 12. Design a high-throughput logging and monitoring system.
The system collects logs, metrics, and traces from various services, stores them centrally, and provides tools for monitoring and analysis.
Example:
System administrators monitor server performance and troubleshoot issues using logs and metrics provided by the system.
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Ques 13. Build a system for managing user preferences and personalization.
The system involves storing and updating user preferences, using machine learning algorithms for personalized recommendations, and ensuring data privacy.
Example:
A user customizes settings in an app, and the system tailors content and features based on those preferences.
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Experienced / Expert level questions & answers
Ques 14. Create a distributed cache system.
The system can use a consistent hashing algorithm to distribute keys across multiple cache nodes, and a mechanism to handle cache misses by fetching data from the main storage.
Example:
When a node receives a cache miss, it fetches the data from the main database and stores it in the cache for future requests.
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Ques 15. Build a content delivery network (CDN).
The system includes edge servers strategically placed worldwide to cache and deliver static content, reducing latency and improving performance.
Example:
A user in Asia requests an image, and it's served from the nearest edge server instead of the origin server.
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Ques 16. Design a scalable news feed system like Facebook's.
The system comprises a feed generation service, a storage system for user posts, and algorithms to rank and personalize the feed based on user interests.
Example:
User sees posts in their feed based on relevance and recency.
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Ques 17. Build a fault-tolerant file storage system.
The system can replicate data across multiple servers, use erasure coding for data durability, and implement techniques like sharding for better performance.
Example:
Even if one server fails, the system ensures data availability and integrity.
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Ques 18. Create a scalable video streaming service like Netflix.
The system includes a content delivery network, video encoding/transcoding servers, and a recommendation engine to provide a seamless streaming experience.
Example:
A user selects a movie, and the system streams it in high quality without buffering.
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Ques 19. Design a distributed file system.
The system involves a master server for metadata, chunk servers for storing data, and a replication mechanism for fault tolerance.
Example:
A user uploads a large file, and it gets distributed and replicated across multiple servers for reliability.
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Ques 20. Design a real-time stock trading system.
The system includes a trading engine, order matching algorithm, and a distributed database for storing real-time stock prices and transaction history.
Example:
A user places a stock order, and the system executes it in real-time based on market conditions.
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Ques 21. Design a video conferencing system.
The system involves audio/video processing, real-time communication, and scalability to support multiple participants in a conference.
Example:
Multiple users join a video call, and the system ensures smooth communication with low latency.
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Ques 22. Design a content moderation system for a user-generated platform.
The system uses machine learning models, user reports, and manual review to identify and filter inappropriate content.
Example:
A user posts content, and the system automatically detects and removes content violating community guidelines.
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Ques 23. Design an e-commerce search engine.
The system involves indexing products, ranking algorithms, and handling user queries with efficient search and filtering capabilities.
Example:
A user searches for 'laptops,' and the system returns relevant products with sorting options.
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Ques 24. Design a scalable IoT (Internet of Things) platform.
The system involves device connectivity, data processing, and storage for managing a large number of IoT devices and their data.
Example:
Sensors in smart home devices send data to the platform, and the system processes and stores the information for analysis.
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Ques 25. Design a scalable message queue system.
The system involves message producers, queues, and consumers, with features like message persistence, load balancing, and fault tolerance.
Example:
Services in a microservices architecture communicate by sending messages through the queue.
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Ques 26. Create a collaborative document editing system like Google Docs.
The system involves real-time collaboration, version control, and conflict resolution mechanisms to enable multiple users to edit a document simultaneously.
Example:
Several users edit a document together, and changes are reflected in real-time across all collaborating users.
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Ques 27. Design an online multiplayer gaming system.
The system involves game servers, matchmaking algorithms, and real-time communication for a seamless multiplayer gaming experience.
Example:
Players from different locations connect to the game server and engage in a multiplayer game with low latency.
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Ques 28. Design an event-driven architecture for a financial trading system.
The system uses events to trigger actions, ensuring real-time updates and responses to market changes in the financial trading domain.
Example:
A change in stock prices triggers automatic buy/sell orders in response to predefined trading algorithms.
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Ques 29. Create a system for real-time analytics on a streaming data source.
The system involves data ingestion, processing, and analytics in real-time to provide insights on streaming data.
Example:
Sensor data from IoT devices is continuously analyzed to detect anomalies and trigger alerts in real-time.
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Ques 30. Design a distributed task scheduling system.
The system manages the distribution and execution of tasks across multiple nodes, considering load balancing and fault tolerance.
Example:
A cluster of servers schedules and executes tasks in parallel to efficiently process a large workload.
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