System Design Interview Questions

Aekagra S. - "To improve, we first need to understand the problems or opportunities for improvement that are currently present. Assumption: Potential improvement in the recommendation algorithm to make recommendations more pointed Current recommendations are not very specific. Users end up getting frustrated and move away from YouTube Potential improvement in the recommendation algorithm to make sure the user is not just bombarded with one set of videos, but gets varied recommendations to c"See full answer

Kartikeya N. - "Clarifying questions: What is meant by abuse?: Fake, paid reviews Are we looking at any particular country ? : Global Have we seen an increase in the number of fake reviews on Amazon?: Yes Can we quantify the % of fake reviews and how much it has increased in the recent past?: Can’t divulge company data Lets first start with the Vision of Amazon. It is to be the world’s most customer centric company. That is a very lofty and high standards’ Vision. So the problem we are trying to s"See full answer

Varun G. - "Constrain the requirements (The final product should be somewhat like Neptune AI and also enable for A/B testing) Do some back of the envelope calculations Start explaning your system with appropriate architecture diagrams Optimize for scale Answer any questions Wrap-up"See full answer

Vinit N. - "Problem & goal People need a simple way to create documents, collaborate in real time, and never worry about version control or losing work. Traditional word processors were powerful but slow, file-based, and hard to collaborate in. Target users Knowledge workers, students, and teams who write frequently and collaborate often, sometimes across time zones and devices. Core principles Make writing fast, collaboration effortless, and complexity invisible unless the user needs it. **K"See full answer

Theodore (teddy) W. - "So here is what I would do if I had to designing a system to log messages in order involves several considerations, including the choice of software, hardware, storage mechanisms, and scalability. Here’s how I would approach this: 1. Requirements Analysis: Message Format: Define the structure of the messages to log (e.g., text, JSON). Volume: Estimate the expected volume of messages per second. This will help in determining the infrastructure requirements. **Order Guarantee"See full answer

Mathursan B. - "Each song has a playback event that stores information (region, timestamp, etc.) and push to real-time streaming platform and eventually lands into data storage where another service could consume is periodically(say every minute) to compute aggregate counts for the last 7 days. The system can then fetch the top 10 songs by sorting based on playback events using timestamp, optionally filtered by region or genre."See full answer

Berk C. - "High Level Architect Client v API Gateway v Object Storage v Message Queue v Worker v Database Client should can document with a web site or directly with API services. API Gateway should be used for upload document,get document info and state. Object storage should be used for original document and send event to Message Queue for starting. Message Queue is neccessary because there are millions of document should be process each time. Worker can get text from document with OCR. Database shoul"See full answer

Ekta M. - "I would start with some clarifying questions like: Is there a deadline when all these needs to be updated by? Do we have upgrade scripts ready? When do we have change freeze? Once I have these few clarifying answers I would start planning: I would meet with all the teams involved in the upgrades Document any resources downtime during the upgrade create a risk registry along with mitigation plan Roll back plan create a phased rollout plan based on deadline Post upgrade get a"See full answer

Jaehyuk C. - "Q: What ad system do we have (to clarify the limitation of the ads systems and its scope)? -> need context of the advertisement. What signals of ads do we have? pictures, texts, comments, video, etc. What is daily active users on the system? (scalability) Do we need taking actions after detecting it? (further process is needed?) what device do we have ad system? PC, mobile, etc. FR: detect the weapon signals (classification) alert after weapon is detected identify the us"See full answer

Ajay P. - "Designing an evaluation framework for ads ranking is crucial for optimizing the effectiveness and relevance of ads displayed to users. Here's a comprehensive framework that you can use: Define Objectives and Key Performance Indicators (KPIs):** \\Click-Through Rate (CTR):\\ The ratio of clicks to impressions, indicating the effectiveness of an ad in attracting user attention. \\Conversion Rate:\\ The ratio of conversions (e.g., sign-ups, purchases) to clicks, measuring how well"See full answer

Anonymous Mongoose - "The below system design addresses the requirements for a scalable distributed onboarding service, focusing on robust data validation, asynchronous processing, real-time aggregation, and efficient querying of metadata. Core Principles: Asynchronous Processing: Decouple components to ensure high throughput and responsiveness. Scalability & Elasticity: Utilize technologies that can scale horizontally to handle varying loads. Data Durability & Integrity: Ensure no data l"See full answer

Adam L. - "Discussed: Requirements of the system: latency language modality (assume keyboard typing) availability of data (assume cold start) success metric (accuracy of next word predicted?, or minimize false positives? -> accuracy to start) Data collection and processing: design ethical user experiments to collect typed out data design a simple tokenization strategy (word level encoding, character level encoding, byte-pair encodings, and discuss tradeoffs) collect data, and split"See full answer

Alex N. - "Since question asks about pipeline. I assume the question is about metrics across many dimensions not just prediction Model performance. For the ML Model: I can use accuracy, precision, recall, F1 if it is classification model. In case it is regression model RMSE is good metric for many problems. Data: ML system needs good quality data. The system has to track missing data rate. Distribution of features, if there is no drift from original feature distributions during the training. Pipeline h"See full answer

Vijay M. - "Very well done."See full answer

Anonymous Hummingbird - "Clarifying questions: · Is there a specific scenario we are building before? Example: urgent need for a specific type of blood vs building up blood banks proactively. You decide · This would be for mobile/web and integrate into the existing facebook product? Yes Ok before we get started I wanted to discuss the facebook mission: to give people the power to build community and bring the world closer together. I can see how blood donation fits directly into this, enabling blood donation helps"See full answer

Palak A. - "Designing a system to deny services to requests from banned IPs involves integrating real-time IP checking with your service architecture. Here’s a detailed outline of how you can design such a system: System Design Overview The goal is to ensure that your service can efficiently check incoming requests against a list of banned IPs and deny access when necessary. The system will leverage an external API, security.gov.x, to determine if an IP address is blocked or allowed. **Key Compone"See full answer

Ilakiya R. - " Design & Architecture Overview: The system was a scalable, cloud-based web application built to manage customer data and automate service requests. Frontend: React.js: Chosen for its component-based architecture, reusable UI, and fast rendering using Virtual DOM. Backend: Node.js with Express.js: Selected for non-blocking I/O, scalability, and rapid API development. Database: MongoDB: Used for its flexible schema, scalability, and ease of handling unstructured data. Authentication: JWT"See full answer

Javed S. - "One good reason for using the doubly linked list is that to remove an accessed item in the list from its existing position say in the middle of the list and move it to the head, you need to update the previous node's next pointer and the next node's previous pointer. A singly linked list only has next pointers, so removing from the middle would require traversing from the head to find the previous node which requires O(n) time. A doubly linked list allows O(1) removal from any position because w"See full answer