System Design Interview Questions

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

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

Alvis F. - "Requirements and Goals Primary Goal:Store key-value pairs in a cache with efficient access (reads/writes). Evict items based on a certain “rank,” which might reflect popularity, frequency, or custom ranking logic. Functional Requirements:Put(key, value, rank): Insert or update a key with the given value and rank. Get(key): Retrieve the value associated with the key if it exists. Evict(): If the cache is at capacity, evict the item with the lowest rank (or according"See full answer

Reno S. - "1. Requirements Analysis Functional Requirements Video streaming with multiple quality levels Content browsing and search Continue watching functionality Content recommendations Non-Functional Requirements Low latency video delivery (<2s startup time) High availability (99.99% uptime) Scalability to handle millions of concurrent streams API response time < 100ms 2. Microservices Architecture Core Microservices Content Service Content metadata mana"See full answer

Ramendra S. - "Step 1: Clarifying the Problem Scope Assumptions and basic system requirements: Cashless payments: The machine supports cashless payment methods like credit cards, mobile wallets, or NFC-based payments (e.g., Apple Pay, Google Pay). Multiple candy options: The machine offers different types of candy. Inventory management: The system tracks the stock of candy in real-time. User interface: A display screen for users to select the type of candy, make payments, an"See full answer

Precious H. - "Firstly, In designing a denoising system for sounds, I would start by clarifying the type of noise either stationary or non-stationary and application constraints which are the latency, scalability, accuracy and deployability. For real-time systems like Google meet, I will prefer a hybrid DSP + ML model like RNNoise. For batch processing like YouTube audio enhancement, a deep learn-based system such as Demucs or SEGAN would work well. Then I will need to evaluate how well the system improves aud"See full answer

Istvan K. - "Thanks you for sharing insight about the app which I would liek to summarize in 2 structures: functional 2 technical requirement. Requirements: Functional requirement: Able to share messages, siles , and other content like photos, sounds Create groups for conversaion Size: 500 million users, 50m DAU -> 500M active chats daily Files not stored in the system but is can be shared.. Integaration with other APPs Technical requirement: Availability: Can you help me to understand the a"See full answer

BriskD - "I watched a couple of videos like this, one of them by Exponent staff (I think). It was disappointing that the architecture diagram and the walkthrough was a general layered architecture that you can apply to any backend system. I was wondering if there are videos that can be considered a reference material to watch, learn and improve on the tech (sys design) skills, and not so much about the soft skills."See full answer

Ketshi B. - "Clarifying questions When we say signals do you mean just features that are fed into the ML model that decide how the content should be ranked? Is newsfeed the front page of fb app. Can you expand what you mean by relevance? User journey User enters blue app.. Newsfeed is the first thing they see. User either continues on newsfeed ie scrolls through it or moves to a separate part of fb As they are scrolling they may see contents from friends, creators and ads, or other pages that they have been"See full answer

Scott S. - " To clarify on what we are trying to solve for and get the definition of a distributed scheduler straight . So A Distributed Scheduler refers to a system that can handle job scheduling and execution in a scalable and fault-tolerant manner by distributing the workload across multiple servers or nodes. we will make some assumptions with the design , as follows: we will assume 10,000 QPS for job submissions and should be able query for jobs status . Job execution should have minimal latency"See full answer

anush - "@Jacob, your videos are really good and helpful. I want to know about the tool, you use for explaining the design in the videos."See full answer

A B. - "Great explanation on each of the components and their use. During the interview would a PM candidate be expected to go in-depth for capacity estimation (e.g. storage estimation, bandwidth estimation etc.?)"See full answer

Kartikeya N. - "C : Okay. So I would want to start with knowing what is the product for which we have to build a recommendation system. I : This is a photo sharing product. C : Okay. So is this something on the lines of Instagram? I : Yes C : Okay. And are we a new product co or we have some current product built already? I : You can assume yourself. C : Okay. Is there any demography or country we are targeting? I : No, this is a global product C : Okay. So, the biggest goal of any product recommendation system"See full answer

Chitapuram N. - "Since there is a need for the data to be accurate and consistent without any latency to allocate a spot, can't the data be synchronously synced to replicas after every write as the number of writes are not many per min, instead of read lock phenomena Let me know if i am on a wrong thought here."See full answer

dreamingincode - "In the API design, the interviewer is switching between RPC style (operation based endpoints) and REST style (resource oriented). Sticking to one convention and explaining why it is preferred over the other e.g. REST if the twitter domain maps nicely to resources e.g. /tweet or /follower or /user would help to create a more consistent and unified API. It would make it easier for clients to integrate with the API as well."See full answer

Rahul .. - "''' Problem Statement: Design a simplified Robinhood-like stock trading platform. Requirements: User Management: createuser(userid, name, initial_balance): Create user with cash balance getbalance(userid): Get user's cash balance deposit(user_id, amount): Add funds to account withdraw(user_id, amount): Withdraw funds (if sufficient balance) Stock Operations: updatestockprice(symbol, price): Update current price of a stock getstockprice(symb"See full answer