System Design Interview Questions

Vince 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

Aneesh M. - "In the Slack system design interview, I proposed a WebSocket-based architecture for real-time messaging, supported by a network of distributed chat servers. To track user connections and route messages efficiently, I leveraged ZooKeeper as a service registry and designed peer-to-peer communication between servers. For the data layer: • I used PostgreSQL to manage relational data such as users and chat participants. • Cassandra was chosen for high-throughput, scalable message storage with dura"See full answer

Yespm T. - "Clarifying question: When you say users, what specific metric are we talking about?  Answer: we want to increase # of daily active users.  Assume active users are logged in users. Is there a region that we have in mind for this increase? Assume no, we want to think about globally Is there a specific device (mobile vs desktop) ? Assume no Approach: I want to first think about Youtube, its mission and current business at a high level. . Then I want to think about the current ecos"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

Bella R. - "Approach Clarify the question Define deaf --> unable to hear, but can communicate via sign language, lip read and use all other senses Define fire alarm --> for residential use, it notifies occupants of smoke and potential fires and alerts fire department to check in and/or come over Define constraints --> budgetary constraint, design should be user-friendly and convenient Define goals --> get folks out of harm's way quickly and notify fire department to c"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

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

Jacky Y. - "Problem scope: Can this system detect Bot in real-time online or offline? Both. Online traffic: 1M DAU. Latency: 2s. Offline frequency: daily Offline data: 2B activity logs. Data: How do we know a Bot player (Label)? Human label. Imbalance data: reweight, resample. Develop a Bot simulator to generate more data offline for training. Given lower weight to simulator data than human label. Features: Signals from different models online. Log all the features for offline. Propose new features: dail"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

Teja G. - "To design a scalable ticketing system for peak events like Black Friday, you must employ a microservices architecture, implement robust load balancing, leverage caching, and use a combination of NoSQL and relational databases for different data types. Key features also include real-time seat booking, secure payment integration, mobile compatibility with QR code validation, robust admin dashboards for analytics, and integrated marketing tools like promo codes. The system needs to prioritize avail"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

Ramendra S. - "Step 1: Clarifying the Problem Scope We will focus on designing the leaderboard for Dream11 with these assumptions: Registered teams: 100,000 users are actively participating and ranked. Real-time updates: Leaderboard updates frequently as players accumulate points based on live sports events. Multiple leagues: Each user can participate in different leagues, so we will need to maintain a separate leaderboard for each league. Query efficiency: Users frequently"See full answer

B. T. - "The interviewer was interested how the system design would be for files, directories, symbolic links. After proposing my idea, I was asked to print all files for a given path."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

Rjj - "I tried solving this problem and here is the recorded video for the answer. https://www.youtube.com/watch?v=d1tOkeQjyI4 And here is the link to Excalidraw board - https://excalidraw.com/#json=uabNFHcZm5qNh8CInMvyh,Wn9Vf1ZhGdl_iBCQYFkYdw"See full answer

Simon O. - "Functional Requirement Ingest Book Reviews in real time User in the website needs specify title tho search books, return response is the list of reviews on the books. Non Functional Requirement: User get real-time book reviews> It nees to handle the search among 1 million of active users daily"See full answer