TOPIC

System design

These are the same questions found in the library, grouped here by the capability each one mainly examines.

88 questions

Questions 1–50 of 88 on this page.

A · Professional problem solving and implementation49

A generative feature produces good answers, but peak latency and per-request cost exceed the product budget. How would you determine whether the cause is the model, context, retrieval, or call chain?AI engineering
Your company wants an internal knowledge assistant, and document permissions change as people move around. How would you make it answer with evidence while keeping it from exposing what a user should not see?AI engineering
A new index speeds up queries, but write latency and storage growth worsen noticeably. How would you decide whether to keep it?Computer-science foundations
A request calls four downstream services, each using a full two-second timeout. End-to-end tail latency is high, and clients continue work after the response is no longer useful. How would you propagate deadlines and budgets?System design
Overall capacity is sufficient after sharding, but a few tenants still overload hot keys. How would you reassess the partition strategy?System design
An old system keeps accumulating new business and is becoming hard to maintain. How would you create an adapter boundary between old and new systems so legacy rules and data models do not spread into new code? Explain the migration steps and any compromises or risks you would accept.Engineering systems
Tell me about an architecture upgrade. Why did it have to be upgraded rather than patched further, what challenges came up during migration, how did you keep the business running, and did the benefit materialize?Engineering systems
For a given capability, how do you decide between building it, adopting open source, or buying it? How do building and open source differ in cost, control, maintenance, and risk, and when should you switch from one to the other?Engineering systems
In the technical area you work in, how is the industry developing? Is your solution adapting to that trend or going against it?Engineering systems
What technical gains did this project bring? How do you measure them, and what complexity and maintenance cost did you pay for them?Engineering systems
A user signs in within one child app but loses permissions or session state when switching to another. How would you design the boundary for shared auth context?Engineering systems
One app emits an “order completed” event, but other modules interpret it differently, causing duplicate requests and divergent page state. How would you define a cross-app event contract?Engineering systems
Users report a blank page after navigating across apps, while each team’s monitoring appears healthy. How would you establish end-to-end observability?Engineering systems
After independently developed apps are integrated, styles collide, themes differ, and overlays are clipped. How would you choose a style-isolation strategy?Engineering systems
Several frontend modules build independently, but releases still require coordination. What evidence would show they have a real independent delivery boundary?Engineering systems
A large frontend makes parallel delivery difficult, but splitting it into several apps at once is risky. How would you plan an incremental migration and judge each step?Engineering systems
If a micro-app fails at startup, users cannot access other modules. How would you isolate the failure and, if needed, disable noncritical features to keep the rest available?Engineering systems
Several child apps depend on different React and component-library versions, causing both duplicate downloads and runtime conflicts. How would you govern shared dependencies?Engineering systems
Several child apps share the browser address bar, but back/forward, deep links, and login redirects behave inconsistently. How would you define a routing contract?Engineering systems
Two services write directly to the same business table, and an immediate shutdown is impossible. How would you gradually establish a single data owner?System design
An order is updated successfully, but a cross-service report reflects it minutes later. The product asks for “real-time status.” How would you define and implement consistency expectations?System design
A cross-service flow includes payment, inventory reservation, and shipment. How would you define compensations and irreversible boundaries when later steps fail?System design
Incidents recur at service boundaries. Each team can show its service is healthy, but nobody owns end-to-end recovery. How would you repair accountability?System design
Several services have separate owning teams, yet a small change often requires three or four teams to release together. How would you assess whether the service boundaries have failed?System design
A new external service will access user data and trigger internal actions. How would you perform a lightweight but effective threat model?Quality, security, and safety
How should the permission system of a large operations back office be designed? How do you organize roles, data scope, approvals, and audit, and how do you keep it from getting out of control as permissions multiply?System design
How would you design an article editing and publishing system? How should state and data be organized for drafts, review, scheduled publishing, multi-channel distribution, and edits after publication?System design
Issuing a coupon after payment used to run synchronously, and it is being changed to an async queue with retries. Review this change: which failure sequences worry you most, and what would you rehearse before release?System design
From a file or the network to picture and sound playing, what stages does a video go through? How do decoding, audio-video sync, stutter, and hardware acceleration each affect the experience?Computer-science foundations
How would you design an online audio or video editor? How should the timeline, assets, non-destructive editing, preview, and final export each be designed?System design
How would you design a platform where operations staff build campaigns and game mechanics themselves? How do you abstract campaigns, mechanics, rules, and features into configurable parts, and how do you keep a configuration correct once it goes live?System design
Before drawing any architecture diagram, which few numbers would you use to decide whether a service should be split or cached? Use a service you know to explain.System design
How would you design a document system for real-time multi-user editing? When several people edit the same passage at once, how do you guarantee eventual consistency, and how do you merge after offline edits?System design
From an engineering view, how do you estimate the overall cost of a system? How are storage and compute costs each calculated, and which grow linearly with scale and which do not?System design
When the business operates across several countries and regions and user data must flow across borders, how do you solve data compliance in systems and processes, and how do you judge and decide in gray areas where the rules are unclear?System design
The local database has updated, but syncing the cache or sending a downstream message fails. How would you make the systems converge and handle retries, compensation, or manual recovery?System design
A major promotion or international launch may increase traffic fivefold next year. Starting from the current architecture, how would you check for bottlenecks in the gateway, critical request flows, storage, and machine resources? How would you phase the work, staff it, and validate your assumptions?System design
How would you design a product where a person and an AI write together? How are the AI's edits shown, accepted, or rejected, and how are conflicts handled when both edit at once?System design
How would you design an immersive audio and video feed so that swiping up and down has almost no waiting? How do you balance preloading, player reuse, memory, and data?System design
Design a collaboration product that supports large-file uploads with resumability, where files must be validated and scanned before other members can access them. What constraints would you clarify, and how would you design upload, temporary storage, scanning, publication, permissions, and cleanup boundaries?System design
How would you design a large-model chat system? How do you handle streamed output, multi-turn context, history, interruption, and retries, and how do you control cost and latency?System design
How do the costs of a recommender system add up, including retrieval, ranking, feature serving, storage, and experimentation? How would you trade effect against cost?System design
How would you design an invitation-based viral marketing campaign? How do you design invitation relationships, reward payout, abuse prevention, and effect evaluation?System design
To build an online editor like Doc, PPT, or PS, how do you design the core data model and rendering? How do you handle undo and redo, selection, and performance on large files?System design
How would you design a real-time risk control system? How do rules, features, models, and manual review work together, and how do you trade false blocks against misses?System design
How would you design a search system? How do indexing, retrieval, and ranking divide the work, how are Chinese segmentation and features built, and how do you judge how good the search is?System design
How should the loading and request strategy of streaming media be designed so it starts fast and does not stall? How do you trade off segmenting, adaptive bitrate, preloading, and caching?System design
Tell me about a project you worked on. Why did you choose that technical approach over the others, how was the decision made, and what were its pros and cons?System design
How should coupons, discounts, and flash sales integrate with a trading system without slowing the core transaction flow? How would you calculate, combine, and reconcile discounts?System design

B · Business understanding and domain modeling1

How does your own business model interact with the industry's or a partner's common model? When fields, definitions, or concepts do not line up, how do you handle it?Data model