USE CASE

External job interviews

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

1324 questions

Questions 51–100 of 1324 on this page.

A · Professional problem solving and implementation50

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
A repository accepts external contributions, and CI runs build scripts, reuses caches, reads test credentials, and produces release artifacts. How would you separate untrusted execution, credential permissions, and cache boundaries so code cannot read secrets or poison trusted artifacts?Engineering systems
Cloud costs keep rising and finance asks for cuts while teams are improving reliability. How would you find savings without shifting risk elsewhere?Engineering systems
A long-lived credential is shared by several services. Security requires prompt rotation, but all dependents cannot be stopped at once. How would you proceed?Quality, security, and safety
How do you identify and record technical debt and pay it down without stopping business delivery? Which debts are worth paying and which can be left for good, and how do you judge?Engineering systems
Your solution depends on a lower-level service or library. If it changes substantially, how would you migrate, fall back to a version that preserves core features, or replace it?Engineering systems
The root cause of an incident is still unknown, but business stakeholders ask when service will recover. How would you update them, communicate uncertainty, and avoid misleading commitments?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
Some production resources differ from their declared configuration, including undocumented emergency fixes. How would you distinguish intentional changes from unexplained differences, assess the risk of overwriting state, restore trust, and prevent recurrence?Engineering systems
A release must reach thousands of runtime nodes with varying versions and network conditions. How would you design rollout batches, health checks, and pause criteria?Engineering systems
After a release goes wrong, the team says “we can roll back.” How would you check that this is true and not just a line in the plan?Engineering systems
A company’s frontend projects live in separate repositories, and someone proposes merging them into a monorepo. How would you decide whether to do it, and how would you validate it in steps?Engineering systems
The application can be rolled back, but a database migration removed an old field and the previous version can no longer start. How would you redesign release order and rollback?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
You take over a module that is about to ship and has very low test coverage, and time is short. How do you decide which tests to add first, and how do you explain that order to the team?Quality, security, and safety
The framework allows concurrent background UI updates, but a slow response occasionally overwrites a newer selection. How would you design concurrent state updates?Coding and abstraction
A complex form has field validation, cross-field rules, and server errors that overwrite one another during edits. How would you divide framework state from business state?Coding and abstraction
Several pages share server data and framework caching reduces requests, but stale results appear after users switch accounts. How would you design cache keys and invalidation boundaries?Coding and abstraction
After a frontend framework upgrade, compilation succeeds, but render timing, default caching, or side-effect order changes. How would you verify product behavior remains correct?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 feature adds startup dependencies and cold start becomes much slower on low-end devices, while high-end metrics remain normal. How would you prioritize optimization?System design
A user edits offline and queues several changes. When connectivity returns, the token has expired and some requests may already have reached the server. How would you design reauthentication, idempotency, and conflict handling?System design
After code changes, the build system sometimes misses affected apps and sometimes rebuilds the entire repository. How would you validate the dependency graph and cache invalidation rules?Engineering systems
One repository contains multiple teams and production deployment config, but code-owner rules do not cover temporary admins and automation accounts. How would you review permission and approval boundaries?Engineering systems
Two product packages form a dependency cycle, and splitting them creates a need to share domain types. How would you change the boundaries without hiding the cycle in a new shared package?Engineering systems
A team decides to split a large repository, but history, CI, package releases, and ownership are connected. How would you sequence the migration?Engineering systems
In a monorepo, shared packages are casually changed by one team, while consumers discover behavior changes only after upgrading. How would you establish ownership and compatibility contracts?Engineering systems
Packages have very different release cadences, but shared version numbers force unrelated teams to release together. How would you design versioning and release policy?Engineering systems
The repository has hundreds of packages and full CI is slow. The team wants to test only “affected” areas. How would you prove selective testing does not miss critical dependencies?Engineering systems
After an async task starts, the caller immediately mutates an input object, and results sometimes change. How would you determine whether this is shared mutable state, copy semantics, or an ownership issue?Computer-science foundations
Two usernames that look identical are treated as different, or distinct spellings are treated as the same. How would you analyze Unicode normalization and identity comparison?Computer-science foundations
A core flow passes mouse testing, but keyboard or screen-reader users cannot complete it. How would you include accessibility in release gates?Quality, security, and safety
A critical user journey across several pages and services regresses often. How would you define the scope and priority of automated tests?Quality, security, and safety
A user requests deletion of personal data, but some records have reached backups, analytics warehouses, and downstream systems. How would you design a verifiable deletion process?Quality, security, and safety
A widely used dependency is disclosed as critically vulnerable, but upgrading may introduce compatibility issues. How would you sequence the response?Quality, security, and safety