ROLE
Backend
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These are the same questions found in the library, grouped here by the capability each one mainly examines.
1216 questions
Extended questions 501–550 of 1216 on this page.
A · Professional problem solving and implementation31
- Two requests almost simultaneously check that a business object is absent and then both create it; the application-level check-then-write occasionally produces duplicates. How would you use transaction isolation, unique constraints, and conflict handling to preserve the invariant?
- Given a set of records that may exceed memory capacity, process them in batches while allowing the caller to cancel. Describe or implement an interface that bounds memory, locates errors, and starts no new batch after cancellation.
- Several callers read a configuration file whose fields keep growing; older fields may be absent, and new versions must allow unknown extension fields. How would you design a parsing interface so callers can understand defaults, validation errors, and backward-compatibility behavior?
- Latency is normal after a release, but p99 rises gradually after several hours and temporarily recovers after a restart. CPU is steady while connection counts and heap memory slowly grow. How would you break down hypotheses and design low-risk tests?
- A feature works on the corporate network and most home networks, but requests often time out on a particular carrier or under poor connectivity; server error rates do not rise at the same time. How would you isolate causes across client, network path, protocol, and retry behavior?
- Users can edit a profile on a phone while offline and may also edit it on the web. The device must sync when connectivity returns without silently overwriting valuable changes. How would you design versioning, conflict detection, merging, and user confirmation?
- An entry service calls several downstream systems. One noncritical dependency occasionally slows down, exhausting request threads and affecting unrelated features. How would you design timeouts, concurrency isolation, degradation, and recovery?
- A shared library releases a backward-compatible version, but application repositories cannot upgrade promptly because of pinned dependencies, generated code, or different release windows; a security fix remains blocked. How would you design compatibility policy and the dependency-upgrade process?
- An AI assistant repeatedly calls search, databases, and external APIs for a small share of requests, making latency and cost far higher than average. How would you design per-task budgets, stop conditions, idempotency, and auditable execution records?
- During user interviews, people repeatedly suggest buttons, filters, and reminders but rarely describe their goals or blocked situations. How would you adjust question order and wording to distinguish real experiences, stated preferences, and proposed solutions?
- A core service remains within its monthly SLO, but its error budget is being consumed much faster and errors cluster around a recent feature release. How would you decide whether to pause rollout or roll back?
- A new model scores much better on an offline test set, but a small production rollout shows lower task completion for one user group and more complaints. How would you determine where the evaluation set, metrics, or release decision failed?
- An AI assistant retrieves documents from several business systems, where users have different permissions in each. How would you ensure retrieval, caching, summaries, and citations follow source permissions, including after access is revoked?
- A model service used by an AI feature has highly variable latency, causing user requests to exceed the end-to-end deadline. How would you allocate budgets across retrieval, model calls, and post-processing, and design fallbacks after a timeout?
- The same commit passes reliably on a developer's machine but occasionally fails in CI because of time zones, random ordering, shared caches, or parallel races. How would you classify, reproduce, and reduce this nondeterminism?
- A function appears read-only under multithreading, but a formatter it calls uses a shared internal buffer and occasionally mixes results. How would you distinguish thread safety, reentrancy, and statelessness, and decide where to fix the issue?
- The input contains time intervals that may overlap or touch, and callers need to find records covering a given instant. Describe or implement a merge and query strategy, including whether endpoints are inclusive.
- An API adds a new state, but older clients may not recognize it; some must still display the record, while critical operations must reject unknown states. How would you design parsing and defaults so an unknown value is not mistaken for a valid state?
- A streaming service deduplicates events using persistent state and checkpoints. After restoring a checkpoint, the stream may replay events; a crash can also occur between saving the deduplication state and committing the stream offset. How would you make rollback and replay safe while keeping memory bounded?
- The client sees one submission, but the server occasionally creates two identical records. It usually happens after a timeout and retry, with no obvious log error. How would you reconstruct the request timeline and verify where duplication occurs?
- Fresh installations work, but users who upgraded across several versions report missing local drafts. The issue is hard to reproduce, and the server has no corresponding deletion record. How would you preserve evidence and investigate migrations, cache cleanup, and lifecycle callbacks?
- A mobile upload of a large file may be interrupted, and users may retry by tapping again; the system also bills successful processing. How would you design chunks, validation, resumable state, finalization, and the billing point?
- A business-rule correction requires recalculating historical records across several services, but some consumers have already sent notifications or performed external actions. How would you design correction events, impact lists, replay boundaries, and side-effect suppression?
- After a dependency slows down, several callers increase retries at the same time; traffic doubles and the outage spreads. How would you design retry budgets, backoff, jitter, and cross-service coordination?
- A feature is fully launched, but switches created years ago still control several code paths; the team does not know which flags can be removed and relies on memory during rollback. How would you establish flag lifecycles and cleanup ownership?
- A backend API generates TypeScript, Java, and Swift SDKs, but nullable types, enums, and error models are drifting across languages. How would you design the contract source, generation process, and cross-language compatibility tests?
- A production dependency has a different artifact hash from the build associated with its repository tag, and the team cannot confirm it passed the expected CI. How would you establish build traceability, artifact verification, and release authorization?
- New clients use a replacement API, but users upgrade slowly and older versions still account for meaningful traffic; continued support also constrains server evolution. How would you set a support window, capability detection, migration notices, and retirement criteria?
- A user submits a long AI analysis, closes the page, and later checks from another device; the task may call several tools and produce partial results. How would you design task state, cancellation, retry, and result visibility?
- An analytics assistant converts natural language into SQL against business data; a request may induce it to read sensitive columns or run an expensive query. How would you design read-only permissions, query validation, resource limits, and result redaction?
- A model begins returning structured JSON, while mobile, server, and analytics consumers upgrade at different rates; new fields may be absent or enum values may change. How would you define the output contract, handle validation failures, and preserve compatibility?
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E · Collaboration, communication, and influence19
- A colleague repeatedly changes an interface at the last minute but believes they communicated it in chat. Partners still get blocked. How would you give feedback without debating intent?
- You have just taken over a team, and a former peer is now your direct report. Their delivery is strong, but they repeatedly interrupt others in reviews. How would you prepare for and conduct your first feedback conversation?
- Tell me about a time you received feedback that made you uncomfortable. What did you change afterward?
- Did you ever try to break out of your resource or collaboration limits, such as bringing other teams in or asking upward for larger resources? How did you make the case, and what happened?
- Product promises features, engineering promises dates, and operations promises ticket handling, but nobody owns whether customers complete the key task. How would you reset goals with these leads?
- A cross-functional review is shortened to ten minutes, and decision-makers only want to know whether launch can stay on schedule. Your evidence shows two risks with different impact scopes. How would you organize the information so they can make an informed choice quickly?
- You want to push something valuable to the team in the long run that nobody is asking for now. Why do it, how do you persuade others, do you push top-down or bottom-up, and how do you show its value?
- When would you escalate a cross-team problem to a higher level, and how would you describe it?
- Has this solution had any influence outside your organization, such as being adopted by other companies or communities, shared publicly, open sourced, or written up? What is the evidence?
- Your project depends on another team fixing a data defect. They have higher-priority work and no reporting relationship with you, but customers cannot reconcile accounts. How would you make the case and offer decision evidence?
- When you give an overall report upward, how do you present it and win more resources for the team? When different organizations have different goals, how do you connect your team's goals to theirs?
- You want another team to change an interface, but you have no authority over them. What do you do?
- Two teams have committed to quarterly goals, and a critical skill turns out to be held by only one engineer. Both request priority access. How would you negotiate an executable allocation while making the unmet side aware of the cost and review conditions?
- You receive a product requirement and find that building it as written is both costly technically and will give a poor user experience after launch. How do you bring a technical alternative and persuade product to change the requirement? Tell me about a real case.
- When you ask the product and engineering teams for an operations tool, such as coupon configuration or automatic tagging, how do you justify its necessity to engineering rather than asking them every time to run a query by hand and pull the data?
- A partner adds operational and reporting requests every week, calling them included services. Team capacity is affecting other customers. How would you establish facts and negotiate scope or service level?
- Sales promised several customers faster response times, but operations capacity has not increased. How would you renegotiate service levels and eligibility with sales, product, and service teams?
- A cross-department meeting records a decision, but an affected team says it cannot deliver on time. How would you confirm who accepted the decision, which objections remain, and who owns the next step?
- The release owner decides to ship on schedule. The security team says residual risk exceeds its acceptance range, but leadership chooses to continue. How would you record dissent, responsibility, and review conditions and clarify executable scope and escalation boundaries?
No questions in this section match your target. ·