Questions 1–200 of 353
What is the difference between horizontal and vertical scaling, and when would you use each?
Asked in 7 of 942 interviews · last asked Oct 22 · Concept · Mid-level
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Vertical scaling gives one server more CPU, memory, or storage. Horizontal scaling adds more servers to share the work. I use vertical scaling when a larger server can meet demand without changing the system much. I use horizontal scaling for growth beyond one server or better availability, if the workload can be split.
- Vertical scaling is simpler, but has hardware limits and may require downtime.
- Horizontal scaling adds coordination, load balancing, and data management complexity.
- More servers improve availability only when the system can handle server failures.
What the interviewer checks: The interviewer checks whether you can choose a scaling approach based on growth, availability, and system complexity.
Other ways it was asked
- “What is the difference between vertical and horizontal scaling?”
- “What is the difference between horizontal and vertical scaling?”
- “What is the biggest difference between horizontal scaling and vertical scaling?”
What is idempotency, and when is it useful?
Asked in 6 of 942 interviews · last asked Oct 15 · Concept · Mid-level
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Idempotency means repeating the same operation has the same intended effect as doing it once. It makes retries safe when a request times out or a message is delivered again. For example, a payment API can use an idempotency key to avoid charging twice for the same payment request.
- Idempotency concerns the effect on system state; repeated calls may return different responses.
- Setting a value is usually idempotent; incrementing it is not.
- Idempotency keys identify retries of one operation, not separate operations with identical data.
- Duplicate detection must handle concurrent requests safely.
What the interviewer checks: The interviewer is checking whether you understand safe retries and how to prevent duplicate effects.
Other ways it was asked
- “What does idempotency mean?”
- “What is idempotency?”
- “What is idempotency, and where is it useful in a software system?”
If a service restarts and an external service resends the same message for a 50,000-peso payment, how would you design the system so the recipient is not credited 100,000 pesos?
Asked in 6 of 942 interviews · last asked Oct 15 · Design · Senior
Show answer
I would make payment processing idempotent using a stable payment ID from the sender. In one database transaction, I would record that ID with a unique constraint and credit 50,000 pesos. A retry with the same ID would not credit again, even after a restart. I would acknowledge the message only after the transaction commits.
- Store processed payment IDs durably, not only in memory.
- The unique constraint blocks concurrent duplicates; the transaction keeps the payment record and credit together.
- Use the same payment ID across retries, not a new ID for each delivery.
- Check payment state so late events cannot repeat a credit or move a settled payment backward.
What the interviewer checks: The interviewer checks whether you can prevent duplicate credits across retries, crashes, and concurrent processing.
Other ways it was asked
- “If a service restarts and an external service resends the same message for a 50,000-peso payment, how would you prevent the recipient from receiving 100,000 pesos?”
- “If an external service resends the same 50,000-peso payment message after your service restarts, how would you prevent the recipient from receiving the payment twice?”
- “How would you design the system so that if a service restarts and an external service resends the same 50,000-peso credit message, the customer is not credited twice? How would you handle a late event indicating that the transaction is already settled or in an intermediate state?”
What are Veritas clusters?
Asked in 3 of 942 interviews · last asked Dec 4 · Concept · Mid-level
Other ways it was asked
- “What is a Veritas cluster?”
How would you design an application and its services to scale as the user base grows?
Asked in 3 of 942 interviews · last asked Sep 21 · Design · Senior
Other ways it was asked
- “What does application scalability mean, and how would you design an application to scale?”
- “How would you design an application to scale?”
- “If you wanted to scale the application to 100,000 users, how would you ensure the architecture and services support scalability?”
What is a cascading failure?
Asked in 2 of 942 interviews · last asked Oct 6 · Concept · Mid-level
Other ways it was asked
- “How can you solve cascading failures?”
How does the circuit breaker pattern work?
Asked in 2 of 942 interviews · last asked Oct 9 · Concept · Senior
Other ways it was asked
- “Can you explain the circuit breaker pattern?”
How would you prevent duplicate SMS messages when processing repeated requests?
Asked in 2 of 942 interviews · last asked Jul 27 · Concept · Senior
Other ways it was asked
- “How would you prevent duplicate SMS messages from being sent?”
How would you design idempotency for a POS/payments endpoint, including the database schema and API contract, so retries don't create duplicate charges?
Asked in 2 of 942 interviews · last asked Oct 22 · Design · Senior
Other ways it was asked
- “In a high-throughput REST API, how would you implement idempotency for POS or payments so retries don't double-charge?”
How would you prepare an ecommerce startup's architecture for a high-traffic event like Black Friday?
Asked in 2 of 942 interviews · last asked Oct 23 · Scenario · Senior
Other ways it was asked
- “How would you prepare an ecommerce platform to support 2,000,000 users or handle Black Friday traffic?”
If a downstream service is slow or unavailable, how would you prevent your application from failing?
Asked in 2 of 942 interviews · last asked Oct 23 · Scenario · Senior
Other ways it was asked
- “How would you protect a mobile app when a downstream service becomes slow but does not fail?”
What is a load balancer?
Asked in 2 of 942 interviews · last asked Feb 22 · Concept · Junior
What is redundancy?
Asked in 2 of 942 interviews · last asked Aug 14 · Concept · Junior
Other ways it was asked
- “What is data redundancy?”
How would you design microservices to handle 2.5 million requests while keeping a changing dataset up to date across services?
Asked once · last asked Aug 22 · Design · Senior
Other ways it was asked
- “How would you design microservices to handle 2.5 million requests?”
- “How would you design the software infrastructure for microservices that use a shared dataset and handle 2.5 million requests per second?”
- “How would you design the software infrastructure for microservices that process a shared dataset and handle 2.5 million requests per second?”
Can you explain horizontal scaling and how you would implement it?
Asked once · last asked Mar 3 · Concept · Mid-level
What backup plans could you use to make the IoT system safe if the Internet fails?
Asked once · last asked Mar 24 · Scenario · Mid-level
Other ways it was asked
- “What additional backup measures could make an IoT system safe if the Internet connection fails?”
How would you keep a mobile app responsive and user-friendly in low-connectivity environments?
Asked once · last asked Jun 24 · Scenario · Mid-level
How would you design observability and monitoring for a data platform, including when to implement it, how to assess current coverage, and how to identify gaps?
Asked once · last asked Jul 28 · Scenario · Senior
How would you handle a data inconsistency where System A times out but System B successfully processes the request?
Asked once · last asked Jul 31 · Scenario · Mid-level
Other ways it was asked
- “How would you design a solution to resolve the inconsistency between System A and System B when a timeout occurs but the request is still processed?”
How would you scale a monolithic system if vertical scaling reaches its limits or the client grows significantly?
Asked once · last asked Sep 24 · Design · Senior
Other ways it was asked
- “How would you scale a monolithic system horizontally?”
How do you approach scaling beyond small automations to larger, robust business systems?
Asked once · last asked Sep 29 · Design · Senior
How would you prevent duplicate survey submissions if a user taps the submit button twice?
Asked once · last asked Sep 30 · Scenario · Mid-level
Other ways it was asked
- “How would you prevent duplicate survey submissions if a student taps the submit button twice?”
What should happen when the order service receives a request while the payment service is down?
Asked once · last asked Oct 9 · Scenario · Senior
Other ways it was asked
- “How should the order service operate when the payment service is down?”
How would you handle duplicate or out-of-order callbacks using idempotency keys, and where would you enforce idempotency?
Asked once · last asked Oct 13 · Scenario · Senior
Why not replay the orders in client timestamp order?
Asked once · last asked Oct 20 · Concept · Mid-level
Other ways it was asked
- “What is the purpose of replaying orders in client timestamp order?”
How can a test prove that a request was processed exactly once?
Asked once · last asked Oct 22 · Scenario · Senior
Would firing 10,000 or 50,000 requests as separate parallel tasks work well, and how would you handle that load?
Asked once · last asked Jan 28 · Design · Senior
How would you prevent a message from being processed more than once, for example using an outbox pattern or message ID?
Asked once · last asked Jan 28 · Scenario · Senior
How would you prevent duplicate form submissions or repeated requests from being processed twice?
Asked once · last asked Jan 28 · Scenario · Mid-level
If the inventory service is down for 30 minutes while orders continue arriving, how should the system handle this without losing business or making the main service stop responding?
Asked once · last asked Jan 30 · Scenario · Senior
If a message broker such as Kafka delivers messages more than once or out of order, how should the payment service handle them to avoid deducting payment more than once?
Asked once · last asked Jan 30 · Scenario · Senior
If you were assigned a project, what measures would you take to control both cost and response time?
Asked once · last asked Feb 5 · Scenario · Mid-level
How would you use idempotency in a REST API to prevent a critical request, such as a payment, from being processed multiple times after retries or duplicate clicks?
Asked once · last asked Feb 10 · Scenario · Senior
What is a graceful shutdown?
Asked once · last asked Feb 22 · Concept · Mid-level
When you're creating a REST API, how do you ensure it efficiently handles high traffic and scales as needed?
Asked once · last asked Feb 25 · Design · Senior
How do you decide which load-balancing method best fits a specific application?
Asked once · last asked Feb 25 · Scenario · Senior
Other ways it was asked
- “When you've implemented load balancing, how do you decide which load-balancing method best fits a specific application?”
How do you build resiliency into data solutions, and what techniques do you use?
Asked once · last asked Mar 3 · Scenario · Senior
What should a retry mechanism do when an API request to retrieve transaction history fails?
Asked once · last asked Mar 5 · Concept · Mid-level
What are Layer 7 load balancers, and how do you use them?
Asked once · last asked Mar 9 · Concept · Mid-level
How would you handle a third-party vendor's API becoming unavailable in a payment-card ordering system?
Asked once · last asked Mar 16 · Scenario · Senior
How would you design a production system to withstand component failures, remain stable, and provide effective monitoring?
Asked once · last asked Mar 16 · Design · Senior
How do you handle message acknowledgments and retry logic to ensure tasks are processed reliably?
Asked once · last asked Mar 17 · Scenario · Senior
Regarding exactly-once delivery, what steps would you implement?
Asked once · last asked Mar 17 · Scenario · Senior
How would you handle tasks that take a very long time or fail unpredictably?
Asked once · last asked Mar 17 · Scenario · Senior
When using a Redis hash to detect duplicates, how long should you retain it, and when should it expire?
Asked once · last asked Mar 19 · Scenario · Mid-level
How should an order flow handle communication failures between the limit service and order service, or an unavailable order service?
Asked once · last asked Mar 19 · Scenario · Senior
If both the order service and limit service are unavailable, how should the system handle order processing, and what availability trade-offs does this create?
Asked once · last asked Mar 19 · Design · Senior
How should the order service handle a GET request to the limit service that times out or receives no response, and what should the order API communicate?
Asked once · last asked Mar 19 · Scenario · Senior
How would you ensure delivery guarantees and handle notifications that fail to reach a user's device?
Asked once · last asked Mar 19 · Scenario · Senior
How would you handle a sudden spike to hundreds of thousands of notifications per minute and automatically scale the system to meet demand?
Asked once · last asked Mar 19 · Design · Senior
If an IoT system is used for ECG monitoring and the Internet connection fails, what will happen?
Asked once · last asked Mar 24 · Scenario · Mid-level
How would you operate an IoT system in offline mode?
Asked once · last asked Mar 24 · Scenario · Mid-level
In a PHP API integrating a third-party service, how do you design retries and timeouts to avoid duplicate side effects, such as double charging, and what role does idempotency play?
Asked once · last asked Mar 26 · Design · Senior
How would you implement idempotency for a charge-customer call, including the key strategy, persistence, and response to repeated requests?
Asked once · last asked Mar 26 · Design · Senior
Other ways it was asked
- “How would you implement idempotency for a charge-customer call? What idempotency key strategy would you use, where would you persist it, and what would you return for a repeated request?”
How would you handle a failure or loss of connectivity in an edge device or another part of the processing pipeline?
Asked once · last asked Mar 27 · Scenario · Senior
How would you ensure alerts are reliably delivered to human reviewers, even if the notification service experiences downtime or message loss?
Asked once · last asked Mar 27 · Scenario · Senior
How would you address scalability issues in a software project?
Asked once · last asked Mar 27 · Scenario · Mid-level
How would you scale a land-NFT platform to support thousands of land plots?
Asked once · last asked Mar 28 · Design · Senior
How would you handle 500 users creating accounts concurrently?
Asked once · last asked Apr 9 · Scenario · Mid-level
What is the difference between a retry and a circuit breaker?
Asked once · last asked Apr 10 · Concept · Mid-level
A production microservice is receiving more traffic than it can handle. What could you do to keep it stable and prevent it from restarting?
Asked once · last asked Apr 13 · Scenario · Senior
What can you do when traffic exceeds expectations and even the running service instances cannot handle the load?
Asked once · last asked Apr 13 · Scenario · Senior
How would you handle a dependency that responds slowly or returns errors when your service calls it?
Asked once · last asked Apr 13 · Scenario · Senior
What design and planning strategies would you use to make a system highly available and suitable for 24/7 operation?
Asked once · last asked Apr 14 · Design · Senior
How would you implement idempotency end to end—including client key generation, server storage and TTL, and response replay—for a create-order API that may be retried multiple times?
Asked once · last asked Apr 17 · Design · Senior
For an object storage system like R2, what performance metrics would you measure, and how would you collect them?
Asked once · last asked Apr 22 · Design · Senior
What workload shapes or types make latency important to some object-storage customers but not others?
Asked once · last asked Apr 22 · Design · Senior
In a storage system, what reliability property might matter to a customer that isn’t captured by availability or HTTP error rates?
Asked once · last asked Apr 22 · Concept · Senior
What durability guarantees could a single-server object storage system provide?
Asked once · last asked Apr 22 · Concept · Senior
How should an object storage system respond to a drive failure, such as a drive catching fire?
Asked once · last asked Apr 22 · Scenario · Senior
If the durability target is 11 nines, how would you reason about the number of copies needed, and what factors—such as drive failure probabilities and replication timing—would you consider?
Asked once · last asked Apr 22 · Design · Senior
If an object is stored on three drives and one drive fails, what should the object storage system do?
Asked once · last asked Apr 22 · Scenario · Senior
How would you scale CyberArk to support enterprise users?
Asked once · last asked Apr 25 · Design · Senior
How would you scale a Magento store to serve more than one million users, and what areas would you focus on?
Asked once · last asked Apr 27 · Design · Senior
How would you design a highly available network for a building if money were no issue?
Asked once · last asked Apr 27 · Design · Senior
How would you implement a circuit breaker at the mobile-client level?
Asked once · last asked May 4 · Scenario · Senior
Other ways it was asked
- “Can you walk me through how you implemented a circuit breaker at the mobile-client level?”
What states and transition parameters would you use in a mobile-client circuit breaker, and why?
Asked once · last asked May 4 · Scenario · Senior
Other ways it was asked
- “What states and transition parameters did you use in the mobile-client circuit breaker, and why?”
How would you set the timing between the closed, half-open, and open states in a circuit breaker: fixed, based on exponential backoff, or adjusted according to the number of requests from a client?
Asked once · last asked May 4 · Scenario · Senior
Other ways it was asked
- “How did you set the timing between the closed, half-open, and open states in the circuit breaker: fixed, based on exponential backoff, or adjusted according to the number of requests from a client?”
During intensive AI training cycles that spike database load and background jobs, how would you design backpressure so APIs stay responsive, using queues, rate limits, circuit breakers, or load shedding?
Asked once · last asked May 5 · Design · Senior
How would you design a microservices architecture to handle heavy loads, and what technologies and mechanisms would you use?
Asked once · last asked May 5 · Design · Senior
What are the two possible CyberArk Vault redundancy configurations, and what are their pros and cons?
Asked once · last asked May 8 · Design · Senior
How would you design a web application back end that experiences occasional high-traffic spikes to handle sudden load increases without significant performance degradation?
Asked once · last asked May 8 · Design · Senior
How would you design retries for a monthly batch job?
Asked once · last asked May 11 · Concept · Senior
When scaling a segmentation or automation system from a 2-million-customer base to 41 million users, potentially affecting 10% of users, what new risks would you address first, and how would you de-risk them?
Asked once · last asked May 11 · Scenario · Senior
How would you design image uploads to perform quickly for users around the world?
Asked once · last asked May 11 · Design · Senior
How would you handle unpredictable incoming data volumes, such as 10,000 transactions one hour, a million the next, and none the following hour?
Asked once · last asked May 18 · Design · Senior
How would you design a data-processing application to scale horizontally as pods are added or removed, so performance scales with the number of pods?
Asked once · last asked May 19 · Design · Senior
How would you handle an expiring presigned URL or a failure during a large multipart upload, and ensure the upload can complete successfully?
Asked once · last asked May 21 · Scenario · Senior
How would you handle a user uploading a corrupted image in an image-processing workflow?
Asked once · last asked May 21 · Scenario · Mid-level
How should an image-processing system handle Lambda invocation failures, network issues, and exhausted retries so failed images can be recovered and processed?
Asked once · last asked May 21 · Scenario · Senior
How would you distribute one event to a very large number of users quickly and reliably without overloading a single service?
Asked once · last asked May 23 · Design · Senior
How would you design a notification system to handle a regional outage while maintaining delivery guarantees?
Asked once · last asked May 23 · Design · Senior
How would you keep client connections and subscriptions working when traffic fails over to another region?
Asked once · last asked May 23 · Design · Senior
How would you design observability across regions so you can trace a single notification from publishing through fan-out to delivery confirmation?
Asked once · last asked May 23 · Design · Senior
How would you design a fallback path if the real-time channel is unavailable while keeping the user experience acceptable?
Asked once · last asked May 23 · Design · Senior
How would you prevent duplicate user-visible notifications when a real-time notification path recovers after fallback delivery?
Asked once · last asked May 23 · Design · Senior
How would you design an application to handle one million users per second?
Asked once · last asked May 25 · Design · Senior
How would you handle a situation where money is deducted by the payment gateway but your application does not receive the payment update?
Asked once · last asked May 25 · Scenario · Senior
In a production Node.js service, how do you decide between using cluster and running multiple single-threaded processes, for example with PM2 or Kubernetes, and what are the key failure and observability tradeoffs?
Asked once · last asked May 29 · Design · Senior
How do you implement idempotency for a Lambda that can be retried, including timeouts or partial failures while writing to DynamoDB and publishing an event? What's your approach to avoiding duplicates end to end?
Asked once · last asked May 29 · Scenario · Senior
In PostgreSQL, how would you design an idempotency mechanism to process each event exactly once while still allowing safe retries?
Asked once · last asked May 29 · Design · Senior
How would you identify and handle failure points when scaling a document-processing pipeline from 50 documents to hundreds of thousands or millions?
Asked once · last asked Jun 12 · Scenario · Senior
What architectural pattern would you use to handle errors in a Kafka-based system?
Asked once · last asked Jun 15 · Scenario · Senior
How can an event-driven architecture help address race conditions in order processing?
Asked once · last asked Jun 18 · Concept · Senior
How would you improve an application's reliability and reduce latency?
Asked once · last asked Jun 18 · Scenario · Senior
How would you address a scalability problem in a microservices system?
Asked once · last asked Jun 19 · Design · Senior
How would you design a robust error-handling strategy?
Asked once · last asked Jun 24 · Scenario · Senior
How can a Kafka consumer prevent the same event from being processed more than once?
Asked once · last asked Jun 25 · Scenario · Senior
How can a consumer use an event's unique identifier to prevent duplicate processing?
Asked once · last asked Jun 25 · Scenario · Mid-level
After fixing a processing failure, how should you decide whether a failed event is still valid to replay?
Asked once · last asked Jun 25 · Scenario · Senior
If event processing order matters, under what conditions can a delayed event be processed a week later?
Asked once · last asked Jun 25 · Scenario · Senior
If a downstream service becomes slow, times out, or returns 503 errors, what can the calling service do to avoid overloading it and give it time to recover?
Asked once · last asked Jun 25 · Scenario · Senior
What is your approach and mindset when dealing with low-latency requirements, and how do you migrate features while working with a live system?
Asked once · last asked Jun 26 · Scenario · Senior
How would you design the architecture for a new product so it can scale as its usage grows?
Asked once · last asked Jun 26 · Design · Senior
How would you choose and validate an idempotency key for updates in PostgreSQL?
Asked once · last asked Jun 29 · Scenario · Mid-level
Could you explain the difference between horizontal and vertical scaling in the context of back-end systems?
Asked once · last asked Jul 1 · Concept · Junior
How would you tune retry behavior and the backoff strategy for an asynchronous pipeline?
Asked once · last asked Jul 5 · Scenario · Senior
What practices do you use when calling an external API to make the integration resilient and reliable?
Asked once · last asked Jul 16 · Scenario · Mid-level
When building a high-availability solution, what components would you consider?
Asked once · last asked Nov 18 · Design · Senior
What happens if a downstream activation is failing, and how do you prevent double activation?
Asked once · last asked Jul 16 · Scenario · Senior
How would you control application costs as the number of users grows?
Asked once · last asked Jul 22 · Scenario · Mid-level
In a distributed system with microservices, how do you prevent duplicate processing?
Asked once · last asked Jul 22 · Concept · Senior
How do you prevent duplicate requests from being processed more than once in a booking or trading workflow?
Asked once · last asked Jul 22 · Scenario · Senior
Imagine your system starts seeing a sudden spike in traffic—10 times more than usual. What are your first steps to ensure the system stays stable and responsive?
Asked once · last asked Jul 22 · Scenario · Senior
Imagine you have a microservice that processes events asynchronously and need to ensure each event is handled exactly once, with no duplicates. How would you approach that design?
Asked once · last asked Jul 22 · Design · Senior
How do you ensure there are enough workers to take things off the queue?
Asked once · last asked Jul 24 · Scenario · Senior
Which failures should prevent an application from sending an SMS through Twilio?
Asked once · last asked Jul 26 · Scenario · Mid-level
Can two identical concurrent requests still cause duplicate messages in an otherwise secure SMS implementation?
Asked once · last asked Jul 26 · Scenario · Senior
A messaging provider accepts an SMS, but the network times out before your worker receives the response. What should the system do, and why?
Asked once · last asked Jul 26 · Scenario · Senior
Why might automatically retrying an SMS request after a timeout cause problems?
Asked once · last asked Jul 26 · Concept · Senior
Two nearly simultaneous webhook requests sent duplicate SMS messages for the same call. Where is the weakness, and how would you fix it?
Asked once · last asked Jul 26 · Scenario · Senior
How do you decide whether a service should be stateless or stateful?
Asked once · last asked Jul 27 · Design · Senior
In a workflow spanning multiple microservices, how do you avoid duplication, handle retries, and recover if something fails?
Asked once · last asked Jul 27 · Design · Senior
How do you manage service dependencies so the code only runs when required dependencies are available?
Asked once · last asked Jul 27 · Scenario · Senior
How do you prevent double deduction when the same payment request is retried?
Asked once · last asked Jul 27 · Scenario · Senior
How should an application handle a weather API outage?
Asked once · last asked Jul 27 · Scenario · Mid-level
How do you encourage a team to consider system performance, workload volume, and scalability?
Asked once · last asked Jul 27 · Scenario · Senior
How would you optimize the architecture of a three-tier monolith for performance during the MVP phase of an ecommerce startup?
Asked once · last asked Jul 27 · Design · Senior
How would you make sure the systems scale properly and stay stable as the product grows fast?
Asked once · last asked Jul 28 · Design · Senior
Would a WebSocket-based approach scale to hundreds of millions of users?
Asked once · last asked Jul 28 · Design · Senior
How would you evaluate whether a chat system design can handle the expected user load?
Asked once · last asked Jul 28 · Design · Senior
How would you configure CyberArk CPM instances behind a load balancer: active-active or active-standby, and why?
Asked once · last asked Jul 31 · Design · Senior
How do you approach error handling and ensure reliability in your systems?
Asked once · last asked Jul 31 · Scenario · Senior
In a banking application, a user submits a payment, the request times out without a response, and the user submits the same payment again. How would you prevent it from being processed twice?
Asked once · last asked Jul 31 · Scenario · Senior
Design a high-level architecture for an application that can process 5,000 transactions per second. Which components would you include, which operations would be synchronous or asynchronous, and how would you ensure availability and scalability?
Asked once · last asked Jul 31 · Design · Senior
How would you configure BullMQ retries and backoff for a 24/7 Zoom recording pipeline encountering API rate limits, and what does fail-safe deletion mean in that architecture?
Asked once · last asked Aug 2 · Tooling · Senior
How would you handle 100 concurrent requests in your system?
Asked once · last asked Aug 2 · Scenario · Mid-level
How do you assess whether an automation workflow can serve multiple teams, and what challenges arise when maintaining or scaling it?
Asked once · last asked Aug 4 · Scenario · Senior
How would you handle a significant increase in concurrent users during peak times while preventing seat double booking?
Asked once · last asked Aug 5 · Scenario · Senior
How would you implement reliable audit logging, error alerting, and real-time monitoring for an event ticket booking system, and which tools or practices would you use?
Asked once · last asked Aug 5 · Design · Senior
Other ways it was asked
- “How would you ensure reliable auditing, error alerting, real-time monitoring, and audit logging for an event ticket booking system?”
What failure modes do you anticipate in an event ticket booking system, and how would you mitigate them to ensure graceful degradation?
Asked once · last asked Aug 5 · Scenario · Senior
How would you design the system to handle 12,000 tickets per week from day one?
Asked once · last asked Aug 7 · Design · Senior
How would you architect a system for bursty asynchronous requests, keeping workers private while autoscaling them to handle demand?
Asked once · last asked Aug 10 · Design · Senior
How would you implement idempotency end to end so duplicates are prevented even if the API times out and the client retries while a worker is mid-processing?
Asked once · last asked Aug 10 · Scenario · Senior
How would you prevent duplicate processing and ensure correct ordering when consumers receive the same event multiple times or out of order?
Asked once · last asked Aug 11 · Design · Senior
What steps and tools would you use to set up a cluster and validate failover?
Asked once · last asked Aug 11 · Scenario · Senior
Design an improved architecture for the label purchase and upload flow that keeps the current behavior but addresses the latency and failure issues when object storage is inaccessible.
Asked once · last asked Aug 11 · Design · Senior
Other ways it was asked
- “Design an improved architecture for the label purchase flow that preserves synchronous behavior for clients needing immediate label availability while adding optional asynchronous uploads for clients that do not.”
Where would you implement idempotency in a label purchase and delivery system?
Asked once · last asked Aug 11 · Design · Senior
How would you make concurrent compilation pipelines safe and scalable?
Asked once · last asked Aug 12 · Design · Senior
If you’re handling an API with large traffic, how do you keep it from crashing?
Asked once · last asked Aug 14 · Scenario · Mid-level
If a third-party PII-redaction dependency fails and normalized events can no longer be generated, how should the system respond and recover?
Asked once · last asked Aug 14 · Scenario · Senior
How will your design handle significant growth or sudden load spikes?
Asked once · last asked Aug 17 · Design · Mid-level
What are the primary failure modes of your system, and how would it degrade gracefully if a dependency fails?
Asked once · last asked Aug 17 · Design · Senior
What metrics would you track to measure the system's performance and ensure it is working as intended?
Asked once · last asked Aug 17 · Design · Mid-level
What failure modes can prevent a job-processing system from processing each job exactly once under concurrent execution?
Asked once · last asked Aug 18 · Scenario · Mid-level
How would you architect a low-latency environment with very high availability requirements?
Asked once · last asked Aug 18 · Design · Senior
If a system's request load grew from 100,000 requests to 10 times that level, where would bottlenecks arise, and how would you address them?
Asked once · last asked Aug 19 · Scenario · Senior
How would you implement idempotency in an application?
Asked once · last asked Aug 20 · Design · Senior
How do you handle events, and what do you do when a consumer fails?
Asked once · last asked Aug 20 · Scenario · Senior
How would you handle retrying a failed event?
Asked once · last asked Aug 20 · Scenario · Mid-level
What methodology would you use to make GPU clusters highly available?
Asked once · last asked Aug 20 · Design · Senior
Other ways it was asked
- “For high availability, what methodology would you use to make these GPU clusters highly available?”
For a physical GPU cluster, how would you choose a high-availability backup topology, such as one-to-one versus one-to-three, and why?
Asked once · last asked Aug 20 · Design · Senior
In Python, how would you structure an idempotent external side-effecting step—for example, charging a card and writing to a database—to guarantee exactly-once behavior under retries and worker crashes?
Asked once · last asked Aug 24 · Design · Senior
When designing a Python services API client layer that calls multiple third-party APIs, how do you structure timeouts, retries, circuit breakers, and observability so failures do not cascade?
Asked once · last asked Aug 24 · Design · Senior
If a facility goes down during an inventory reservation, how should the system behave on retry?
Asked once · last asked Aug 24 · Scenario · Senior
How would you make rate-limit enforcement idempotent?
Asked once · last asked Aug 24 · Design · Senior
How would you process and display 100,000 records at once within a few seconds after a user clicks to view them?
Asked once · last asked Aug 25 · Design · Senior
Other ways it was asked
- “How would you process and display 100,000 records within a few seconds after a user clicks to view them?”
How would you handle 20,000 concurrent users in a game?
Asked once · last asked Aug 26 · Design · Senior
How would you horizontally scale real-time game servers without disconnecting existing users?
Asked once · last asked Aug 26 · Design · Senior
How do we mitigate or prevent data loss and orphaned records if Redis crashes and Sidekiq loses the job queue?
Asked once · last asked Aug 26 · Scenario · Senior
How would you handle jobs that hang or fail when a worker machine crashes?
Asked once · last asked Aug 26 · Scenario · Senior
In your mind, what are the key failure points for remote access architectures, and how do you design around them for the highest availability?
Asked once · last asked Aug 27 · Design · Senior
Other ways it was asked
- “What other single points of failure can affect remote access architectures?”
How do you architect highly available etcd clusters across multiple on-premises server racks or server rooms?
Asked once · last asked Aug 30 · Design · Senior
How would you ensure reliable message delivery and handle traffic spikes in an Azure Service Bus consumer?
Asked once · last asked Sep 1 · Design · Senior
What data replication and traffic failover architecture would you propose to achieve an RTO under 15 minutes and an RPO under 1 minute if a cloud provider fails, and how would you test the disaster recovery plan?
Asked once · last asked Sep 1 · Design · Senior
How would you design for reliability in a data system that people use to make decisions?
Asked once · last asked Sep 2 · Design · Senior
How would you design idempotency for create-order POST requests and retries or refreshes, so flaky network connections don't create duplicate rows in PostgreSQL?
Asked once · last asked Sep 3 · Design · Senior
How would you handle a growing queue backlog when usage increases?
Asked once · last asked Sep 3 · Scenario · Senior
How would you implement retries for a failed background job: requeue the message or retry within the same worker?
Asked once · last asked Sep 3 · Design · Mid-level
When building software or designing a system composed of multiple pieces of software, what does reliability mean to you? How would you build a reliable system?
Asked once · last asked Sep 3 · Design · Senior
What does dividing by 86,400 seconds calculate when estimating QPS?
Asked once · last asked Sep 4 · Concept · Mid-level
What approaches would you use to make a backend system scalable?
Asked once · last asked Sep 4 · Scenario · Senior
If a notification service is unavailable, how can an architecture ensure queued notifications are delivered when it recovers, and where should that logic reside?
Asked once · last asked Sep 4 · Scenario · Senior
How can a load balancer be configured to handle both read and write traffic?
Asked once · last asked Sep 4 · Concept · Mid-level
What factors can cause a HashiCorp Consul deployment for storing environment variables to fail?
Asked once · last asked Sep 4 · Scenario · Senior
How do you handle idempotency, failed transactions, duplicate requests, and database consistency in a payment flow?
Asked once · last asked Sep 4 · Scenario · Senior
How do you handle a scheduler running on a multi-instance application?
Asked once · last asked Sep 4 · Scenario · Senior
Redis goes down briefly—what are your failure mode options, and how do you keep the system safe?
Asked once · last asked Sep 6 · Scenario · Senior
An invoicing service needs to handle 10 times its current traffic. What would you investigate first?
Asked once · last asked Sep 6 · Design · Senior
During peak holiday shopping, an IVR's order-status Lambda function querying DynamoDB hits its concurrency limit and times out amid a call spike. How would you change the architecture or AWS configuration to handle the bottleneck, prevent dropped calls, and manage the customer experience during delays?
Asked once · last asked Sep 6 · Design · Senior
Other ways it was asked
- “During peak holiday shopping hours, an IVR experiences a massive spike in concurrent calls, causing the AWS Lambda function that looks up order statuses in Amazon DynamoDB to hit its concurrency limit and time out. How would you modify the system design or AWS configuration to handle the bottleneck, ensure a smooth customer experience without dropping calls, and handle the customer experience during the delay?”
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How this list is made
Every question here was asked by a real interviewer in a real job interview that a candidate ran MeetAssist in. After the call, the interviewer's questions are pulled from the transcript. Practice sessions, tests, exams and anything that was not a job interview are dropped.
Questions are rewritten so they make sense on their own: names of people, employers and clients are removed, and speech-to-text mistakes are fixed. Small talk, logistics and questions about one candidate's own résumé are left out. Rephrasings of the same question are merged, and the count is the number of different interviews it came up in.
The interviews come from candidates who use MeetAssist, so they lean towards software, data and AI roles: the shares describe these interviews, not every System Design interview. Answers to the most asked questions are written and checked by an editor; a "common mistake" is shown only when reviews of real answers in these interviews show it, with the count.
942 interviews, 495 candidates, Oct 2025 to Oct 2026. Updated every month with new interviews.
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