Top 4 Retries Interview Questions
Browse 4 real-world technical and behavioral interview questions about Retries. Review scenarios, edge cases, and architectural best practices.
A dependency that normally answers in 80ms starts taking eight seconds. What in your service reacts, and in what order?
A timeout shorter than the caller's patience is the only defence that works without cooperation. Retries need idempotency, jitter and a budget or they amplify the outage; a breaker must trip on latency as well as errors; and a bulkhead is what stops one slow dependency consuming every thread.
A client times out and retries your POST /payments call. How do you make that endpoint idempotent?
Take an idempotency key from the client and store it in a uniquely-constrained row written in the same transaction as the effect, so the dedupe record and the work commit together. Replay the stored response on a repeat, refuse a retry arriving mid-flight, and expire keys past the retry horizon.
A payment API times out and the client retries. How do you guarantee the customer is not charged twice?
Prevent a double charge on payment retry with an idempotency key tied to the purchase intent, a unique constraint, atomic charge recording, honest in-flight retry responses and settlement reconciliation.
The client retries a charge because your response timed out. The money must move once. What makes that true?
An idempotency key for retried charges is minted by the client per payment intent, claimed under a unique constraint in the same transaction as the charge, and used to replay the stored response on repeat. The API contract must define retention, in-flight retries and mismatched request bodies.