Q101. How does a CDN improve performance and how would you design for it?
A content delivery network caches content on edge servers close to users, reducing latency and offloading the origin. How it works: DNS or anycast routes the user to a ne...
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Job Interview Questions and Answers Directory
Search and filter frequently asked interview questions across technical, programming, and behavioral domains. Tailor your interview preparation by difficulty for freshers or experienced developers (182 available).
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Q102. How would you design a thread pool?
A thread pool keeps a set of worker threads alive so tasks avoid per-request thread-creation cost. Core pieces: - A task queue, typically bounded, holding runnable work. ...
Q103. How would you refactor a god class into a maintainable design?
A god class is large, does many unrelated things, has many dependencies and is touched by most changes. Treat the refactor as a series of safe, behaviour-preserving steps...
Q104. What is Simpson paradox?
Simpson's paradox is when a trend appears in several groups but reverses or disappears when the groups are combined. It happens because a confounding variable is unevenly...
Q105. How would you design a change data capture pipeline?
CDC captures row-level changes from a source database and streams them downstream with low latency. A typical design: - Capture: read the database transaction log with a ...
Q106. How would you design a multi-level caching architecture?
Layer caches by distance from the caller and accept that each layer adds staleness and invalidation complexity. Typical design: - Edge/CDN: cache public and static respon...
Q107. How would you design machine-to-machine authentication?
For service-to-service calls, avoid shared static credentials and long-lived secrets. - OAuth 2.0 client credentials: each service is a registered client with a client id...
Q108. What is the transactional outbox pattern and why is it needed?
A service often must both change its database and publish an event. Writing to the database and then to the broker is a dual write: a crash between the two loses the even...
Q109. How do you handle a distributed transaction without two-phase commit?
Two-phase commit is rarely used in microservices because it needs a coordinating transaction manager, holds locks across services, blocks on coordinator failure and hurts...
Q110. How do you model a long-running operation in REST?
Do not hold the connection open. Instead accept the work and return 202 Accepted with a pointer to a status resource. ```http POST /reports Location: /reports/jobs/789 Re...