Question 1

How do you apply Clean Architecture and separation of concerns in a Node.js application?

Accepted Answer

Divide the system into concentric layers: Entities, Use Cases, Controllers/Presenters, and Infrastructure, with dependencies always pointing inward toward abstract business logic.

Question 2

How do Message Queues such as BullMQ help process complex background tasks?

Accepted Answer

They separate request handling from heavy processing: the request is quickly recorded in a Redis queue, the user gets an immediate response, and worker servers process the task in the background.

Question 3

How do Consumer Groups work in Apache Kafka with Node.js servers?

Accepted Answer

They distribute reads from Topic Partitions among multiple parallel Node.js application instances for fast horizontal processing while preserving order.

Question 4

Compare gRPC and REST for communication between Node.js microservices (Microservices).

Accepted Answer

gRPC uses HTTP/2 and fast, compact, strongly typed binary Protocol Buffers, making it faster and lighter on the network than REST/JSON.

Question 5

What is the Circuit Breaker pattern, and how does it prevent Cascading Failures?

Accepted Answer

It monitors failures when connecting to external services; if errors exceed a threshold, it opens the circuit and fails requests immediately without sending them, preserving server resources.

Question 6

How do you implement Distributed Tracing in Node.js with the OpenTelemetry standard?

Accepted Answer

Generate a shared Trace ID and propagate it through request headers (W3C Trace Context) to link a request's path and logs across participating servers and databases.

Question 7

Why prefer Structured JSON Logging with libraries such as Pino over console.log?

Accepted Answer

Pino outputs structured JSON objects with clear severity levels and timestamps, and logs very quickly without blocking.

Question 8

What is the key difference between Liveness Probe and Readiness Probe in Kubernetes for Node.js applications?

Accepted Answer

Liveness checks whether the process is alive and not frozen (otherwise it is restarted), while Readiness checks whether the application is ready to receive requests (for example, whether its database connection is ready).

Question 9

What are the security and performance best practices for building Docker containers for Node.js applications?

Accepted Answer

Use Multi-Stage Builds to reduce image size, run as a non-root user, and use dumb-init as PID 1 to handle system signals gracefully.

Question 10

How do you design Idempotent Consumers in distributed Node.js systems?

Accepted Answer

Store the unique event ID (Event ID) in a database column with a unique constraint inside an atomic transaction, ensuring repeated processing produces the same result without duplicate effects.