API gateway concept in Express - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

What is the primary role of an API Gateway in a microservices architecture?

Choose the best description of the main function of an API Gateway.

A It acts as a single entry point that routes client requests to multiple backend services.

B It stores all the data for the microservices in a centralized database.

C It replaces the need for backend services by handling all business logic itself.

D It directly connects clients to each microservice without any routing.

💡 Hint

Think about how clients interact with many services through one interface.

An API Gateway acts as a single entry point that routes requests to the correct backend services, simplifying client communication.

❓ Architecture

intermediate

Which component is NOT typically handled by an API Gateway?

Select the feature that an API Gateway usually does NOT provide.

A Request routing and load balancing

B Authentication and authorization

C Direct database query execution

D Response aggregation from multiple services

💡 Hint

Consider what tasks are usually done by backend services versus the gateway.

API Gateways route requests and handle security but do not execute database queries directly; that is done by backend services.

❓ scaling

advanced

How does an API Gateway help improve scalability in a distributed system?

Choose the option that best explains how an API Gateway supports system scalability.

A By storing all user sessions centrally in the gateway

B By directly managing database connections for all services

C By replacing backend services with a single monolithic service

D By caching responses and reducing load on backend services

💡 Hint

Think about how reducing repeated work can help scale better.

API Gateways can cache frequent responses, reducing backend load and improving scalability.

❓ tradeoff

advanced

What is a common tradeoff when using an API Gateway in system design?

Identify the main downside of introducing an API Gateway.

A It can become a single point of failure if not designed for high availability.

B It eliminates the need for backend services, increasing complexity.

C It requires clients to connect directly to multiple services.

D It reduces security by exposing all backend services publicly.

💡 Hint

Consider what happens if the gateway goes down.

The API Gateway centralizes traffic, so if it fails, the whole system can become unreachable unless it is highly available.

❓ component

expert

In an Express-based API Gateway, which middleware is best suited to handle authentication before routing requests?

Select the middleware type that should be used to authenticate requests in an Express API Gateway.

A A middleware that modifies response headers after sending the response

B A global middleware that checks tokens before any route handlers

C A route-specific middleware that runs after forwarding the request

D A middleware that only logs requests without blocking unauthorized ones

💡 Hint

Authentication should happen early to block unauthorized access.

Global middleware runs before routing and can block unauthorized requests early, improving security.