API gateway patterns in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

What is the primary role of an API Gateway in 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 directly manages the internal communication between microservices without client involvement.

C It replaces the need for load balancers by distributing traffic evenly.

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

💡 Hint

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

An API Gateway provides a unified entry point for clients, routing requests to appropriate backend services. It does not store data or replace load balancers but complements them.

❓ Architecture

intermediate

Which API Gateway pattern best supports aggregating data from multiple microservices into one response?

Select the API Gateway pattern designed to combine responses from several services into a single client response.

A Aggregator Pattern

B Proxy Pattern

C Chained Pattern

D Facade Pattern

💡 Hint

Think about a pattern that collects and merges data from different sources.

The Aggregator Pattern collects data from multiple backend services and combines it into one response for the client, simplifying client interactions.

❓ scaling

advanced

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

Identify the way an API Gateway contributes to system scalability.

A By storing user sessions and state information centrally.

B By caching responses and reducing repeated calls to backend services.

C By directly scaling database clusters automatically.

D By replacing microservices with a monolithic service.

💡 Hint

Consider how reducing backend load can help scale the system.

API Gateways can cache frequent responses, which reduces the number of calls to backend services, thus improving scalability and performance.

❓ tradeoff

advanced

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

Choose the main disadvantage or risk introduced by adding an API Gateway.

A It always increases the overall system latency significantly.

B It eliminates the need for security measures in backend services.

C It removes the need for service discovery mechanisms.

D It can become a single point of failure if not designed with redundancy.

💡 Hint

Think about what happens if the gateway stops working.

An API Gateway centralizes traffic, so if it fails and lacks redundancy, it can bring down access to all services, making it a critical point to protect.

❓ estimation

expert

Estimate the number of concurrent connections an API Gateway must handle for a system with 10,000 daily active users, each making 50 requests per hour during peak 2 hours.

Calculate the approximate concurrent connections the API Gateway should support during peak load.

A Approximately 140,000 concurrent connections

B Approximately 14,000 concurrent connections

C Approximately 7,000 concurrent connections

D Approximately 700 concurrent connections

💡 Hint

Calculate total requests during peak, then estimate how many happen simultaneously assuming average request duration.

10,000 users × 50 requests/hour = 500,000 requests/hour. Peak is 2 hours, so 500,000 requests spread over 2 hours = 250,000 requests/hour during peak. That is about 69 requests per second (250,000 / 3600). Assuming each request lasts 100ms (0.1s), concurrent connections = 69 × 0.1 = ~7. So 700 is a safe estimate considering bursts and overhead.