Centralized vs distributed auth in Microservices - Practice Questions

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Centralized Authentication

In a microservices system using centralized authentication, what is the main role of the authentication server?

A It issues tokens and validates user credentials for all services.

B Each microservice independently verifies user credentials.

C It stores user data but does not handle token issuance.

D It only logs authentication attempts without validating users.

💡 Hint

Think about where the user login happens and who trusts the tokens.

In centralized authentication, a dedicated server handles login and issues tokens. Microservices trust these tokens instead of verifying credentials themselves.

❓ Architecture

intermediate

Distributed Authentication Token Validation

In a distributed authentication system, how do microservices typically validate user tokens without a central server?

A Tokens are not validated; services trust all requests.

B Services send token validation requests to a central database.

C Services require users to re-login for each service.

D Each service uses a shared secret or public key to verify token signatures locally.

💡 Hint

Think about how services can trust tokens without asking a central server every time.

Distributed systems often use signed tokens (like JWT) that services can verify locally using a shared secret or public key, avoiding central validation calls.

❓ scaling

advanced

Scaling Challenges of Centralized Authentication

What is a major scaling challenge when using centralized authentication in a large microservices environment?

A The authentication server can become a bottleneck and single point of failure.

B Microservices cannot share user data easily.

C Users must authenticate separately for each microservice.

D Tokens cannot be revoked once issued.

💡 Hint

Consider what happens if many services rely on one server for login.

Centralized authentication means all login requests go to one server, which can slow down or fail under heavy load, affecting the whole system.

❓ tradeoff

advanced

Tradeoffs Between Centralized and Distributed Auth

Which tradeoff best describes the difference between centralized and distributed authentication in microservices?

A Centralized auth requires no tokens; distributed auth requires tokens for every request.

B Centralized auth simplifies token management but risks bottlenecks; distributed auth improves scalability but adds complexity.

C Centralized auth is always faster; distributed auth is always slower.

D Centralized auth cannot support multiple user types; distributed auth can.

💡 Hint

Think about simplicity versus scalability and complexity.

Centralized auth is easier to manage but can slow down under load. Distributed auth scales better but needs more complex token verification and key management.

❓ estimation

expert

Estimating Token Validation Load in Distributed Auth

A microservices system has 100 services and 10,000 users making 1 request per second each. If each service validates tokens locally, approximately how many token validations happen per second across the system?

A 100,000 validations per second

B 10,000 validations per second

C 1,000,000 validations per second

D 100 validations per second

💡 Hint

Multiply users, requests per second, and number of services involved per request.

Each user makes 1 request per second. If each request touches all 100 services and each service validates the token, total validations = 10,000 users * 1 req/sec * 100 services = 1,000,000 validations/sec.