Interview Q&A

uthorization using an API Gateway?

Rate Limiting:

• Use the API Gateway to limit the number of requests a client can make in a given

period to prevent abuse and overload. This can be done using libraries or built-in

functionality in the gateway (e.g., NGINX, Kong).

• Example: Limit each client to 100 requests per minute.

uthentication:

• The API Gateway can integrate with external identity providers (e.g., OAuth 2.0,

JWT) to authenticate requests. It verifies the client's identity before forwarding

requests to the microservices.

• Example: If a request includes a valid JWT token, the gateway passes it

long; otherwise, it responds with an authentication error.

uthorization:

• The API Gateway can handle Role-Based Access Control (RBAC) by verifying

user roles from the authentication token (JWT) and enforcing access restrictions

based on the user's privileges.

• Example: Only admins can access /admin endpoints, while regular users

can access /user endpoints.

Rate Limiting:

• Use the API Gateway to limit the number of requests a client can make in a given

period to prevent abuse and overload. This can be done using libraries or built-in

functionality in the gateway (e.g., NGINX, Kong).

• Example: Limit each client to 100 requests per minute.

Authentication:

• The API Gateway can integrate with external identity providers (e.g., OAuth 2.0,

JWT) to authenticate requests. It verifies the client's identity before forwarding

requests to the microservices.

• Example: If a request includes a valid JWT token, the gateway passes it

along; otherwise, it responds with an authentication error.

Authorization:

• The API Gateway can handle Role-Based Access Control (RBAC) by verifying

user roles from the authentication token (JWT) and enforcing access restrictions

based on the user's privileges.

• Example: Only admins can access /admin endpoints, while regular users

can access /user endpoints.

PI Gateway?

Routing:

• The API Gateway routes incoming requests to the appropriate microservice based on

the URL, method, or other attributes. It can also aggregate responses from multiple

services and return a unified response.

• Example: Requests to /user are routed to the User Service, and /order to

the Order Service.

Load Balancing:

• The API Gateway often integrates with a load balancer to distribute requests across

multiple instances of a service, ensuring better resource utilization and failover

support.

• Example: Requests to a microservice like User Service can be distributed

mong several instances based on a round-robin or least-connections

strategy.

Caching:

• API Gateways can cache responses for repeated requests, reducing the load on

backend services and improving response times for frequently accessed data.

• Example: Cache responses to user profiles for 1 minute to avoid querying the

User Service on every request.

Follow :

Routing:

• The API Gateway routes incoming requests to the appropriate microservice based on

the URL, method, or other attributes. It can also aggregate responses from multiple

services and return a unified response.

• Example: Requests to /user are routed to the User Service, and /order to

the Order Service.

Load Balancing:

• The API Gateway often integrates with a load balancer to distribute requests across

multiple instances of a service, ensuring better resource utilization and failover

support.

• Example: Requests to a microservice like User Service can be distributed

among several instances based on a round-robin or least-connections

strategy.

Caching:

• API Gateways can cache responses for repeated requests, reducing the load on

backend services and improving response times for frequently accessed data.

• Example: Cache responses to user profiles for 1 minute to avoid querying the

User Service on every request.

Answer: PI versioning allows clients to continue using older versions of an API while enabling the introduction of new features. Implementation:

What interviewers expect

• A clear definition tied to Microservices in Microservices projects
• Trade-offs (performance, maintainability, security, cost)
• When you would and would not use it in production

Real-world example

In a production Microservices application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.

How to explain in the interview

1. Define the concept in one or two sentences.
2. Context — where it fits in Microservices architecture.
3. Example — a specific project, bug, or performance win.
4. Trade-off — what you gain vs what you sacrifice.

Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.

like logging, monitoring, and security?

What interviewers expect

• A clear definition tied to Microservices in Microservices projects
• Trade-offs (performance, maintainability, security, cost)
• When you would and would not use it in production

Real-world example

In a production Microservices application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.

How to explain in the interview

1. Define the concept in one or two sentences.
2. Context — where it fits in Microservices architecture.
3. Example — a specific project, bug, or performance win.
4. Trade-off — what you gain vs what you sacrifice.

Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.