Interview Q&A

Short answer: In Kubernetes, load balancing is an integral part of service discovery and can be implemented in the following ways:

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Client-Side Load Balancing: In client-side load balancing, the client is responsible for selecting the appropriate instance of a service to send the request to, based on the list of available instances.

Explain a bit more

The client usually obtains the list of service instances through service discovery (e.g., Consul, Eureka, Kubernetes DNS). Pros: More control for the client on load balancing strategies (e.g., round-robin, least connections). Reduces pressure on centralized load balancers. Cons: Adds complexity to client-side logic. Requires the client to maintain a list of available instances. Server-Side Load Balancing: In server-side load balancing, a centralized load balancer (e.g., NGINX, HAProxy, Kubernetes ingress controller) is responsible for distributing the traffic to available service instances. Pros: Simpler client-side logic. Centralized control over load balancing logic and configuration. Cons: Can introduce a bottleneck or single point of failure. Requires more resources and maintenance for the load balancer itself.

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1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: DNS-based Service Discovery is a method where DNS (Domain Name System) is used to resolve the network location (IP address) of a service instance in a microservices architecture. How it works:

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: And how do you overcome them? Challenges:

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: In Kubernetes, service discovery is managed through the Kubernetes DNS system.

Explain a bit more

Each service is given a DNS name that resolves to its pods (or group of pods), allowing services to find and communicate with each other. Kubernetes Services: A Kubernetes Service is an abstraction layer over a set of Pods. Services provide a stable IP address and DNS name, even though the Pods may be dynamically created or destroyed. For example, a service named order-service in the default namespace would be reachable as order-service.default.svc.cluster.local. Kubernetes DNS: Kubernetes automatically configures DNS for services in a cluster, so services can resolve the name of another service (e.g., order-service) to the appropriate IP address. Service Types: Kubernetes supports different service types like ClusterIP, NodePort, and LoadBalancer, each serving different use cases for internal or external service discovery.

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1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: rchitecture? service registry is a centralized directory of available services and their instances. It helps microservices locate and communicate with each other. How it works: Each microservice registers itself with the service registry when it starts, providing metadata like its IP address, port, and health status. Other microservices query… the… registry…… to discover and connect to the required service. Service…

Explain a bit more

registries also support health checks, ensuring that only healthy services re discoverable. Tools: Examples of service registries include Consul, Eureka, and Zookeeper.

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: A Service Registry is a database or directory that stores information about services, their instances, and their locations (IPs and ports). It acts as a directory for services to register and clients to look up services.

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Sticky Sessions (Session Affinity) ensure that a user’s requests are always routed to the same service instance throughout the duration of a session. How to implement:

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: For multi-region or multi-cloud environments, service discovery must handle the complexity of services spread across different geographic locations or cloud providers.

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: To secure communication between microservices, you can implement a combination of encryption, authentication, and authorization strategies:

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: uthenticate each other using TLS certificates. How it works: Server Authentication: The client verifies that it is communicating with the legitimate server by checking the server's certificate. Client Authentication: The server also verifies that the client is legitimate by checking the client's certificate. Importance in Microservices:

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Mutual TLS (mTLS) is an authentication protocol where both the client and server authenticate each other using TLS certificates. How it works: Server Authentication: The client verifies that it is communicating with the legitimate server by checking the server's certificate. Client Authentication: The server also verifies that the client is legitimate by checking the client's certificate. Importance in Microservices:

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: user's data without exposing credentials.

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: OAuth 2.0 is an open standard for authorization that enables third-party services to access a user's data without exposing credentials.

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: An API Gateway serves as a reverse proxy that routes requests from clients to backend microservices, providing an essential layer of security.

Real-world example (ShopNest)

ShopNest’s API Gateway routes /orders to the Order service and /payments to Payment—clients talk to one entry point.

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1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Role-Based Access Control (RBAC) assigns permissions based on the roles that users or services have within an application.

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: passwords, tokens) in microservices?

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Cross-Site Request Forgery (CSRF) is an attack where an attacker tricks the user into making a request to a service they are authenticated to, potentially causing unintended actions.

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: uthorized, and encrypted. Key Principles:

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: The Zero Trust Security model assumes that both internal and external networks are untrusted, and therefore, every request (internal or external) must be authenticated, authorized, and encrypted. Key Principles:

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: (Distributed Denial of Service) attacks?

Real-world example (ShopNest)

If Payment is down, the Order service fails fast with a circuit breaker instead of hanging every checkout thread.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: How do you ensure that microservices are resilient to DDoS (Distributed Denial of Service) attacks? is a common interview topic in Microservices. Give a clear definition, then one concrete example.

Real-world example (ShopNest)

If Payment is down, the Order service fails fast with a circuit breaker instead of hanging every checkout thread.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: The Bulkhead pattern is a resilience design pattern that isolates failures to prevent them from spreading and affecting other parts of the system. The idea is to create compartments or isolated pools within the system, so that failure in one compartment doesn’t bring down the entire service. Implementation:

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: The Retry pattern involves retrying an operation that has failed due to transient issues, such as network glitches, temporary unavailability of resources, or timeouts.

Explain a bit more

Why it’s important: It helps to recover from temporary failures that are often due to issues like network latency or service downtime. It enhances resilience and improves the user experience by reducing the impact of short-lived failures. Implementation:

Real-world example (ShopNest)

If Payment is down, the Order service fails fast with a circuit breaker instead of hanging every checkout thread.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: The Circuit Breaker pattern is used to detect and prevent failures from cascading through a system by stopping requests to a service that is known to be failing.

Explain a bit more

How it helps resilience: When a service starts failing, the circuit breaker trips and prevents further requests from being made to the failing service. This helps to protect the rest of the system and gives the failing service time to recover. It improves system stability by avoiding repetitive failures that would otherwise cause further damage or delays. Implementation:

Real-world example (ShopNest)

If Payment is down, the Order service fails fast with a circuit breaker instead of hanging every checkout thread.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.