AWS/Cloud

Question 1

How does S3 achieve durability and availability?

Answer 1

• Durability – 99.999999999% (11 nines), achieved by storing multiple copies of data across multiple Availability Zones (AZs).
• Availability – 99.99% uptime for standard storage, meaning data is accessible most of the time.
• Replication – S3 replicates objects automatically to avoid data loss from hardware failures.

Question 2

What is the difference between IAM roles, policies, and users?

Answer 2

• Users – Individual identities with long-term credentials (username/password, access keys).
• Roles – Temporary identities with specific permissions, assumed by AWS services or other users (who you are in AWS (temporary identity with a purpose).)
• Policies – JSON documents defining what actions are allowed/denied on which AWS resources. (what you’re allowed to do (the permissions list))

Question 3

What is the difference between a public subnet and a private subnet in AWS?

Answer 3

• A public subnet is a part of your AWS network where resources can connect directly to the internet (like a web server people can access).
• A private subnet is a part of your network where resources cannot directly access the internet and are kept isolated for security (like a database or backend server).
• Common use: web servers in public subnet, databases in private subnet.

Question 4

Explain how an AWS Load Balancer works.

Answer 4

• Distributes incoming requests to servers
• Improves fault tolerance, scalability, and performance.

Types:

• Round Robin: Distributes traffic sequentially to each server in a pool.
• Weighted Round Robin: Similar to Round Robin, but servers are assigned weights, influencing how often they receive traffic.
• IP Hash: Uses the client’s IP address to consistently route requests to the same server.
• Random: Selects a server randomly.

Question 5

What is the difference between API Gateway and an Application Load Balancer?

Answer 5

• API Gateway – rate limits, authenticate.
• ALB – routes API request to correct server
• Think: API Gateway = API management, ALB = web traffic distribution.

Question 6

What is an AWS VPC, and why would you use one?

Answer 6

• VPC – Virtual Private Cloud; your isolated network in AWS.
• Lets you control IP ranges, subnets, route tables, gateways, and security groups.
• Used to separate workloads, improve security, and control network traffic.

Question 7

Lambda

Answer 7

• Definition: A serverless compute service that runs your code in response to events, automatically managing servers and scaling.
• Origami use: Processing a file upload to S3 (e.g., validating policy data).

Question 8

EC2

Answer 8

• Scalable, virtual machines
• Definition: A service that provides resizable virtual machines in the cloud to run applications.
• Origami use: Hosting backend services or legacy apps that need full control.

Question 9

EKS

Answer 9

• Elastic Kubernetes Service
• Definition: A managed service that runs Kubernetes clusters on AWS without you having to install or maintain Kubernetes yourself.
• Origami use: Deploying and scaling containerized microservices like claims, billing, and workflow engines.

Question 10

S3 (Simple Storage Service)

Answer 10

• Simple Storage Service
• Definition: An object storage service that lets you store and retrieve any amount of data with high durability and availability.
• Origami use: Storing client-uploaded documents, backups, logs.

Question 11

RDS

Answer 11

• Managed relational databases (Postgres, MySQL, SQL Server).
• Origami use: Storing structured policy, claims, and workflow data.

Question 12

DynamoDB

Answer 12

• Serverless NoSQL database
• Origami use: Fast access to unstructured or semi-structured client data.

Question 13

IAM

Answer 13

• Manage AWS users, roles, and permissions

Question 14

VPC

Answer 14

• Virtual Private Cloud
• VPC is your private network in AWS where you run your stuff safely

Question 15

Route 53

Answer 15

• Domain name and DNS service
• Origami use: Maps domain names to resources (like EC2 instances, load balancers, S3 buckets, or CloudFront distributions).

Question 16

CloudFront

Answer 16

• CDN for delivering files quickly worldwide
• Origami use: Serving app assets to global clients with low latency

Question 17

CloudWatch

Answer 17

• Logs, metrics, and alerts
• Origami use: Detecting slow API responses or failed background jobs

Question 18

CloudTrail

Answer 18

API-level audit logs

Question 19

Athena

Answer 19

Serverless service to query data

Question 20

Glue

Answer 20

ETL service

Question 21

Redshift

Answer 21

Fully managed data warehouse

Question 22

Kinesis

Answer 22

Streaming data (similar to Kafka)

Question 23

SNS

Answer 23

Simple Notification Service (pub-sub broadcast system for events)