Cloud Engineering

IaaS gives raw infrastructure (VMs, networks); PaaS gives a managed platform to deploy code (App Service, Cloud Run); SaaS is finished software (Gmail, Salesforce). Each step up means less to manage but less control.

A VPC is your private, isolated network in the cloud. Subnets divide it into IP ranges; public subnets route to the internet, private subnets do not.

Defining infrastructure in version-controlled files (e.g. Terraform). It makes environments repeatable, reviewable, testable and easy to recreate.

Run multiple instances across availability zones behind a load balancer, use managed databases with replicas, health checks, autoscaling and automated failover.

Vertical adds more CPU/RAM to one machine; horizontal adds more machines. Horizontal scaling is preferred for resilience and elasticity.

Block public access, use least-privilege IAM policies, enable encryption and versioning, turn on access logging and use private endpoints where possible.

Security groups are stateful firewalls attached to resources; network ACLs are stateless rules applied at the subnet level.

Rightsize instances, shut down idle resources, use autoscaling, reserved or savings plans for steady workloads, spot instances for flexible jobs, and storage lifecycle policies.

RTO is how quickly you must restore service after a failure; RPO is how much data loss (in time) is acceptable. They drive backup and DR design.

Serverless suits spiky, event-driven workloads with little ops overhead; containers suit long-running services, custom runtimes or steady high traffic where cost and control matter.