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AWS Certified Cloud Practitioner — Free Essentials

Key facts distilled from CertKata's CLF-C02 question bank. Free to read — no account needed.

Six benefits of cloud computing

Trade capital expense (CapEx) for variable expense (OpEx); benefit from massive economies of scale; stop guessing capacity (elasticity); increase speed and agility; stop spending on running/maintaining data centers; go global in minutes. Elasticity = scaling automatically with demand, both up and down; scalability is the broader ability to add capacity.

Shared Responsibility Model

Shared responsibility model: providers are always responsible for physical and host infrastructure, customers are always responsible for their data and access configuration, and the exact boundary shifts with the service modelPROVIDERalways responsible forPhysical facilitiesHostinfrastructureVirtualizationlayerCUSTOMERalways responsible forDataIdentity &accessResourceconfigurationIaaSPaaSSaaSshown at PaaS — shifts toward IaaS or SaaS

AWS is responsible for security "OF" the cloud: physical facilities, hardware, network, virtualization infrastructure. The customer is responsible for security "IN" the cloud: their data, IAM configuration, guest OS (for IaaS), and how they use each service. Managed services (like RDS) shift more of the operational burden — like patching — onto AWS.

Global infrastructure: Region / AZ / Edge

Region and availability zone hierarchy: a region contains multiple availability zones, each backed by one or more data centersREGIONAZ-1Data centerData centerAZ-2Data centerData centerAZ-3Data centerData centereach AZ: one or more independent data centers

A Region is a geographic area containing multiple Availability Zones (AZs); each AZ is one or more discrete data centers with independent power/cooling/networking. Spreading across AZs protects against a single data center failure. Edge locations (used by CloudFront/Route 53) cache content close to users — separate from Regions/AZs.

EC2 pricing models

On-Demand: pay by the hour/second, no commitment. Reserved Instances: 1- or 3-year commitment for a big discount. Spot: spare capacity at steep discount, can be reclaimed by AWS with short notice — for interruption-tolerant workloads. Savings Plans: commit to $/hour of compute usage, more flexible than RIs (covers EC2, Fargate, Lambda).

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