Domain 1: Cloud Concepts (24% of the exam) Most questions in this domain describe a scenario and ask which benefit or concept it shows. For each term, learn what it means and which keywords point to it. 1. The basics Cloud computing is the on-demand delivery of IT resources (compute, storage, databases, applications) over the internet, with pay-as-you-go pricing. AWS owns the hardware, and you provision what you need, when you need it. Deployment model What it is Question keywords --------- Private Used by one organization, not public, full control "single organization", "full control of sensitive apps" Public Run by a third-party provider over the internet (AWS, Azure, GCP) The six advantages apply Hybrid Part on-premises, part in the cloud "split between on-premises and AWS" The exam guide calls these three models cloud (cloud-native), hybrid and on-premises. Five characteristics (NIST): On-demand self-service: you provision resources without contacting the provider. Broad network access: resources are reachable over the network from any client. Resource pooling: customers share hardware but are isolated from each other (multi-tenancy). Rapid elasticity: resources scale out and in quickly and automatically. Measured service: usage is metered, and you pay for what you use. 2. The six advantages ★ Advantage Meaning Question keywords --------- Trade fixed expense for variable expense (CAPEX → OPEX) Pay for usage instead of buying hardware "upfront", "capital", "pay as needed" Benefit from massive economies of scale AWS's size lowers its costs, so its prices are lower "aggregate usage", "lower prices", "lower variable cost" Stop guessing capacity Capacity follows actual demand "scale with load", "over-/under-provisioning" Increase speed and agility Resources in minutes, so experiments are cheap "minutes, not weeks", "experiment", "time to market" Stop spending money running and maintaining data centers Focus on your business, not on racking and powering servers "data center costs", "focus on customers" Go global in minutes Deploy to Regions worldwide in a few clicks "new countries", "lower latency for global users" Other benefit terms Term Meaning ------ Scalability Handles more load, either with a bigger instance (vertical, scale up) or more instances (horizontal, scale out) Elasticity Scales out and in automatically with demand Agility New resources arrive fast, so you can build, test and launch quickly Flexibility You can change resource types when needed High availability Minimal downtime, achieved by running across multiple AZs Fault tolerance Keeps running with no interruption when a component fails Don't mix these up If the question says… Answer ------ Pay for actual usage, no upfront cost Pay-as-you-go pricing if it's an option; otherwise "trade fixed for variable expense" Lower prices because of AWS's size Economies of scale (never speed or capacity) Scales out and in automatically, spiky traffic Elasticity Minutes instead of weeks, experimenting Agility, not elasticity Capacity matches demand, phrased as an advantage Stop guessing capacity TCO (Total Cost of Ownership) is the full cost of running IT: hardware, software, facilities, power, staff and maintenance. The cloud lowers it, so "lower TCO" on the exam points to cloud economics. 3. Service models Model AWS manages You manage Example ------------ IaaS Hardware, networking, virtualization OS, runtime, data, apps Amazon EC2 PaaS Everything up to the runtime Data and apps AWS Elastic Beanstalk SaaS Everything Nothing but your data and who can access it Amazon Rekognition, Gmail, Zoom FaaS All servers Your function code AWS Lambda Moving from IaaS to PaaS to SaaS, you get less control and less work, and more of the security responsibility shifts to AWS. 4. Pricing and cloud economics You pay for three things: compute time, storage, and data transfer out. Data transfer in is free. Bills even when idle: EBS volumes (including on stopped instances), snapshots, public IPv4 addresses, load balancers, NAT gateways, running databases. Free: IAM, VPCs, subnets, security groups, empty S3 buckets, Lambda functions that don't run. Term Meaning ------ CAPEX vs OPEX An upfront asset purchase vs ongoing operating spend Fixed vs variable cost A cost that stays the same whether used or not vs a cost that follows usage License-included vs BYOL The license cost is built into the hourly price vs you bring licenses you already own Managed service AWS handles infrastructure, patching and scaling (RDS, DynamoDB, Lambda), so your team has less to do Rightsizing Matching instance size to actual usage Automation (IaC) Infrastructure as code (CloudFormation), which is repeatable and reduces errors Costs that go away after migrating: data center rent, power, cooling, physical security, and buying and refreshing hardware. Costs and duties that stay with you: software licenses, your staff, outbound data transfer, backups, DR planning, compliance, security configuration. 5.…