Cloud Concepts

What the cloud actually changes

Cloud computing is the on-demand delivery of IT resources over the internet with pay-as-you-go pricing. The exam tests the consequences of that sentence more than the sentence itself: what changes about capacity, cost and speed once hardware stops being something you buy in advance.

Exam tip. When a question stresses UNCERTAIN demand, the answer is elasticity. When it stresses TIME TO TRY something, the answer is agility.

Regions, zones and the edge

AWS is laid out as Regions containing Availability Zones, with edge locations and other edge sites extending reach beyond them. Almost every infrastructure question is really asking which of those three layers is appropriate.

Exam tip. Region selection weighs four things: latency, compliance and residency, service availability, and price. Service availability is the one candidates forget.

The Well-Architected Framework

Six pillars of questions used to surface trade-offs in a workload's design. The framework does not rank the pillars: where two conflict, the answer is to make the trade-off explicit against the business requirement.

Exam tip. Reliability asks did it recover. Operational Excellence asks did we know, and could we tell why. That distinction separates the two most-confused pillars.

Migration strategies and the adoption framework

CAF prepares the organisation; the seven Rs decide what happens to each application. A migration is a portfolio of decisions rather than one action, and different applications get different answers.

Exam tip. Dual running is the real migration cost. The saving arrives when the old estate is switched OFF, so a programme that never decommissions costs more than it replaced.

Availability, resilience and disaster recovery

Availability is bought, not given. The business states how much data it can lose and how long it can be down, and those two numbers select the architecture.

Exam tip. Availability is limited by the least redundant component in the request path. Two web servers in front of one single-zone database is a single-zone design.

1. Which outcome best describes the financial change the company experiences?

• A. Capital expenditure is replaced by variable operating expenditure, and they stop paying for idle peak capacitycorrect
• B. Total spend is guaranteed to fall because AWS hardware is cheaper than the servers they were buying
• C. Capital expenditure stays the same but is spread across a longer depreciation period
• D. They pay a fixed annual fee that covers any amount of usage

The shift is from capital expenditure, buying assets up front and sizing them for the peak, to variable operating expenditure, paying for what is actually consumed. The guarantee that total spend will fall is the trap: AWS does not promise a lower bill, and a badly-run workload can easily cost more. What changes is that idle peak capacity stops being something you buy in advance.

2. What is the value of freeing staff from routine infrastructure maintenance?

• A. Software delivery becomes automatic
• B. Their time moves to work that differentiates the businesscorrect
• C. The headcount cost disappears from the accounts
• D. Maintenance stops being necessary anywhere

The benefit is redeployment rather than removal: the same people work on things customers notice. Patching does not vanish either, since anything the customer runs on EC2 remains theirs to maintain.