Cloud fundamentals

The foundational papers from Microsoft, AWS and Oracle open with the same material because nothing later makes sense without it. Azure Fundamentals gives cloud concepts a whole section of its own, and that section reads like a glossary with decisions attached. Learn these terms as consequences, not definitions, and the associate exams become easier to reason through.

• Service models. With IaaS you rent machines, disks and networks and run everything above the operating system. With PaaS the platform runs your code and keeps the runtime current. With SaaS you simply use finished software. Each step up hands more work, and more control, to the provider.
• Deployment models. Public clouds serve any paying customer; private ones serve a single organisation; hybrid estates join the two with networking and shared identity. NIST adds a fourth, the community cloud, shared by organisations with common obligations.
• Regions and availability zones. A region is a geographic area; a zone is an isolated group of data centres inside it with separate power and cooling. Spreading across zones survives a building failure; surviving the loss of an entire region takes a second region and a plan.
• Elasticity and scalability. Scalability means a system can grow. Elasticity means it grows and shrinks on its own as demand moves, which is only true once someone configures it.
• Consumption pricing. You pay for what runs, measured in seconds, requests or gigabytes, instead of buying capacity in advance.

The split that decides who fixes what

AWS describes security as divided in two: the provider answers for the infrastructure the cloud runs on, and the customer answers for whatever they put into it. Some controls are inherited outright, such as physical security of the halls. Some are shared, such as patching, where the provider patches its hosts and you patch your guest operating system. Some are yours alone. The line is not fixed. On a virtual machine you own nearly everything above the hypervisor; on a managed database or a storage service, the provider takes the engine and you keep access rights, encryption choices and the data itself. The defence of that customer half is a field of its own, which the cybersecurity silo treats under cloud security.

Where to take this next depends on your goal. Azure Fundamentals and Cloud Practitioner certify exactly this vocabulary on their own platforms, and OCI Foundations does the same without a fee. Anyone who already works in IT can often skip the paper and go straight to an associate exam, but not the content: the associate questions assume every term above and use them without explanation. The cloud platforms topic then translates these ideas into each vendor's product names, and governance and landing zones shows how an estate is divided into accounts, subscriptions or projects before the first workload arrives.