Foundational Concepts and Terminology
This domain tests whether you can speak the vocabulary precisely, because most missed questions are vocabulary collisions rather than deep technical failures.
Core building blocks
Every environment you will be asked about is a stack of layers: physical or virtual compute, storage, networking, and the software that binds them. Know the difference between virtualization (a hypervisor abstracts hardware; each guest carries its own OS) and containerization (a shared kernel isolates processes; images are small and start fast). Know the service models: with IaaS you still own the guest OS, patching, and runtime; with PaaS you own only the application and its data; with SaaS you own only your configuration and your data. Deployment models (public, private, hybrid, multi-cloud) describe who owns and shares the infrastructure, not what runs on it.
Also be fluent in: availability expressed in nines, latency versus throughput, scalability (capacity can grow) versus elasticity (capacity grows and shrinks automatically with demand), stateful versus stateless components, and the shared responsibility model.
Traps that show up in questions
- Scalability vs elasticity - adding capacity manually is scaling; automatic demand-following is elasticity.
- High availability vs disaster recovery - HA absorbs component failure inside one site; DR survives loss of the site.
- IaaS vs PaaS boundaries - if the answer requires you to patch an operating system, you are almost certainly in IaaS territory.
- Backup vs replication - replication copies deletions and corruption faithfully; a backup does not.
Rule of thumb
Ask "who patches the operating system?" If it is you, it is IaaS or on-premises. If it is the provider, you are at PaaS or above. That single question resolves most service-model questions.