Data Center Virtualization and Cloud Infrastructure Concepts
What to know
Data center virtualization and cloud concepts describe the architecture on which VMware products sit. Virtualization abstracts compute, storage, and networking so that resources are pooled and allocated by policy; the software-defined data center (SDDC) extends this abstraction to the whole data center and automates it. Know the layers: compute virtualization (ESXi and vSphere), storage virtualization (vSAN, Virtual Volumes), network virtualization (NSX), and the management and automation layer.
Cloud literacy is equally testable. Distinguish service models: IaaS delivers infrastructure such as VMs, storage, and networks; PaaS delivers a runtime and platform services; SaaS delivers finished applications. Distinguish deployment models: private cloud is dedicated to one organization; public cloud is provider-owned and multi-tenant; hybrid cloud integrates private and public with common management and workload portability; multi-cloud uses more than one public provider. VMware Cloud and VMware Cloud Foundation are common answers when a question asks how on-premises and cloud environments are operated consistently.
Traps
Candidates conflate virtualization with cloud: virtualization is a technology, while cloud is an operating model with self-service, elasticity, and metering. Scalability (capacity can grow) is not elasticity (capacity scales automatically with demand). RTO is the target time to restore service; RPO is the acceptable amount of data loss measured in time - mix them up and DR questions flip. Also watch for "hybrid" used loosely when the scenario is really multi-cloud.
Rule of thumb
For any disaster-recovery scenario, write two sentences before choosing an answer: "How much data can we lose?" (RPO, which drives replication frequency) and "How long can we be down?" (RTO, which drives the recovery method). Worked example: an RPO of 15 minutes and an RTO of 1 hour point to frequent replication and a warm standby, not nightly backups.