Cloud and Emerging Technologies
This domain covers cloud service and deployment models, the shared responsibility split, and how virtualisation, containers and newer platforms change who manages what.
Core rules
- NIST essentials - on-demand self-service, broad network access, resource pooling, rapid elasticity, measured service.
- Service models - IaaS gives you virtual machines: you patch the guest OS upward. PaaS gives a managed runtime: you manage the app and data. SaaS gives a finished application: you manage users, data and configuration.
- Shared responsibility - the provider secures the cloud itself (facilities, hardware, hypervisor); the customer secures what they put in it. The split moves with the service model.
- Deployment - public, private, hybrid, community.
- Elasticity vs availability - elasticity matches capacity to demand automatically; high availability survives component failure. They are different promises.
- Virtualisation and containers - a type 1 hypervisor runs on bare metal, type 2 is hosted. Containers share the host kernel, so they start faster and isolate less than VMs. Serverless bills per invocation and leaves scaling to the provider.
Worked example
A team needs a custom application with OS-level tuning and automatic scaling. Reasoning: IaaS with a managed database fits, because they need control of the guest OS. If they only needed email and document collaboration, SaaS would be correct and would shift patching entirely to the provider.
Traps that cost marks
- Assuming the provider patches the guest OS under IaaS - it does not.
- Using elasticity and high availability interchangeably.
- Forgetting data egress and storage charges when estimating cost.