1.1 - Cloud service models (IaaS, PaaS, SaaS, serverless)
Cloud+ CV0-004 objective 1.1 covers cloud service and deployment models. The models differ by how much the provider manages. With IaaS you rent bare virtual machines and manage the OS, patches and apps yourself. With PaaS the provider manages the OS and runtime while you deploy your application and data. With SaaS the provider runs the whole application and you just use it. Serverless (FaaS) runs event-driven code with no servers to manage, paying only per execution. Multitenancy means multiple customers share the same physical infrastructure while their data stays logically isolated. You should also know public, private, hybrid and community deployment models. Expect scenario questions that describe who manages which layer or how resources are shared, and ask which service model - IaaS, PaaS, SaaS or serverless - or which concept the situation matches.
Bare VMs, you patch the OS = IaaS. Provider runs OS/runtime, you deploy the app = PaaS. Whole app, you just use it = SaaS. Event code, no servers, pay per run = serverless (FaaS). Shared infra, isolated data = multitenancy.
Practice questions
1. In which service model does the provider manage the OS and runtime while you deploy only your application code?
- IaaS
- PaaS (correct answer)
- SaaS
- DaaS
PaaS gives you a managed platform (OS, runtime, middleware); you supply code. IaaS gives raw VMs (you manage the OS); SaaS is a finished app.
2. An organization runs sensitive workloads on-prem and bursts to a public cloud during peaks. This is a:
- Public cloud
- Private cloud
- Hybrid cloud (correct answer)
- Community cloud
A hybrid cloud combines private (on-prem) and public clouds with orchestration between them - ideal for cloud bursting. Community cloud is shared by related organizations.
3. A retailer places compute in a carrier-neutral facility to interconnect directly with several providers. What is this facility called?
- Availability zone
- Edge cache node
- Colocation datacenter (correct answer)
- Managed PaaS region
A colocation facility rents rack space in a carrier-neutral datacenter, giving low-latency cross-connects to many networks and clouds. It is not owned by one provider.
4. A team wants to run event-driven code without managing any servers, paying only per execution. Which model fits?
- Dedicated hosting
- Managed VMs
- Serverless (FaaS) (correct answer)
- Bare-metal cluster
Serverless / Function as a Service runs short functions on demand; the provider handles all servers and you pay per invocation and runtime. Managed VMs still bill while idle.
5. Several agencies in the same sector share a cloud built to their common compliance rules. This is a:
- Public cloud
- Private cloud
- Community cloud (correct answer)
- Hybrid cloud
A community cloud is shared by organizations with common requirements (regulatory, mission). A public cloud is open to all tenants; a private cloud serves one organization.
6. In which model do you rent bare virtual machines and manage the OS, patches and apps yourself?
- IaaS (correct answer)
- PaaS
- SaaS
- FaaS
IaaS gives raw compute, storage and network; you manage the guest OS upward. PaaS abstracts the OS and runtime; SaaS delivers a finished application.