CompTIA Network+ Preparation · lesson 23 of 30 · 25 min
Cloud Service Models
Cloud computing delivers computing resources (servers, storage, networking, software) over the internet on a pay-as-you-go basis.
IaaS (Infrastructure as a Service) — provider supplies virtualized hardware (VMs, storage, networking). Customer manages OS, middleware, and applications. Examples: AWS EC2, Azure VMs, Google Compute Engine.
PaaS (Platform as a Service) — provider supplies the platform (OS + runtime + middleware). Customer manages applications and data only. Examples: AWS Elastic Beanstalk, Azure App Service, Google App Engine.
SaaS (Software as a Service) — provider supplies the complete application. Customer just uses it. Examples: Microsoft 365, Salesforce, Google Workspace.
Cloud Deployment Models
Public cloud — resources shared among multiple customers (multi-tenant). Managed by a cloud provider. Cost-effective, scalable. Examples: AWS, Azure, GCP.
Private cloud — dedicated infrastructure for one organization. On-premises or hosted. More control and security. Higher cost.
Hybrid cloud — combination of public and private cloud. Sensitive workloads on private; scalable workloads on public. Connected via VPN or dedicated link.
Community cloud — shared infrastructure for organizations with common requirements (e.g., government agencies, healthcare). Less common on the exam.
Virtualization
Virtualization — running multiple virtual machines (VMs) on a single physical host using a hypervisor.
Type 1 hypervisor (bare-metal) — runs directly on hardware. No host OS. Examples: VMware ESXi, Microsoft Hyper-V, Xen. Better performance — used in data centers.
Type 2 hypervisor (hosted) — runs on top of a host OS. Examples: VMware Workstation, VirtualBox. Easier to set up — used for development/testing.
Containers — lightweight virtualization at the OS level. Share the host OS kernel. Faster startup, less overhead than VMs. Examples: Docker, Kubernetes. Not full isolation — all containers share the kernel.
SDN (Software-Defined Networking) — separates the control plane (routing decisions) from the data plane (packet forwarding). Centralized controller manages the network programmatically. Enables automation and flexibility.
NFV (Network Functions Virtualization) — replaces physical network appliances (routers, firewalls, load balancers) with software running on commodity hardware.
Exam Tip
IaaS/PaaS/SaaS: remember what the customer manages. Type 1 hypervisor = bare-metal (data center). Type 2 = hosted (desktop). Containers share the host OS kernel — less isolation than VMs.
Key Terms
Key Terms
Knowledge Check — 10 Questions
Network+ — Cloud and Virtualization
In IaaS, the customer is responsible for managing:
- Physical hardware
- The hypervisor
- The OS, applications, and data
- The cloud provider’s network
- Answer: The OS, applications, and data
IaaS: provider manages hardware and hypervisor. Customer manages OS, middleware, applications, and data. Microsoft 365 is an example of:
- IaaS
- PaaS
- SaaS
- DaaS
- Answer: SaaS
SaaS = complete application delivered over the internet. Microsoft 365, Salesforce, and Google Workspace are SaaS examples. A Type 1 hypervisor runs:
- On top of a host OS
- Directly on hardware (bare-metal)
- Inside a container
- On a virtual machine
- Answer: Directly on hardware (bare-metal)
Type 1 (bare-metal) hypervisors run directly on hardware — no host OS. Examples: VMware ESXi, Hyper-V. Used in data centers for performance. Containers differ from VMs because containers:
- Require more resources
- Share the host OS kernel
- Have better security isolation
- Cannot run on cloud platforms
- Answer: Share the host OS kernel
Containers share the host OS kernel — much lighter than VMs. Faster startup, less overhead, but less isolation.
SDN separates which two planes?
- Physical and virtual
- Control plane and data plane
- Management and user plane
- Layer 2 and Layer 3
Answer: Control plane and data plane
SDN separates the control plane (routing decisions, centralized controller) from the data plane (packet forwarding on switches/routers).
A hybrid cloud combines:
- Two public clouds
- Public and private cloud
- IaaS and SaaS
- Two data centers
- Answer: Public and private cloud
Hybrid cloud = public + private. Sensitive workloads stay on private cloud; scalable/variable workloads use public cloud. NFV replaces physical network appliances with:
- Hardware ASICs
- Software running on commodity hardware
- Cloud-only services
- Dedicated fiber links
- Answer: Software running on commodity hardware
NFV virtualizes network functions (firewalls, routers, load balancers) as software on standard x86 servers — reduces hardware costs.
VirtualBox is an example of which hypervisor type?
- Type 1 (bare-metal)
- Type 2 (hosted)
- Type 3 (container)
- Type 0 (firmware)
Answer: Type 2 (hosted)
VirtualBox and VMware Workstation are Type 2 hypervisors — they run on top of a host OS (Windows, macOS, Linux).
In a public cloud, resources are:
- Dedicated to one organization
- Shared among multiple customers (multi-tenant)
- Always on-premises
- Only available via private WAN
- Answer: Shared among multiple customers (multi-tenant)
Public cloud is multi-tenant — resources are shared among many customers, with logical isolation. This enables economies of scale.
PaaS provides the platform (OS + runtime) so customers only manage _____ and data.
Answer: applications
PaaS: provider manages OS, runtime, middleware. Customer manages applications and data only — no OS patching needed.
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