4.1 - Cloud concepts and characteristics
CompTIA A+ Core 1 objective 4.1 covers cloud concepts and characteristics. In the SaaS model the provider manages everything and you simply use the application over the web. Measured service, or pay-as-you-go, means you are billed only for the compute and storage you actually use, with no idle-server cost. Rapid elasticity means capacity automatically scales up under demand - a retailer growing for Black Friday and shrinking afterward - and back down when it is no longer needed. Other traits include on-demand self-service, broad network access and resource pooling. Expect scenario questions that describe how a cloud service is billed, scales or is delivered and ask which characteristic or model - SaaS, measured service or elasticity - it demonstrates. These characteristics describe how a cloud behaves, separate from the service model itself.
Provider runs the whole app, you just use it = SaaS. Pay only for what you use = measured service (pay-as-you-go). Auto scale up and down with demand = rapid elasticity.
Practice questions
1. Resources are dedicated to a single organization in its own isolated cloud. Which deployment model is this?
- Public cloud
- Private cloud (correct answer)
- Hybrid cloud
- Community cloud
A private cloud is dedicated to one organization. Public is shared/multitenant; hybrid mixes both; community is shared by similar orgs.
2. In IaaS, who is responsible for patching the guest operating system?
- The cloud provider
- Nobody
- The customer (correct answer)
- The ISP
Under the shared responsibility model, in IaaS the customer manages the OS, apps and data; the provider handles the physical infrastructure.
3. Which cloud concept delivers full desktops to users from central servers?
- A content delivery network (CDN)
- VDI (Virtual Desktop Infrastructure) (correct answer)
- Network-attached storage (NAS)
- The domain name system (DNS)
VDI hosts user desktops on central servers, streamed to thin clients/devices — easy management and security.
4. A service that automatically copies a laptop's files to the cloud as they change is an example of:
- Local disk imaging
- Cloud file sync/backup (correct answer)
- A local virtual machine
- Disk defragmentation
Cloud sync/backup services (OneDrive, Google Drive) keep files copied and versioned in the cloud automatically.
5. A startup pays only for the seconds its code runs, with no servers to manage. This best describes:
- Traditional on-premises hosting
- Serverless, pay-per-use cloud (correct answer)
- A private company data center
- A legacy mainframe system
Serverless billing is metered/pay-per-use: you pay only for actual execution, with the provider managing servers.
6. A company pays only for the compute time its functions actually use, with no servers to manage. Which cloud characteristic does this describe?
- Measured/metered usage (correct answer)
- High availability
- Resource pooling
- On-premises hosting
Paying only for what you consume is metered/measured service — a core cloud characteristic (pay-as-you-go).