Cloud Computing Concepts | CompTIA A+ 220-1001 | 4.1

In this video you will learn about various cloud computing concepts such as:  Infrastructure as a Service, Software as a Service, Platform as a Service, shared resources, rapid elasticity, on-demand self-service, resource pooling, measured services, metered services, off-site email applications, cloud file storage services, virtual application streaming/cloud-based applications, and virtual desktops.

Common Cloud Models

Cloud computing is the on-demand availability of computer system resources, especially data storage (cloud storage) and computing power, without direct active management by the user.  The term is generally used to describe data centers available to many users over the internet.  Cloud computing comes in 3 main models which we will discuss in further detail:  

  • IaaS (Infrastructure as a Service)
  • SaaS (Software as a Service)
  • PaaS (Platform as a Service)
Cloud Computing Models


Infrastructure as a Service (IaaS), also known as cloud infrastructure services, is a form of cloud computing in which IT infrastructure is provided to end users through the internet.  IaaS is commonly associated with serverless computing.  The IaaS vendor provides the virtualization, storage, network, servers, and allows for customers to utilize/pay for virtual resources when they are needed.  This cloud computing model allows for customers to not have to have an on-premise datacenter and not worry about physically updating or maintaining these components themselves.  Most importantly, this model allows for companies to reduce the costs of their network infrastructure by outsourcing storage & computing services to a cloud provider.  IaaS puts users in charge of all the software used in a project, from applications and data to the operating system.  IaaS vendors supply the hardware and network support tools.  The three largest cloud providers at the time of this writing are:

  • Amazon Web Services (AWS)
  • Microsoft Azure
  • IBM


Software as a Service (SaaS) is a software licensing and delivery model in which software is licensed on a subscription basis and is centrally hosted.  SaaS applications are also known as web-based software, on-demand software and hosted software.  Because SaaS processing is performed at the server, a thin client, smartphone, or tablet is sufficient to run the software.   A browser-based service that does not require a user to download application code to use the service is an example of SaaS.  SaaS allows organizations to get quickly up and running without having to develop or deploy an application.  Examples of SaaS applications are:

  • Gmail:  Provides access to email services via Google.
  • Google Drive:  Provides access to word processing, spreadsheets, presentations, & various other forms.
  • Microsoft Office 365:  Provides access to word processing, spreadsheets, presentations, calendars, email, etc.
  • Salesforce:  A customer relationship management application.


Platform as a Service (PaaS) is a category of cloud computing services that provides a platform allowing customers to develop, run, and manage applications without the complexity of building and maintaining the infrastructure typically associated with developing and launching an app.  A developer using PaaS can concentrate on software features instead of possible issues with server hardware and operating systems.  Some of the major PaaS vendors include:

  • Oracle Cloud
  • Google Cloud Platform
  • Microsoft Azure
  • Salesforce Platform
Cloud Computing Pizza Analogy

Public vs. Private vs. Hybrid vs. Community

Cloud computing comes in four general categories:

  • Public Cloud Computing:  Defined as computing services offered by 3rd-party providers over the public internet, making them available to anyone who wants to use or purchase them.  They may be free or sold on-demand, allowing customers to pay only per usage for the CPU cycles, storage, or bandwidth they consume.
  • Private Cloud Computing:  Defined as computing services offered over the internet or a private internal network & only to select users instead of the general public.  Private cloud computing is considered to be more secure than public cloud computing.
  • Hybrid Cloud Computing:  A computing environment that combines public cloud & a private cloud by allowing data and applications to be shared between them.  When computing and processing demand fluctuates, hybrid cloud computing gives organizations the ability to seamlessly scale their on-premises infrastructure up to the public cloud to handle any overflow — without giving 3rd-party datacenters access to the entirety of their data.
  • Community Cloud Computing:  A collaborative effort in which infrastructure is shared between several organizations from a specific community with common concerns (security, compliance, jurisdiction, etc), whether managed internally or by a 3rd-party and hosted internally or externally.  This is controlled and used by a group of organizations that have shared interest.  The costs are spread over fewer users than a public cloud (but more than a private cloud), so only some of the cost savings potential of cloud computing are realized.

Shared Resources

In computing, a shared resource is a computer resource made available from one host to other hosts on a computer network.  It is a device or piece of information on a computer that can be remotely accessed from another computer transparently as if it were a resource in the local machine.  Sharing equipment or data on a network to save costs is the overall reason to implement cloud computing.  There are two main ways to share devices & data over the internet:  by way of an internal cloud or an external cloud.

Internal Cloud

An internal cloud (also known as a corporate cloud) is a cloud computing service that is implemented within an organization’s dedicated resources and infrastructure.  Internal clouds apply virtualization mechanisms, shared storage and network resources to facilitate full control of an organization’s cloud computing environment.  With an internal cloud, the company gets the virtualization services and flexibility of a commercial cloud but with the security and reliability that comes from existing within the company’s network infrastructure.  The costs often associated with an internal cloud typically are higher than utilizing a commercial cloud provider, but there are still reduced costs associated with sharing resources internally.

External Cloud

An external cloud is a cloud solution that exists outside of an organization’s physical boundaries.  It can be private, public or community-based, as long as it is not located on an organization’s property.  An external cloud would involve the sourcing of any cloud solution that’s available and can be used along with an internal cloud infrastructure or an internal cloud solution for any business need.  The services delivered through this kind of setup matches the services offered by a private cloud however the primary difference is that all physical resources are essentially external to the organization.

Rapid Elasticity

Rapid elasticity is a cloud computing term for scalable provisioning, or the ability to provide scalable services.  Rapid elasticity allows users to automatically request additional space in the cloud or other types of services.  Because of the setup of cloud computing services, provisioning can be seamless for the client or user.  In a sense, cloud computing resources appear to be infinite or automatically available.  That’s very different from older systems, where the limits of storage or memory were immediately visible to a user. 


On-demand computing (also known as on-demand self-service) is a business computing model in which computing resources are made available to the user on an “as needed” basis.  Rather than all at once, on-demand computing allows cloud hosting companies to provide their clients with access to computing resources as they become necessary.  Gmail is an example of an on-demand self-service where users can access their email online from virtually any device that connects to the internet anytime they want.

Resource Pooling

Resource pooling is an IT term used in cloud computing environments to describe a situation in which providers serve multiple clients, customers or “tenants” with provisional and scalable services.  These services can be adjusted to suit each client’s needs without any changes being apparent to the client or end user.

Measured Service

Measure service refers to how cloud services are monitored for quality and effectiveness.  Measuring service metrics can help drive decisions about what services to adopt and how to calculate pricing of services.

Metered Service

Measured service in a term that applies to cloud computing which is a reference to services where the cloud provider measures or monitors the provision of services for various reasons, including billing, effective use of resources, or overall predictive planning.  Cloud computing services are typically calculated on an hourly basis.  Outsourcing by the hour could result in huge savings for customers, and this feature is what has driven the high growth of cloud services.

Off-Site Email Applications

Off-site email applications allow for organizations to pay other companies like Google to manage all of the company’s email, in addition to managing the enormous amounts of data generated by all of this email.  Google Workspace (formerly known as G Suite) is an example of an off-site email application where organizations can pay Google a monthly subscription fee to essentially get an enhanced version of Google Drive & Gmail.  The alternative to off-site email is on-site email (also known as on-premise) which means that an organization is responsible for all of the costs associated with purchasing, powering, and maintaining the server equipment and the company’s LAN provides access to the on-site email applications.

Cloud File Storage Services

Cloud file storage is a method for storing data in the cloud that provides servers and applications access to data through shared file systems.  Cloud file storage services utilize cloud-based synchronization where apps on a mobile device send data to the cloud which can then be downloaded by other mobile apps, web browsers, or by programs running on Windows or macOS.  Examples of cloud file storage services are:

  • Google Drive
  • Dropbox
  • Apple iCloud
  • Microsoft OneDrive

Virtual Application Streaming/Cloud-Based Applications

Virtual application streaming refers to an on-demand software delivery model that works based on the fact that the majority of applications need just a small portion of their total programming code for operation. The applications are stored and run in the cloud and delivered to the user on almost any device, such as smartphones, tablets, laptops, and desktops.. This indicates that there is no need to fully install a program on a client machine.  However, portions of it could be offered across the network whenever required.  To implement virtual application streaming, a user purchases a license and downloads a small app that identifies the user.  The application is presented to the user as if it were locally installed, but only the essentials are brought down to the device.  Adobe Creative Cloud is an example of a virtual application (also a SaaS cloud-based application) that allows users to utilize apps like Adobe Photoshop without actually installing the program locally to their computer.

Virtual Desktop

Virtual desktop infrastructure (VDI) is defined as the hosting of desktop environments on a central server (or the cloud).  It is a form of desktop virtualization, as the specific desktop images run within a virtual machine (VM) and are delivered to end clients over a network.  Those endpoints may be PCs or other devices, like tablets or thin client terminals in which the mouse and keyboard inputs are sent across the internet..

Virtual NIC

A virtual network interface card (NIC) is an abstract virtualized representation of a computer network interface that may or may not correspond directly to a network interface controller.  Virtual NICs within a VM behave identical to that of a physical NIC in that it needs a physical MAC address & IP address in order to communicate with other machines.  The only real difference between a virtual NIC and a physical NIC is that an administrator can assign specific MAC addresses to a virtual NIC by way of a virtual machine manager (VMM) whereas on a physical NIC, the MAC address is assigned by the manufacturer.  If an admin wants the VM to communicate with other machines, they can create a path, or bridge, between the virtual NIC and the physical NIC on the VMM hardware.  This allows the VM to communicate like any other machine in the LAN.