A plus 220-1101 – Exam Objective 4.1

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A+ Exam Objective 4.1 Compare and contrast cloud computing concepts.

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Welcome to ExamNotes by CertBlaster! In this edition, we will examine the Cloud and the wealth of services available through it. A quick caution; when you are examining services, there is a tendency in the sales community to use Cloud terminology/buzzwords to describe traditional services in order to make them sound updated. You will not find these terms discussed here or on the test, but you may encounter them in life or business.

We will first look at the Cloud service categories as defined by the National Institute of Standards and Technology (NIST). Next, we will look at the types of services available and some of the methods used to make hardware, applications, databases, and even operating systems run online.

Common cloud models

Private Cloud

A Private Cloud is internal to a company or organization and provides access only to those on the premises or connected via VPN. Private Clouds are the most secure type.

Public Cloud

The Public Cloud is available to all parties over the Internet. There are numerous companies providing publicly accessible services such as email and storage.

Hybrid Cloud

A Hybrid Cloud is a combination of public and/or private Cloud networks. These are often offered by hosting providers along with dedicated hosting.  A company may use the private internal Cloud for the storage of confidential communication and the external Cloud for email and web services.

Community Cloud

A Community Cloud is used by a collaborative group that shares resources for a common goal. This could be a medical group, insurance company, or any group of entities that has a shared objective. These Cloud types tend to be bigger than Private Clouds but smaller than the Public Cloud.

Here is a graphic representation of the main Cloud computing types.

Cloud computing public – private

 Cloud services are hosted and managed by third-party entities that provide most of the hardware and software required to access their services on demand. These services need to be broadly accessible and must provide resource pooling. Storage needs to provide rapid elasticity and be capable of measured service. There are several service models which are used to describe the level of service the provider and the customer are responsible for. Think of Cloud service categories as a stack of service models, with the lowest layers providing the foundation of total vendor management responsibility. Here is an example.

Cloud services


IaaS stands for Infrastructure as a Service.  IaaS is at the foundation in terms of vendor responsibility. The vendor supplies virtual access to the hardware, including virtual servers that can run the customers, server software, and applications on demand. This configuration also can be used to host websites and email servers. As the name implies, the vendor supplies the Infrastructure and the customer supplies the applications and data. Depending on the agreement, the vendor may or may not supply the operating system(s).


SaaS stands for Software as a Service. In this case, the vendor supplies and manages everything from the hardware to the applications that are used. This is a total solution as users and developers alike can access and modify the content. Different Cloud computing types offer different levels of accessibility as you will see next.


PaaS stands for Platform as a Service. It is quite similar to IaaS but provides two additional value-added services, making it the second layer in the Cloud Services model. For example, consider a platform for collaborative software development that maximizes the workflow regardless of the data source of an application. This means dissimilar sources can be used and proprietary application data can be used in the creation of software. This type of platform is useful for supporting multiple developers and automating the testing process.

Cloud Requirements

In order to qualify as a Cloud compatible service, the Infrastructure, Platform, and Software must meet the NIST guidelines listed below. These guidelines are the minimum requirement as additional services can be provided by a Cloud service.

Rapid Elasticity

Rapid Elasticity is the ability of a Cloud solution to scale its service level to meet the demand. This can take the form of adding storage space or user capacity seamlessly without interruption or the need to physically change hardware.

High Availability

High availability is used to describe a service that is available at any time. The redundancy that is available to Cloud-based solutions makes 100% availability (uptime) a reality.

Resource pooling

Resource pooling allows providers to share and spread the available resources across multiple consumers or companies. Resources are scaled dynamically and imperceptibly to each user as needed. This provides the maximum utilization of resources while providing the expected levels of service.

Measured / Metered service

Measured service is the practice of analyzing, measuring, or metering the number of resources used by an individual or organization. This is used for billing or for capping instances of over-the-limit consumption. This covers quantifiable elements such as bandwidth, storage, or other services.

File synchronization

Cloud storage is available from the major OS and mobile device manufacturers. iCloud provided by Apple, Google Drive by Google, and Microsoft’s OneDrive are a few well-known examples.

Each cloud storage option uses a proprietary sync app based on your account. The synced data can be accessed using a browser and your account information. This synched data can include files and email. There are also third-party sync apps that will work with several cloud storage services.

Virtual application streaming/cloud-based applications

Cloud-based applications use software installed only on the cloud server. These apps are accessed through a web browser without requiring any local installation.

A hybrid form of this technology is streaming where a small portion of the app is installed locally and the majority of the process is running on the cloud. This allows a streaming app to set up the connection and its parameters locally, enabling quality adjustments to be made based on the connection properties.

Virtual desktop infrastructure – VDI

A virtual desktop can be provided as part of a cloud infrastructure, or on-premises. In this case, the cloud service provider’s hypervisor presents a virtual desktop to a client using Virtual Desktop Infrastructure (VDI). This desktop will perform according to the base configuration and any modifications called for by the user’s credentials. This is considered to be a persistent VDI.

Once connected, the integration is seamless and the user is not limited in their capabilities. When a hypervisor allows guest or non-credentialed access, the VDI will consist of a generic configuration and any changes will not be saved. This is considered to be a non-persistent VDI.

That’s all for sub-objective 4.1! Good luck on the test!

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