220-1201 Virtualization and Cloud Computing Study Guide for the CompTIA A+ Core Series Exam

General Information

Cloud computing has only increased in use during the years since the last edition of the CompTIA A+ Core Series exam. Even though only about 11% of the questions on the CompTIA A+ 1201 exam pertain to this field, it will be important to be thoroughly familiar with the subject. You’ll need to be able to compare and contrast ideas in cloud computing and also be able to set up virtualization for the client. It is worth noting that none of the questions in this area begin with a scenario for you to evaluate when answering. The study key here is to really know these terms and their functionality.

Virtualization

Virtualization is the process of creating software or hardware in a virtual, or strictly logical, environment. For the CompTIA A+ exam, you will need to identify, understand, and explain common virtualization concepts.

Virtual Machine (VM) Purposes

A VM is designed to remove the one-to-one hardware and software barrier and maximize available resources. VMs can be used to run multiple OSs on a single device or can pool resources from multiple servers into a single powerful system. VMs can also be used to protect the host system by separating the VMs from one another.

Sandbox

A sandbox is a temporary, isolated virtual environment that can be used for testing or quarantining. A sandbox creates a safe environment separated virtually from the host machine to eliminate the potential contamination of the host machine. Data in the sandbox is only in the sandbox and does not save to the host. When the sandbox is terminated, all data associated with the sandbox is also removed.

Test Development

VMs can be used for test development by creating virtual environments and operating systems (OSs) that can be used for application testing or development.

Application Virtualization

The virtualization of applications is often used with legacy software or legacy OS to offer the functionality of the legacy application. Application virtualization is also used for cross-platform functionality. For example, an application designed for macOS can be used on a Windows machine by creating a virtual macOS on the Windows machine.

Legacy Software/Operating System

Legacy software and OSs are outdated software and operating systems that are not compatible with modern systems.

Cross-Platform Virtualization

Cross-platform virtualization is the process of creating a virtual OS of one platform on a different platform, such as macOS on Windows OS.

Requirements

Not all virtual machines are created equal. The individual who is building the VM determines what resources to provide it. This means determining the amount of hard drive space and the amount of memory that your local machine can afford to give the VM, because VMs can require considerable resources. If your physical machine doesn’t have a lot of random-access memory (RAM), then you will not be able to provide enough RAM for your VM to run smoothly.

Security

Just as security is vital in physical computing, it’s also important to consider security when working with VMs. This means implementing the same types of security controls on your virtual desktops as you would on your physical ones, such as strong passwords, account lockout policies, and even multi-factor authentication.

Network

Network requirements for virtualization are dependent on the scope of the virtual network. Networking requirements for more advanced systems include hypervisors (discussed in greater detail below), which are used to manage the virtual network infrastructure, and management and/or controller software, which is used to manage the virtual network and associated policies and configurations.

Storage

As with network requirements, storage requirements vary based on the scope and use of the virtual network. Storage space is allocated to each individual virtual device depending on need. Dynamic allocation (or real-time as needed) refers to the storage of resources and is highly useful in more sophisticated virtual networks to ensure that storage space is available when needed.

Desktop Virtualization

Thanks to virtualization, it’s possible to have multiple virtual desktops running on one physical machine. These machines operate similarly to a physical desktop, but all the hardware is virtualized. You must be able to summarize these concepts.

Virtual Desktop Infrastructure (VDI)

A VDI is a means of managing virtual desktops. With a VDI on premises, the virtual machine running the virtual desktops is located on the physical premises of the entity using it. A VDI removes the physical hardware of a network, such as switches, cables, and network interface cards (NICs), and replaces them with virtual hardware contained on a single machine located at the site.

VDI in the cloud removes the virtual machine from the physical premises and places it in the cloud environment run through cloud providers. This eliminates the user’s responsibility for the physical hardware running the VDI.

Containers

A container is a virtual environment that is used to house applications and their associated software in a separate environment using the underlying OS kernel, unlike a VM, which creates the entire OS. A container provides a more simplistic and efficient deployment over VMs. Containers require significantly fewer resources than a VM, allowing for multiple containers to be hosted on a single kernel. Containers are also useful for software isolation and portability due to their compact nature.

Hypervisors

A hypervisor is a logical device that is used to host multiple virtual machines, each with separate and independent operating systems, on a single hardware server. The hypervisor sits between the VMs and the underlying hardware, allocating resources and facilitating communications between the VMs and the underlying hardware infrastructure. A hypervisor can be created on any computing device compatible with the hypervisor software, such as Hyper-V on the Windows OS. A hypervisor can be used to host multiple VMs by first choosing to create a new virtual machine, then naming and choosing the OS to be installed, allocating resources, and, finally, installing the identified OS. There are two types of hypervisors, Type 1 and Type 2.

Type 1

A Type 1 hypervisor, also known as a bare metal hypervisor, allows VMs direct access to the underlying host infrastructure and resources.

Type 2

A Type 2 hypervisor sits on top of the host OS, preventing the VMs from having direct communication and access to the underlying infrastructure and resources.

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Cloud Computing

For this exam, it is important to understand cloud computing and the different types of cloud-computing offerings that exist. You should also be able to summarize entire processes.

Before cloud computing, scalability was difficult, as users were always restricted by their local resources. A common example of cloud computing includes online file storage. Online file storage allows users to store documents, photos, and videos in the cloud without needing to take up storage on their local hard drive. However, cloud computing covers far more than just file storage. It’s now possible to move an entire organization’s infrastructure, including everything from servers to networking equipment, to the cloud.

Cloud Models

Common cloud models include the different types of cloud structures that can be used as well as service structures that can be offered within the cloud environment. Cloud services are often sold as a service. When choosing a cloud model, there are numerous factors to consider and steps to take, beginning with evaluating the desired requirements, then choosing an appropriate provider, allocating resources, and applying the appropriate security measures prior to the go-live phase (launch). While there are numerous cloud models, you should be familiar with the common cloud models.

Private Cloud

A private cloud is a cloud model in which the virtualization resources purchased by the user are dedicated solely to the use of the user. This ensures the greatest level of security for the user but comes at an increased price as well as less flexibility for the resources. Think of a cloud as a physical file cabinet. With a private cloud, only the user is able to access or store their information in the file cabinet.

Public Cloud

A public cloud is a virtualization resource in which the resource is shared across the open internet. This means that the same cloud server that contains a user’s data also contains the data of anyone else who uses that service. Imagine the physical file cabinet again. With a public cloud, you are able to store your data in a separate file within the file cabinet, but the files of thousands of other people are also stored in the same file cabinet. For this reason, a public cloud is not as secure as a private cloud. An example of a public cloud would be Dropbox or iCloud.

Hybrid Cloud

A hybrid cloud is a mixture of the public cloud and the private cloud. A portion of the data is stored in a public cloud, while other, more sensitive data can be stored in a private cloud. A hybrid cloud offers the security of a private cloud for more sensitive data as well as the flexibility and scalability of a public cloud.

Community Cloud

A community cloud is a cloud that is shared between a specific set of users. Imagine the file cabinet again. The file cabinet is shared between users, but only a specific set of users can store their data in the file cabinet, increasing security over a public cloud, which allows for anyone to store data in the file cabinet.

Infrastructure as a Service (IaaS)

IaaS can be thought of as a virtual data center. As its name suggests, infrastructure as a service providers allow clients to build their entire infrastructure in the cloud. Infrastructure includes items such as servers, firewalls, routers, and switches. In an IaaS environment, clients are entirely responsible for managing, maintaining, and patching operating systems and applications.

Software as a Service (SaaS)

In recent years, there has been a major shift from locally installed software to web-based software. SaaS has become a popular choice for organizations because it allows them to access their programs anywhere an internet connection is available. SaaS can be described as any program that is accessed via the web and not locally installed.

Platform as a Service (PaaS)

PaaS provides a platform for developers to build their own applications. PaaS providers handle everything on the back end, including servers, operating systems, and development tools. This allows developers to focus on creating, building, and managing their applications.

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Cloud Characteristics

Cloud characteristics are features available on the cloud. You must be able to summarize these common features.

Shared Resources

Shared resources, also known as resource pooling, is the division of the resources of the provider among the clients of that provider. One physical host machine with a lot of resources (memory, storage capacity) can have its resources shared among multiple virtual machines. This resource sharing can occur both internally and externally. A dedicated resource is a physical or virtual element, such as storage, that is used only by a single entity. Dedicated resources allow for isolation, increased security, and increased control over the dedicated resource as opposed to shared resources.

Metered Utilization

Metered utilization refers to the concept of tracking a cloud user’s usage and charging only for the number of services used. With most metered utilizations, ingress (incoming data) is not charged for, while egress (outgoing data) is metered and charged for.

Note: The terms “measured service” and “metered service” are commonly used interchangeably when referring to cloud computing. The National Institute of Standards and Technology publication, SP 800-145, “The NIST Definition of Cloud Computing,” characterizes a measured service as when “cloud systems automatically control and optimize resource use by leveraging a metering capability at some level of abstraction appropriate to the type of service (e.g., storage, processing, bandwidth, and active user accounts). Resource usage can be monitored, controlled, and reported, providing transparency for both the provider and consumer of the utilized service.”

Above information retrieved from NIST SP 800-145, “The NIST Definition of Cloud Computing”.

Elasticity

It’s not always clear how much of a particular resource you are going to need when setting up a new environment. It’s entirely possible (and quite common) for your resource needs to grow as the organization grows. An organization that started with five servers might triple its server needs in several years. Virtualization makes it possible to quickly add new servers as you need them without the hassle of purchasing new hardware each time. This is known as elasticity.

Availability

Availability is the concept of a cloud service being uninterrupted and responsive the majority of the time. Service-level availability or uptime is measured in nines. For example, a provider with three nines of availability has 99.9% uptime, while a provider with five nines of availability guarantees 99.999% uptime.

File Synchronization

File synchronization is the ability to provide the most recent copy of data on both the cloud and local devices through the synchronization process.

Multitenancy

Multitenancy occurs when a single cloud instance is used by multiple entities with their data logically separated from one another. For example, public clouds such as Amazon Web Services (AWS) or Google Cloud use multitenancy.