Page 2 902 Other Operating Systems and Technologies Study Guide for the CompTIA® A+ exam

Client-Side Virtualization

Virtualization allows you to run multiple operating systems simultaneously from a single computer. You may see these questions posed to you as a customer scenario on the A+ exam.

  • Purpose of Virtual Machines: Virtual machines allow multiple different operating systems to be run on a single computer. This requires virtualization software that will create individual virtual machines, each capable of running a different operating system. This requires that the host machine has adequate system resources to support each virtual machine. This is often done to support multiple servers running on a single platform, which saves energy and lowers the hardware cost.

  • Resource Requirements: A host computer running virtual machines must have a processor capable of supporting virtual machines and provide adequate system resources such as memory and hard drive space to each virtual system it supports.

  • Emulator Requirements: An emulator is used when you want to run an application on a device on which it was never intended to run. The program may have been written to run on Windows XP and you need to run it on Windows 7. Emulation usually does not run as well due to the overhead needed. You need to know the difference between virtualization and emulation.

  • Security Requirements: You are expected to have a working knowledge of security relating to all aspects of virtualization.

  • Network Requirements: Virtual machines can be set up with their own virtual network that allows communications among other systems on the network, or anywhere.

  • Hypervisor: This is the software that allows the creation of virtual machines, with each appearing as separate systems.

Cloud Concepts

Cloud computing has radically changed the way in which applications are made and deployed through a network. Cloud concepts is a new exam objective added in the 902 exam. You will be required to identify the following basic cloud concepts.

  • SaaS (Software as a Service): SaaS is a cloud service where you are using software you use on demand, typically not locally stored, but rather on the Internet.

  • IaaS (Infrastructure as a Service): IaaS is a cloud service where you are using someone else’s hardware with your own software.

  • PaaS (Platform as a Service): PaaS is a cloud service where you are provided software and hardware, typically used in developing applications.

  • Public vs. Private vs. Hybrid vs. Community: A public cloud deployment provides services to anyone. Private cloud deployment is when the cloud is internal to a company. Hybrid cloud deployment is a mix between public and private clouds. Community cloud is when several organizations share the same infrastructure and resources.

  • Rapid Elasticity: This allows cloud users to increase and/or decrease cloud resources, as needed.

  • On-Demand: These services are made available to users without delays.

  • Resource Pooling: The resources are shared (pooled) across multiple entities to share/reduce cost.

  • Measured Service: This service has metered billing, as delivered to the customer.

Networked Hosts

You need to have a working understanding of the properties and purpose of network delivered services in a client-server environment. Know the difference between a client application and a server application. Client applications request services from a server application.

Server Roles

You are expected to have a working understanding of the following network services. A server is not necessarily a stand-alone piece of hardware. A server is usually a process running in memory on a networked system that responds to requests from a remote client system.

  • Web Server: a web-based server that typically uses HTTP (hypertext transfer protocol), or possibly FTP (file transfer protocol) to respond to requests from a client

  • File Server: the repository of shared data files in a client-server model

  • Print Server: a network attached device that manages print requests

  • DHCP Server: dynamic host configuration protocol server used to assign the necessary network parameters to hosts on a network, such as IP address and subnet information

  • DNS Server (domain name system server): used to resolve a domain name into an IP address

  • Proxy Server: an intermediary device between the Internet and users; a dedicated system that locally stores often used Internet sites; improves response time and provides security

  • Mail Server: an application that acts as a message transfer agent (MTA) to send and receive e-mail on a network

  • Authentication Server: an application that provides authentication to users attempting to log into a network

Internet Appliance

An Internet appliance is one of many devices that facilitate Internet access, such as cell phones, tablets, gaming systems, etc.

  • UTM (Unified Threat Management): an all-inclusive network security system that provides intrusion detection, anti-malware, firewall, and content filtering

  • IDS (Intrusion Detection System): a tool used to monitor network security and detect threats, but cannot take direct action to stop the threats

  • IPS (Intrusion Prevention System): a tool used to monitor network security, but can also respond to these threats directly to prevent security breaches, unlike an IDS

Legacy/Embedded Systems

Many organizations maintain older systems for a variety of reasons. One reason would be to run a program that was never ported to later platforms.

Mobile Operating Systems

You will be expected to have a working understanding of the various features of cell phones and other mobile devices, including Apple IOS, Google Android, and Windows Mobile operating systems.

  • Open source vs. closed source/vendor specific: Open source operating systems like Google Android are designed to allow access to the source code. This makes it easy to incorporate on a number of different platforms. Apple IOS is closed source, making it proprietary to Apple systems only.

  • App source: Software for various devices are available from different sources such as Apple’s App Store, Google Play, Microsoft’s Windows Store, or third-party applications from the Amazon App Store.

  • Screen orientation: Built into most mobile devices is an accelerometer and gyroscope feature, working to provide location information as well as up/down orientation for the screen.

  • Screen calibration: Earlier mobile devices incorporated resistive touchscreens that required occasional recalibration. Newer devices use capacitive touchscreens that have the advantage of accuracy and do not require recalibration.

  • GPS and geotracking: Global positioning is used to precisely calculate latitude and longitude for mapping applications. This can be accomplished using WiFi signals or triangulating nearby cell towers.

  • WiFi calling: When incorporated, this feature allows incoming and outgoing calls to be made using a WiFi connection rather than a cell tower.

  • Launcher/GUI: Cell phones have small icons used to launch applications.

  • Virtual assistant: Incorporated in newer devices is a virtual assistant that will respond to spoken requests. Apple uses Siri, Windows uses Cortana, and Android uses OK Google to activate the assistant.

  • SDK/APK: SDK is a software development kit allowing the creation of mobile apps. APK is an Android application package format.

  • Emergency notification: Emergency alerts are directed to cell phones to inform users of emergency situations. This feature has been recently added to all newer mobile devices.

  • Mobile payment service: This service allows mobile devices to make purchases.