1.0.5 - 1.3.4 Quiz Text.txt

The internet is not owned by any individual or group. The internet is a worldwide collection of interconnected networks (internetwork or internet for short), cooperating with each other to exchange information using common standards. Through telephone wires, fiber-optic cables, wireless transmission...

The internet is not owned by any individual or group. The internet is a worldwide collection of interconnected networks (internetwork or internet for short), cooperating with each other to exchange information using common standards. Through telephone wires, fiber-optic cables, wireless transmissions, and satellite links, internet users can exchange information in a variety of forms, as shown in the figure. Everything that you access online is located somewhere on the global internet. Social media sites, multiplayer games, messaging centers that provide email, online courses --- all of these internet destinations are connected to local networks that send and receive information through the internet. Think about all of the interactions that you have during the day which require you to be online. Local networks come in all sizes. They can range from simple networks consisting of two computers, to networks connecting hundreds of thousands of devices. Networks installed in small offices, or homes and home offices, are referred to as small office/home office (SOHO) networks. SOHO networks let you share resources such as printers, documents, pictures, and music, between a few local users. In business, large networks can be used to advertise and sell products, order supplies, and communicate with customers. Communication over a network is usually more efficient and less expensive than traditional forms of communication, such as regular mail or long distance phone calls. Networks allow for rapid communication such as email and instant messaging, and provide consolidation and access to information stored on network servers. Business and SOHO networks usually provide a shared connection to the internet. The internet is considered a "network of networks" because it is literally made up of thousands of local networks that are connected to each other. Small home networks connect a few computers to each other and to the internet. The internet connects more computing devices than just desktop and laptop computers. There are devices all around that you may interact with on a daily basis that are also connected to the internet. These include mobile devices, home devices, and a variety of other connected devices. Smartphones are able to connect to the internet from almost anywhere. Smartphones combine the functions of many different products together, such as a telephone, camera, GPS receiver, media player, and touch screen computer. Tablets, like smartphones, also have the functionality of multiple devices. With the additional screen size, they are ideal for watching videos and reading magazines or books. With on-screen keyboards, users are able to do many of the things they used to do on their laptop computer, such as composing emails or browsing the web. A smartwatch can connect to a smartphone to provide the user with alerts and messages. Additional functions, such as heart rate monitoring and counting steps, like a pedometer, can help people who are wearing the device to track their health. A wearable computer in the form of glasses, such as Google Glass, contains a tiny screen that displays information to the wearer in a similar fashion to the Head-Up Display (HUD) of a fighter pilot. A small touch pad on the side allows the user to navigate menus while still being able to see through the smart glasses. Many of the things in your home can also be connected to the internet so that they can be monitored and configured remotely. Many of the items in a home, such as security systems, lighting, and climate controls, can be monitored and configured remotely using a mobile device. Household appliances such as refrigerators, ovens, and dishwashers can be connected to the internet. This allows the homeowner to power them on or off, monitor the status of the appliance, and also be alerted to preset conditions, such as when the temperature in the refrigerator rises above an acceptable level. A smart TV can be connected to the internet to access content without the need for TV service provider equipment. Also, a smart TV can allow a user to browse the web, compose email, or display video, audio, or photos stored on a computer. Gaming consoles can connect to the internet to download games and play with friends online. There are also many connected devices found in the world outside your home that provide convenience and useful, or even vital, information. Many modern cars can connect to the internet to access maps, audio and video content, or information about a destination. They can even send a text message or email if there is an attempted theft or call for assistance in case of an accident. These cars can also connect to smartphones and tablets to display information about the different engine systems, provide maintenance alerts, or display the status of the security system. Radio frequency identification (RFIDs) tags can be placed in or on objects to track them or monitor sensors for many conditions. Connected sensors can provide temperature, humidity, wind speed, barometric pressure, and soil moisture data. Actuators can then be automatically triggered based on current conditions. For example, a smart sensor can periodically send soil moisture data to a monitoring station. The monitoring station can then send a signal to an actuator to begin watering. The sensor will continue to send soil moisture data allowing the monitoring station to determine when to deactivate the actuator. Medical devices such as pacemakers, insulin pumps, and hospital monitors provide users or medical professionals with direct feedback or alerts when vital signs are at specific levels. Types of Personal Data We hear about data all of the time. Customer data, personal data, health data, census data, but what exactly is data? Perhaps the simplest definition of data is that data is a value that represents something. In the physical world, we represent data as numbers, formulas, alphabetic characters, and pictures. Think about all of the data that exists just about you. Some examples include birth records, baby pictures, school records, and health records. Most people use networks to transmit their data in order to share with others, or for long-term storage. Every time you hit "send" or "share" in an app or computer application, you are telling your device to send your data to a destination somewhere on the network. Sometimes, data is being sent by your devices and you may not even be aware that this is happening. Examples of this are when you set up an automatic backup utility, or when your device automatically searches for the router in a Wi-Fi hotspot. The following categories are used to classify types of personal data: Volunteered data - This is created and explicitly shared by individuals, such as social network profiles. This type of data might include video files, pictures, text or audio files. Observed data - This is captured by recording the actions of individuals, such as location data when using cell phones. Inferred data - This is data such as a credit score, which is based on analysis of volunteered or observed data. Did you know that computers and networks only work with binary digits, zeros and ones? It can be difficult to imagine that all of our data is stored and transmitted as a series of bits. Each bit can only have one of two possible values, 0 or 1. The term bit is an abbreviation of "binary digit" and represents the smallest piece of data. Humans interpret words and pictures, computers interpret only patterns of bits. A bit is stored and transmitted as one of two possible discrete states. This can include two directions of magnetization, two distinct voltage or current levels, two distinct levels of light intensity, or any other physical system of two discrete states. For example, a light switch can be either On or Off; in binary representation, these states would correspond to 1 and 0 respectively. Every input device (mouse, keyboard, voice-activated receiver) will translate human interaction into binary code for the CPU to process and store. Every output device (printer, speakers, monitors, etc.) will take binary data and translate it back into human recognizable form. Within the computer itself, all data is processed and stored as binary. Computers use binary codes to represent and interpret letters, numbers and special characters with bits. A commonly used code is the American Standard Code for Information Interchange (ASCII). With ASCII, each character is represented by eight bits. For example: Capital letter: A = 01000001 Number: 9 = 00111001 Special character: \# = 00100011 Each group of eight bits, such as the representations of letters and numbers, is known as a byte. Codes can be used to represent almost any type of information digitally including computer data, graphics, photos, voice, video, and music. In the figure, enter up to five characters in the Characters field, then click the Show Me button to see the ASCII bit translation. Click Reset to enter a different group of characters. Common Methods of Data Transmission After the data is transformed into a series of bits, it must be converted into signals that can be sent across the network media to its destination. Media refers to the physical medium on which the signals are transmitted. Examples of media are copper wire, fiber-optic cable, and electromagnetic waves through the air. A signal consists of electrical or optical patterns that are transmitted from one connected device to another. These patterns represent the digital bits (i.e. the data) and travel across the media from source to destination as either a series of pulses of electricity, pulses of light, or radio waves. Signals may be converted many times before ultimately reaching the destination, as corresponding media changes between source and destination. There are three common methods of signal transmission used in networks: Electrical signals - Transmission is achieved by representing data as electrical pulses on copper wire. Optical signals - Transmission is achieved by converting the electrical signals into light pulses. Wireless signals - Transmission is achieved by using infrared, microwave, or radio waves through the air. Click Play in the figure to see an animation of the three types of signal transmissions. In most homes and small businesses, network signals are transmitted across copper wires (cables) or Wi-Fi enabled wireless connections. Larger networks employ fiber-optic cables in order to reliably carry signals for longer distances. Bandwidth Streaming a movie or playing a multiplayer game requires reliable, fast connections. To support these "high bandwidth" applications, networks have to be capable of transmitting and receiving bits at a very high rate. Different physical media support the transfer of bits at different speeds. The rate of data transfer is usually discussed in terms of bandwidth and throughput. Bandwidth is the capacity of a medium to carry data. Digital bandwidth measures the amount of data that can flow from one place to another in a given amount of time. Bandwidth is typically measured in the number of bits that (theoretically) can be sent across the media in a second. Common bandwidth measurements are as follows: Thousands of bits per second (Kbps) Millions of bits per second (Mbps) Billions of bits per second (Gbps) Physical media properties, current technologies, and the laws of physics all play a role in determining available bandwidth. The table shows the commonly used units of measure for bandwidth. Table caption Unit of Bandwidth Abbreviation Equivalence Bits per second bps 1 bps = fundamental unit of bandwidth Kilobits per second Kbps 1 Kbps = 1,000 bps = 103 bps Megabits per second Mbps 1 Mbps = 1,000,000 bps = 106 bps Gigabits per second Gbps 1 Gbps = 1,000,000,000 bps = 109 bps Terabits per second Tbps 1 Tbps = 1,000,000,000,000 bps = 1012 bps Throughput Like bandwidth, throughput is the measure of the transfer of bits across the media over a given period of time. However, due to a number of factors, throughput does not usually match the specified bandwidth. Many factors influence throughput including: The amount of data being sent and received over the connection The types of data being transmitted The latency created by the number of network devices encountered between source and destination Latency refers to the amount of time, including delays, for data to travel from one given point to another. Throughput measurements do not take into account the validity or usefulness of the bits being transmitted and received. Many messages received through the network are not destined for specific user applications. An example would be network control messages that regulate traffic and correct errors. In an internetwork or network with multiple segments, throughput cannot be faster than the slowest link of the path from sending device to the receiving device. Even if all or most of the segments have high bandwidth, it will only take one segment in the path with lower bandwidth to create a slowdown of the throughput of the entire network. There are many online speed tests that can reveal the throughput of an internet connection.