A network consists of two or more computers that are linked in order to share resources (such as printers and CDs), exchange files, or allow electronic communications. The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams. Two very common types of networks include:
You may also see references to a Metropolitan Area Networks (MAN), a Wireless LAN (WLAN), or a Wireless WAN (WWAN). Local Area NetworkA Local Area Network (LAN) is a network that is confined to a relatively small area. It is generally limited to a geographic area such as a writing lab, school, or building. Computers connected to a network are broadly categorized as servers or workstations. Servers are generally not used by humans directly, but rather run continuously to provide "services" to the other computers (and their human users) on the network. Services provided can include printing and faxing, software hosting, file storage and sharing, messaging, data storage and retrieval, complete access control (security) for the network's resources, and many others. Workstations are called such because they typically do have a human user which interacts with the network through them. Workstations were traditionally considered a desktop, consisting of a computer, keyboard, display, and mouse, or a laptop, with with integrated keyboard, display, and touchpad. With the advent of the tablet computer, and the touch screen devices such as iPad and iPhone, our definition of workstation is quickly evolving to include those devices, because of their ability to interact with the network and utilize network services. Servers tend to be more powerful than workstations, although configurations are guided by needs. For example, a group of servers might be located in a secure area, away from humans, and only accessed through the network. In such cases, it would be common for the servers to operate without a dedicated display or keyboard. However, the size and speed of the server's processor(s), hard drive, and main memory might add dramatically to the cost of the system. On the other hand, a workstation might not need as much storage or working memory, but might require an expensive display to accommodate the needs of its user. Every computer on a network should be appropriately configured for its use. On a single LAN, computers and servers may be connected by cables or wirelessly. Wireless access to a wired network is made possible by wireless access points (WAPs). These WAP devices provide a bridge between computers and networks. A typical WAP might have the theoretical capacity to connect hundreds or even thousands of wireless users to a network, although practical capacity might be far less. Nearly always servers will be connected by cables to the network, because the cable connections remain the fastest. Workstations which are stationary (desktops) are also usually connected by a cable to the network, although the cost of wireless adapters has dropped to the point that, when installing workstations in an existing facility with inadequate wiring, it can be easier and less expensive to use wireless for a desktop. See the Topology, Cabling, and Hardware sections of this tutorial for more information on the configuration of a LAN. Wide Area NetworkWide Area Networks (WANs) connect networks in larger geographic areas, such as Florida, the United States, or the world. Dedicated transoceanic cabling or satellite uplinks may be used to connect this type of global network. Using a WAN, schools in Florida can communicate with places like Tokyo in a matter of seconds, without paying enormous phone bills. Two users a half-world apart with workstations equipped with microphones and a webcams might teleconference in real time. A WAN is complicated. It uses multiplexers, bridges, and routers to connect local and metropolitan networks to global communications networks like the Internet. To users, however, a WAN will not appear to be much different than a LAN. Advantages of Installing a School NetworkUser access control. Modern networks almost always have one or more servers which allows centralized management for users and for network resources to which they have access. User credentials on a privately-owned and operated network may be as simple as a user name and password, but with ever-increasing attention to computing security issues, these servers are critical to ensuring that sensitive information is only available to authorized users. Information storing and sharing. Computers allow users to create and manipulate information. Information takes on a life of its own on a network. The network provides both a place to store the information and mechanisms to share that information with other network users. Connections. Administrators, instructors, and even students and guests can be connected using the campus network. Services. The school can provide services, such as registration, school directories, course schedules, access to research, and email accounts, and many others. (Remember, network services are generally provided by servers). Internet. The school can provide network users with access to the internet, via an internet gateway. Computing resources. The school can provide access to special purpose computing devices which individual users would not normally own. For example, a school network might have high-speed high quality printers strategically located around a campus for instructor or student use. Flexible Access. School networks allow students to access their information from connected devices throughout the school. Students can begin an assignment in their classroom, save part of it on a public access area of the network, then go to the media center after school to finish their work. Students can also work cooperatively through the network. Workgroup Computing. Collaborative software allows many users to work on a document or project concurrently. For example, educators located at various schools within a county could simultaneously contribute their ideas about new curriculum standards to the same document, spreadsheets, or website. Expensive to Install. Large campus networks can carry hefty price tags. Cabling, network cards, routers, bridges, firewalls, wireless access points, and software can get expensive, and the installation would certainly require the services of technicians. But, with the ease of setup of home networks, a simple network with internet access can be setup for a small campus in an afternoon. Requires Administrative Time. Proper maintenance of a network requires considerable time and expertise. Many schools have installed a network, only to find that they did not budget for the necessary administrative support. Servers Fail. Although a network server is no more susceptible to failure than any other computer, when the files server "goes down" the entire network may come to a halt. Good network design practices say that critical network services (provided by servers) should be redundant on the network whenever possible. Cables May Break. The Topology chapter presents information about the various configurations of cables. Some of the configurations are designed to minimize the inconvenience of a broken cable; with other configurations, one broken cable can stop the entire network. Security and compliance. Network security is expensive. It is also very important. A school network would possibly be subject to more stringent security requirements than a similarly-sized corporate network, because of its likelihood of storing personal and confidential information of network users, the danger of which can be compounded if any network users are minors. A great deal of attention must be paid to network services to ensure all network content is appropriate for the network community it serves.
1 2 Internet...? Definition: The Internet is millions of computers around the world connected to each other. Explanation: When you're on the Internet, your computer is connected to others by networks of telephone wire, cable and satellite. The Web, e-mail, chat, and newsgroups are things you can do on the Internet. 3 How do computers communicate? Think about all of the computers that are connected here at school. Such a group of computers is called a network. Computers in a network can communicate with one another. All of these networks are connected to one another in a huge worldwide network called the Internet. The Internet is made of millions of computers around the world. Most communicate through copper wires or glass fibers. Others communicate through the air, like cell phones do. Being connected is not enough. Computers must also understand one another. They must speak the same language in order to communicate. Computers connected to the Internet exchange instructions that allow them to “talk” to one another. People, schools and businesses own different parts of the Internet. These parts include computers, cables, and other equipment. Nobody owns the whole Internet. The Internet is shared. Anyone who pays a fee can use it. Everyone owns it. 4 What Cyberspace Is Cyberspace is where people like you exchange ideas using computers that are connected to the Internet. It is real people communicating with other real people. In cyberspace, your adventures are real. You can have real fun and learn a lot. But, it is also possible to get into very real trouble. Hanging out with people you meet in cyberspace is not the same as being with people you know for real – your family, friends, teachers, and coaches. 5 Be Comfortable It is fun to explore Web sites and search for information. However, sometimes you may find things you don’t want to see. It’s easy to stumble across icky or embarrassing sites by mistake. In fact, some sites have tricky addresses on purpose. So remember, “It’s not your fault.” When you get that uncomfortable feeling at a Web site, get out of there. Click the back button on your browser. Then tell your parent, guardian, or teacher and allow them to click on the site to gather necessary information to prevent this from happening to others. 6 People Change in Cyberspace Most people have good manners face to face, but use rude words in cyberspace. They think in cyberspace it is okay to say things that they’d never say to someone face to face. Why? Maybe they think they can’t get in trouble in cyberspace. Maybe they think it makes them seem cool, or maybe when they’re behind a computer screen they just forget they’re talking to a real person. If someone on the street makes you uncomfortable, you know to walk away and tell an adult. The same rule works in cyberspace. Ignore them, block them, or get offline, but make sure you tell an adult. 7 It’s Okay to Chat and IM Remember that cyberpals are not face to face friends. You only know them from chatting on line. You can have good talks, sharing feelings, talking about problems that you might not want to share with friends at school. BUT, can you be sure that you really know if a cyberpal is male or female, your age or much older. The answer is NO. That’s the main difference between a cyberpal and a friend you know face to face. So always treat cyberpals as strangers. Never give them private information about yourself. 8 Be Cybersmart! Know the kinds of information that are private: Full name Street address Name of school School address E-mail address Phone number Passwords Calling card number Mother’s maiden name Parent’s place of work Photos in which you can be recognized Photos with school logos 9 Online Talk – Dos and Don’ts Do stick to monitored chat rooms for kids. Don’t use screen names that tell your name, age, or whether you’re a boy or a girl. Don’t use screen names that are suggestive. Don’t go into private, unmonitored chat rooms. Since instant messaging is like private chat, do use it only with family and friends. Don’t relax so much that you accidentally give out private identity information. Don’t flirt with strangers. Don’t answer questions that make you uncomfortable. Remember to listen for that inner alarm bell. Do respond to the question “Are you alone:” with “NO” even if you are alone. Do tell your parent or guardian if someone bothers you. Let them know if the person might have your private identity information. Never plan to meet face-to-face with someone you met in a chat room. 10 Cyberspace Chatting Checklist My parents say it’s okay for me to chat in cyberspace. I will only go into chat rooms for kids that have monitors. I will never reply to, or click on a link in an IM from someone who is not a face-to-face friend. I will pick chat and messaging screen names that are different from my E-mail address. My screen name does not tell my name, age, or whether I am a boy or girl 11 I know what kinds of information are private. I will not give out private information when chatting. I will not answer questions that make me uncomfortable. I will tell a trusted adult if someone bothers me in cyberspace. I will never meet someone face-to-face that I met in a chat room. I will never share my password with anyone, not even my best friend. Remember you are at the controls and it is your responsibility to practice safety on the Internet. |
Does the Internet connects millions of computers and resources across the world via wires cables and satellite?
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