Peer-to-Peer NetworksComputers did not wake up one day and hooked up to the Internet. The firstpractical networks for personal computers were peer-to-peer networks. A peer-to-peer network is a small group of computers with a common purpose allconnected to each other. This small network allowed a single printer to be usedby any computer on the network and computers could also share information.These types of networks were frequently called Local Area Networksor LANs.Initially, the networks were true peer-to-peer networks. This means that everycomputer on the network was equal. All computers were personal computerwork stations. Chapter I Introduction to Computer Science Page 35
Cient-Server NetworksPeer-to-peer networks do not work well when networks get large. Special,dedicated computers, called servers, were needed. A server is a specialtycomputer that is connected to the LAN for one or more purposes. Servers can beused for printing, logon authentications, permanent data storage, web sitemanagement and communication. Many businesses would have multiple serversset up in such a manner that some servers exist for the purpose of backing up theprimary server. Using backup systems, tape storage or other backup meansinsured computer reliability in case of computer failure. The Department Of Defense Networking RoleIt may come as a shock to you, but the Internet was not created so that teenagerscould play video games and download music. The Internet has its origins in the"Cold War." If you do not know what the "Cold War" is ask your Social Studiesteacher, your parents or any old person over 30. During the Cold War there wasa major concern about the country being paralyzed by a direct nuclear hit on thePentagon. It used to be that all military communications traveled through thePentagon. If some enemy force could knock out the Pentagon, the rest of themilitary establishment communication would be lost. A means ofcommunication had to be created that was capable to keep working regardless ofdamage created anywhere. This was the birth of the Internet. The Internet hasno central location where all the control computers are located. Any part of theInternet can be damaged and all information will then travel around the damagedarea.The Modern InternetStudents often think that the Internet is free. Well that would be lovely, butbillions of dollars are invested in networking equipment that needs to be paid insome fashion. Computers all over the world are first connected to computerswithin their own business or school. Normally, businesses and schools have aseries of LANs that all connect into a large network called an Intranet. AnPage 36 Exposure Java 2009, PreAPCS Edition 08-09-09
Intranetbehaves like the Internet on a local business level. This promotessecurity, speed and saves money.