 client  client/server network  communication hardware  extranet  firewall  hacker  Internet  intranet  local area network (LAN)  Network  Server  wide area network (WAN) 2 22

 A group of two or more computers linked together that allows users to share software applications and hardware devices such as printers, scanners, and other hardware.  Used to connect people all over the world.

◦ Information sharing  Share information, data, and resources ◦ Collaborative environment  Users can work together ◦ Hardware sharing  Example: all of the computers on a network can print to a single printer ◦ Software sharing ◦ Enhanced communications  -messages are able to travel in seconds

◦ Individual loss of autonomy  Some software programs are inaccessible (Example: Your school/district network prevents Facebook, Twitter, etc.) ◦ Malicious code  Viruses, worms, Trojan horses, bombs, and spyware ◦ Loss of data or resources ◦ Setup and management costs ◦ is not necessarily private

 Networks are divided into two main types: 1.Local area networks (LANs) 2.Wide are networks (WANs)

 Local Area Networks: ◦ Most LANs connect personal computers, workstations, and other devices such as printers and scanners in a limited geographical area such as office buildings, school, or home ◦ Wireless LAN (WLAN)  A LAN that uses no physical wires

 Wide Area Networks: ◦ WANs covers a large geographical area and can contain communication links across metropolitan, regional, or national boundaries. Area can be as large as a state, country or even the world. They are connected by routers.  Network types include: ◦ Client/server network: Server manages resources ◦ Peer-to-peer network: All computers are equal ◦ Intranet: Used within an organization ◦ Extranet: Specific outside users can access ◦ Internet: Global network allows worldwide connection The Internet is an example of a WAN. Remember it’s the largest network.

 Communication Hardware:  Communication hardware devices facilitate the transmitting and receiving of data. Examples are: ◦ Modem: Converts analog signals to digital and vice versa ◦ Cable modem: Uses coaxial cable to send and receive data ◦ Digital subscriber line: Uses ordinary phone lines ◦ T-1: Type of fiber-optic telephone line ◦ Wireless: Delivers fast connection speeds Broadband is high-speed Internet access; most Internet users in the US have this type of access.

 Establishing and maintaining computer security is necessary to keep hardware, software, and data safe from harm or destruction.  Passwords are the most common form of restricting access to data.  Other security measures include: ◦ Electronic identification cards ◦ Firewalls to protect companies’ networks from external networks ◦ Antivirus software ◦ A proxy server that acts as an intermediary between a user and the Internet

 Wireless Security:  Wireless networking is very common, but has many security issues and hackers have found it very easy to access wireless networks.

 A server is a central computer in a network that hold collection of data (databases) and programs for connecting PCs, workstations, and other devices, which are called clients.

 Client/server network describes a software architectural model relationship.  In most cases, the client is a software program such as Mozilla Firefox. The server is hardware and can be one of many types of servers, such as a mail server, a database server, an FTP server, an application server, or a Web server.

 File server ◦ Stores remote programs and data files that are shared by a set of designated users  Database server ◦ Stores databases and database management systems  Web server ◦ Delivers web pages to browsers tan other files to applications via the HTTP protocol

 Servers enable many users to share equipment, programs, and data.  Used by small to medium-size companies and can support a few users or hundreds of users.  Most servers are referred to as network servers

 A network and server.  The benefits of a network.  The risks of network computing.  Describe the roles of clients and servers on a network.  Types of networks.  Communications media and hardware.  Network security.