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Introduction to Networks: Types, Applications, and Security

Learn about different types of networks, network applications, physical networking, information storage, exchange, network security, and internet fundamentals in this lecture.

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Introduction to Networks: Types, Applications, and Security

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  1. Networks CPS120 Introduction to Computer Programming Lecture 4

  2. What Is a Network • A network is a group of connected computers that allow people to share information and equipment

  3. Types of Networks • LAN (Local Area Network) connects computers within a small geographic area like a building • WAN (Wide Area Network) connects computers across a large geographic area like a city or country (often via satellite) • Internet: World-wide network of networks

  4. Advantages • Road warriors • Eliminate “sneakernet” • Share information • Share equipment

  5. Who Runs It? • A network administrator manages the network and makes sure it runs smoothly • Often called a systems administrator or an IS manager

  6. Network Applications • Electronic mail • Groupware • Calendaring • Scheduling • Video-conferencing • Requires sound card, speakers, mike & camera

  7. Physical Networking • Hubs • A hub is a device that provides a central location where all the cables on a network come together • NICs (Network Interface Card) • An expansion card that physically connects each computer to the network • Cables • Coaxial, Unshielded Twisted Pair (UTP), Shielded Twisted Pair, Fiber-optic • Wireless

  8. How Information Is Stored • Client-Server: • Used for large networks • Files are stored on a central computer and everyone who can access the network can be given access them • Easy to create scheme to backup and protect files • Client: a computer that can access information stored on the server • Server: Central computer that stores files • NetWare, UNIX, Windows NT/2000

  9. How Information Is Stored • Peer-to-Peer: • Used for a small number of computes (e.g. 10) • Files stored on own computers; access given to them to others on the network • LANtastic, Windows-98, Windows-ME

  10. How Information Is Exchanged • Ethernet: • Most popular and least expensive solution • Each computer waits for a pause before sending information • Like polite conversation • Collisions between information often occur • Computers wait a moment, then resend • Ethernet – 10 Mbps, Fast Ethernet – 100 Mbps, Gigabit Ethernet 1000 Mbps

  11. How Information Is Exchanged • Token-ring is a type of network where a token that collects and delivers information is passed from compute to computer • Speeds of 4 or 16 Mbps • Asynchronous Transfer Mode (ATM) is a type of network that works by sending information in equal-sized pieces called cells • 25, 155, 622 or 2488 Mbps • Often networks networks

  12. Network Security • Firewall – specialized hardware or software package designed to protect a private computer network from unauthorized access • Think “Moat” • User name and password • Used for authentication • Good passwords

  13. Intranet • Small version of the Internet in a company • Uses familiar web-browsers and email packages • Allows hyper-linking • VPNs (Virtual Private Network) • End-to-end encryption • More cost efficient than private lines

  14. Internet and WWW Chapter 10

  15. Internet Fundamentals • Dates from DARPA in the 1960s • Consists of thousands of connected networks around the world • Each organization on the Internet is responsible for maintaining its own equipment • These organizations allow you to pass-through their nets • Designed to provide multiple routing to bypass disabled computers • Called cyber-space or the information superhighway

  16. Internet Offerings • Electronic mail (Most popular application) • Information • Entertainment • Discussion Groups • Chat • Programs (Shareware) • Online shopping

  17. Connecting • Computer • Software • Modem or high-speed connection • ISP (Internet Service Provider) • Access for a fee

  18. World Wide Web • Part of the Internet consisting of a huge collection of documents stored on computers around the world • Web server: computer that stores and delivers web pages • Web site: collection of web pages • URL (Uniform Resource Locator) – unique address • HTTP, Computer, Directory, Name of Page • Hyperlinks jump to different web pages

  19. Browsers • A program that lets you view and navigate information on the World Wide Web • Home Page: Web page that appears each time you start your web browser • Browser: • Internet Explorer • Netscape Navigator • Features • Bookmark • History lists

  20. Multimedia • MP3 – compressed files containing music or video • WinAmp • Streaming video – requires player • RealPlayer, QuickTime • Enhancements • Java • JavaScript • ActiveX

  21. Web Portal • Central starting point for browsing personalized by the individual • Yahoo, Excite, Go, Lycos • Info • Free services like email, shopping, chat, games, stock quotes and sports scores

  22. Shopping • Auctions • Secure web sites – i.e. HTTPS

  23. Children on the Web • Inappropriate information • Pictures • Documents • Protection • Adult supervision • Browser restrictions • Restriction programs • CyberPatrol • NetNanny

  24. Create & Publish Web Pages • HyperText Mark-up Language is a computer code used to create Web pages • There are many programs available, called visual editors which can help you create Web pages without having to learn HTML • Publishing your pages – loaded to an addressable server

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