1. Understanding Networks Computer Technology

2. What is a Network?  Two or more computers connected to each other so they can—  Exchange Information  E-mail messages  Documents  Share Resources  Disk storage  Printers  Share Applications  First computer network invented when ancient mathematicians connected their abacuses together with string so they could instantly share their answers

3. Types of Network Connections  Electrical cables carry information in the form of electrical signals  Fiber-optic cables enable computers to communicate at extremely high speeds by using impulses of light  Wireless networks enable computers to communicate by using radio signals

4. Terminology

5. Network Terms  File Server  A computer connected to a network that distributes resources to other users.  Contains the software to manage and process files for other network users.  Host Computer  Refers to any computer that provides services to network users.  Used more commonly with the Internet.

6. Network Terms (continued)  Workstation  Refers to a personal computer connected to a network.  Example: Each computer in the classroom.  Client  Refers to the software on a computer that allows the user to access the server.  Example: Novell Netware

7. Network Connection Devices  Modem  A device that sends and receives data to and from computers over telephone lines.  Hubs  A device that connects several components of a network.  Routers  A device that connects at least two networks.  Gateway  A device that serves as an entrance to another network.  All of these can be used alone or combination.

8. Network Components

9. Client Computers  Used to access network resources  Usually found on a user’s desktop  Often called workstations

10. Server Computers  Provide  Shared resources  Disk storage  Printers  Network services  E-mail  Internet access  Run a specialized network operating system  Windows 2000  Netware  Linux

11. Network Interface Cards (NICS)  Small circuit board that converts the digital signals from a computer into signals that can travel over a network.  Enables the computer to communicate over a network.  Most NICS use a networking standard called Ethernet.  Every client and every server must have a NIC.  Desktop Computers have the NIC inside the case with a jack on the outside for the network cable.  Notebook or Laptop Computers have a special card that fits into a slot or opening in the case.

12. Cables  Physically connect computers together to form a network  Types  Twisted pair (10BaseT)  Coaxial (10Base2)  Fiber-optic (high-speed connections)

13. Hubs and Switches  Hub  Common connection point for devices in a network  Doesn’t know anything about the computers connected to its ports, so it sends packets to every computer  Switch  Used to network multiple computers together.  Two Types  Low-end switches are typically small, flat boxes with 4 to 8 Ethernet ports.  High-end switches can have more than 50 ports and often are rack mounted.  Knows which computer is connected to each of its ports, so it only sends packet to the correct port

14. Wireless Network  Enables computers to communicate through radio signals  Radio transmitters and receivers take the place of cables  Advantages: More flexibility than cabled network  Disadvantages: Less secure than cabled network

15. Network Types

16. Local Area Network (LAN)  Network located within a limited geographical area, such as a school or small business  Each computer or printer on the network is called a “node”  Geographic distance, not number of computers indicates it is a LAN

17. Wide Area Network (WAN)  Network that spans a large geographic territory  Connect two or more LANs that are relatively far apart  Geographic distance, not number of computers indicates it is a WAN

18. Network Topology  Shape of how the computers and other network components connect to each other  Terms  Node  Device that is connected to the network  Same as a computer  Packet  Message sent over the network from one node to another node  Includes the address of the node that sent the packet, address of the node the packet is going to, and the data.

19. Network Topology Types Bus Topology  Nodes are strung together in a line  Commonly used for LANs

20. Network Topology Types Star Topology  Each network node connects to a central device called a hub or a switch  Commonly used for LANs  If the hub fails, all computers on the network are disconnected

21. Network Topology Types Ring Topology  Each network computer and device are connected to each other to form a large circle  Each packet is sent around the circle from computer to computer until it reaches its destination

22. Network Topology Types Mesh Topology  Multiple connections between each of the nodes on the network  Network can use an alternative route to deliver a packet if one cable breaks

23. IP Address  A unique identifying number assigned to each computer connected to the internet.  Example – 204.127.102.001  Each computer on a network should have its own separate IP Address or conflicts will occur when there are duplicate addresses.

24. Internet

25. What is the Internet?  Global network connecting millions of computers  Each internet computer, called a host, is independent  Not synonymous with World Wide Web (www)  Requires  Internet Service Provider (ISP) or Online Service Provider (OSP)  Browser  Search Engine

26. Internet Terms  Internet Service Provider (ISP)  Company that provides access to the Internet so you can  Browse the web  Send and receive e-mail  Requires you to  Pay a monthly fee, in exchange for Software package Username Password  Have a modem  Browser  Software application used to locate and display web pages  Search Engine  Searches documents for specified keywords  Returns a list of the documents that contain the keywords

27. Internet Terms  HTTP (Hypertext Transfer Protocol)  Language used to transfer data within the World Wide Web  URL (Uniform Resource Locator)  Method used to identify locations on the Internet  Format: http://server-name.pathhttp://server-name.path  Example: http://www.microsoft.comhttp://www.microsoft.com  Domain  Last part of the URL  Identifies the server type.com indicates a commercial company.edu indicates educational.gov indicates government.mil indicates military

28. Internet Terms  Freeware  Copyrighted software the author usually gives away for free  Author retains the copyright, which means  You cannot do anything with it that the author hasn’t authorized  You can use the software, but not sell it  Shareware  Software distributed on the basis of an honor system  Usually free, but in most cases, the author asks you to pay a small fee if you like it and use it on a regular basis  You can copy shareware and give it to your friends and colleagues, but they need to pay a fee if they use the product

29. Internet Terms  Public Domain  Refers to any program that is not copyrighted  Software that is free and can be used without restrictions  Spam  Electronic junk mail or junk newsgroup postings

30. Internet Terms  Boolean Operator  Used to narrow or broaden you search  Helps eliminate unrelated documents  Most common terms  AND Narrows a search by combining terms Retrieves documents that use both the terms you specify  Example: Portland AND Oregon  OR Broadens a search to include results that contain either of the words you enter  Example: Liberal OR Democrat  NOT Narrows a search by excluding search terms Retrieves documents that contain one, not both terms  Example: Oregon NOT Travel

31. Internet Terms  Trolling  To deliberately post derogatory or inflammatory comments to a community forum, chat room, newsgroup, or blog in order to bait other users into responding.  To surf the Internet