1. Networking BASICS1 Wide Area Networks

2. Networking BASICS2 Wide Area Network It connects computers and LANs over a larger geographical area. It crosses public thorough-fares such as roads, railroads, and water.

3. Networking BASICS3 WAN vs. LAN Geography Ownership Management Speed Cost

4. Networking BASICS4 Wired Analog Service It uses standard wired analog telephone lines. It requires a modem to convert digital signals to analog signals. Its top is speed 56 Kbps. Asymmetric – Some modems are faster downloading than uploading.

5. Networking BASICS5 Wired Analog Service

6. Networking BASICS6 Digital Cellular It provides WAN data access to mobile users. Its coverage area is divided into smaller cells. Users “roam” into adjacent cells or “handoff” into remote networks. The current technology is 2.5G with a maximum speed of 384 Kbps.

7. Networking BASICS7 Trunk-Based Leased Lines The same type of lines are used to connect the telephone company’s switches. They provide “always-on” high-speed connections. The most common is T1, which oper-ates at 1.5 Mbps over twisted pair wires.

8. Networking BASICS8 Trunk-Based Leased Lines

9. Networking BASICS9 Digital Subscriber Lines (DSL) They transmit at 1.5 Mbps over regular telephone lines. They use the higher unused frequencies to send data. Different versions of DSL: ADSL, G.list, HDSL, HDSL2

10. Networking BASICS10 Digital Subscriber Lines (DSL)

11. Networking BASICS11 Cable Modem It uses the same coaxial cable that brings in cable TV signals. All cables for a neighborhood are connected to a neighborhood splitter. The connection is shared among all users in a neighborhood. Speed: 300 Kbps – 1.5 Mbps

12. Networking BASICS12 Local Multipoint Distribution Service (LMDS) Transmits: Maximum 155 Mbps downstream and 1.54 upstream Range: 2 – 5 miles It is a low-cost option to laying fiber optic cables. Its signals are susceptible to interference from rain or fog.

13. Networking BASICS13 Multichannel Multipoint Distribution Service (MMDS) It uses lower-frequency signals than LMDS. Range: up to 35 miles Its signals are less susceptible to interference from rain or fog.

14. Networking BASICS14 Satellites They have been used for over 40 years. They relay signals from one point on earth to another. They are classified according to the type of orbit.

15. Networking BASICS15 Low Earth Orbiting (LEO) They orbit at an altitude of 200 – 900 miles. They circle the earth in 90 minutes. They have a small “footprint.” More satellites are needed to cover the entire earth.

16. Networking BASICS16 Low Earth Orbiting (LEO)

17. Networking BASICS17 Medium Earth Orbiting (MEO) They orbit at altitudes between 1,500 – 10,000 miles. They circle the earth every 12 hours. They have a large “footprint.” Fewer are needed to cover the earth.

18. Networking BASICS18 Remote Wireless Bridge It connects LANs located in different buildings. The distance between buildings can be up to 18 miles at 11 Mbps. It has similar characteristics to a wireless LAN.

19. Networking BASICS19 Free Space Optics (FSO) It transmits up to 1.25 Gbps at a distance of 2.5 miles. It uses low-powered infrared beams. Its transmissions cannot be eavesdropped.

20. Networking BASICS20 Virtual Private Network (VPN) It uses the public Internet to transmit private data. It encrypts data into a packet before sending. There is no cost for setting up or using a VPN.

21. Networking BASICS21 Virtual Private Network (VPN)

22. Networking BASICS22 Public Switched Data Networks (PSDN) Actual network itself X.25 Frame Relay Asynchronous Transfer Mode (ATM)

23. Networking BASICS23 Public Switched Data Networks (PSDN) Integrated Services Digital Network (ISDN) Synchronous Optical Network (SONET) Metro Ethernet Network (MEN)

24. Networking BASICS24 Firewall It inspects incoming traffic. Packet-filter firewall – Inspects header of each packet. Stateful packet-filter firewall – Examines a packet’s source IP. Proxy firewall – Examines the contents of a packet.

25. Networking BASICS25 Network Address Translators (NAT) Disguises the internal IP by substituting a fake IP and port number. When a packet is returned, NAT replaces the fake numbers with the actual IP and port number.

26. Networking BASICS26 Privacy Privacy is the right to be left alone to the degree that you choose. It is a difficult problem to keep personal data private. Identity theft is a major crime.

27. Networking BASICS27 Networking BASICS The Internet and Its Tools

28. Networking BASICS28 The Internet It is not controlled or managed by one person or group. Anyone can connect to the Internet. There is no control regarding what can be posted.

29. Networking BASICS29 History The U.S. was concerned that foreign nations may attack. A computer network was needed that could withstand an attack. The Internet was modeled after the interstate highway system.

30. Networking BASICS30 History ARPANET was launched in 1969 to link 4 sites. TCP/IP allowed multiple computers to connect to each other. It was replaced by NSFNET in the 1980s. Hypertext Transport Protocol and browsers opened up the Internet to anyone.

31. Networking BASICS31 Domain Name System (DNS) It resolves (or finds) a Web site’s IP number when given its name. It is a database organized as a hierarchy. It is organized into 3 different levels. DNS is distributed at multiple locations.

32. Networking BASICS32 Domain Name System (DNS)

33. Networking BASICS33 Web Browsers They allow users to view text, data, pictures, animation, and video. A Web page contains instructions to a browser about how to display items. Microsoft Internet Explorer is the most popular browser.

34. Networking BASICS34 E-Mail It is the most common Internet tool. They are either character-based or use a graphical user interface. Documents are sent as attachments. File compression software reduces the size of attachments.

35. Networking BASICS35 Listserv It is also called a discussion list. It is an extension of an e-mail distribution list. Users subscribe and automatically receive copies of all e-mail messages. Listserv address – Address of the automated mailing program.

36. Networking BASICS36 Listserv Etiquette Spend time reading before responding. Use a descriptive Subject heading. Include part of the original message when replying. Use upper- and lowercase.

37. Networking BASICS37 Newsgroup Questions and answers are posted in a central location. It is not necessary to save or sort e- mail messages. It may require special software of the client.

38. Networking BASICS38 Newsgroup

39. Networking BASICS39 Portals Portals are also known as an online service. Portals are ready-made menus of lists of information. Each selection narrows choices until the information is located.

40. Networking BASICS40 Search Engine The spider reads the Web pages and stores information in an index. The search engine sifts through the index to find the user’s requests. The ranking of pages is important.

41. Networking BASICS41 Search Engine

42. Networking BASICS42 Hypertext Markup Language (HTML) It is the standard way of defining how text and graphics are displayed. The browser reads HTML document instructions.

43. Networking BASICS43 Hypertext Markup Language (HTML) Each page is made up of elements. The elements are indicated by tags. A tag is. The ending tag contains a slash....