1. Networks: LANs, WANs and Communication Protocols How do computers communicate?

2. Resource sharing Printers Files Email

3. Communication Protocols Non-routed (similar to a home phonethat everyone in the house shares – good for a few people) –Example: Netbui Routed (similar to an operator-directed phone system-good for a large company) –Example: TCP/IP

4. Routers A routed protocol such as TCP/IP uses “routers” (similar to the operators in the phone system) to direct information.

5. Local Area Network (LAN) Uses one protocol and is usually in a small (local) area. Diagram:

6. Wide Area network (WAN) and Gateways A WAN is a group of LANs loosely connected via gateways. A Gateway helps to translate and allow communication across LANs that have different protocols. Diagram:

8. ARPA-NET Funded by the Dept. of Defense Goal was to develop a robust distributed network with no central place. Concerned about a nuclear attack from the Soviet Union Slowly developed into the Internet

9. Client/Server Model Client: The Software program that requests the use of a shared resource Server: The software program that allows the use and sends the requested resource

10. IP Address The machine “name” required by TCP/IP protocol for every computer on the network. Four groups of number separated by a period. Used by routers just as an address is used by the postal (snail) mail carrier.

11. Domain Name An English-like machine name that is easier to remember than an IP address There are look-up tables to match IP addresses to Domain Names.

12. Domain Name Server (DNS) A server program that provides the correct IP address for a Domain Name. The client browser may go through two steps a.Request the proper IP address from the Domain Name Server (DNS) located at your ISP. b.Request the web page from the web server located at the requested IP address.

13. Uniform Resource Locator (URL) Specifies the exact location of a resource. Three parts: protocol service, machine name and resource –http://acc6.its.brooklyn.cuny.edu/~cc312/lab1.htmhttp://acc6.its.brooklyn.cuny.edu/~cc312/lab1.htm –ftp://www.sci.brooklyn.cuny.eduftp://www.sci.brooklyn.cuny.edu –C:\resources\printer1 l