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Class 7 -- Topics • • • • • • • Midterm next week (Don’t’ forget!) A history of the Internet The physical Internet The ‘virtual’ Internet The World Wide Web (WWW) Navigating the WWW HTTP/ISP/FTP/M-O-U-S-E MA194 Using WindowsNT 1 Regional Networks We know that a local area network (LAN) is something we see in office buildings, college campuses and large organizations. A wide area network (WAN) is often a larger network that just ties these smaller ones together. Thus, regional networks covered large areas of the country like the west coast, the New York area and the Southeastern part of the United States. MA194 Using WindowsNT 2 The Internet - A history NYSER A UCB C SURA B MA194 Using WindowsNT 3 Identifying specific machines Machine “A” at UCB A A.UCB.EDU UCB B.SURA.EDU Machine “B” at SURA C Machine “C” at SURA SURA B C.SURA.EDU MA194 Using WindowsNT 4 Identifying specific machines A.UCB.EDU A UCB C C.SURA.EDU SURA B B.SURA.EDU MA194 Using WindowsNT 5 Identifying specific machines A.UCB.EDU A NYSER UCB B B.NYSER.COM C C.SURA.EDU SURA B B.SURA.EDU MA194 Using WindowsNT 6 Too many names! To prevent one site (say, NYSER.COM) from having the same name as a machine at another site (UCB.EDU), the domain is added to the machine name to give us the Fully Qualified Domain Name (FQDN). MA194 Using WindowsNT 7 Many names, one machine At times, it is useful to have more than one name associated with a given machine. However, we still need to uniquely identify each machine without having to know all possible names, thus there are Internet Protocol numbers (IP numbers). MA194 Using WindowsNT 8 IP Numbers An IP number is composed of 4 sets of numbers, ranging from 0 to 255, for example: 128.163.128.19 128.1.128.1 128.163.136.2 127.0.0.1 MA194 Using WindowsNT 9 Converting IP #s and names T1.mscf.uky.edu 128.163.132.101 t8.mscf.uky.edu 128.163.132.108 pigpen.ate.uky.edu 128.163.130.10 The conversion is handled by the system using a distributed database called the nameserver or nameservice. MA194 Using WindowsNT 10 ISP - Internet Service Provider An ISP is an Internet Service provider which is simply an organization (a company, school, etc.) that provides access to the Internet, usually by phone. MA194 Using WindowsNT 11 Dial Up Access to the Internet One method computers use to connect to the Internet uses an everyday phone line and a modem. One computer (the client or remote end) calls up another computer (the host or ISP end) and the two computers speak via their modems over the phone line. MA194 Using WindowsNT 12 PPP - Point to Point Protocol The ‘language’ some computers use to establish a connection to the Internet is called a protocol. A few years ago, the most common form was called SLIP for Serial Line Internet Protocol. Today, an improved form is known as PPP or Point-to-Point Protocol. MA194 Using WindowsNT 13 [email protected] An email address is composed of two parts, the user id and the domain name. The domain name may be a machine or it may reflect a domain for machines. The domain section uniquely identifies the machine to deliver the mail to whereas the user id section specifies the individual user for the mail. MA194 Using WindowsNT 14 Http://www.ms.uky.edu/~ma194 A Universal Resource Locator (URL) has three parts: The service (http://), the machine to access (www.ms.uky.edu) and the pathname of the web page (which is often the name of the user on the machine.) MA194 Using WindowsNT 15