Lecture About Internet

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Class 8th Metric and O-Level Notes about Internet Servers BY Qasim Suleman 2nd Lecture: 22-02-2008

Server:

A computer system in a network that is shared by multiple users. Servers come in all sizes from x86-based PCs to IBM mainframes. A server may have a keyboard, monitor and mouse directly attached, or one keyboard, monitor and mouse may connect to any number of servers via a switch (see KVM switch). In large companies, servers often reside in racks in the data center, and all access is via their network connections. See server farm and rack mounted. In information technology, a server is a computer system that provides services to other computing systems—called clients—over a computer network. The term server can refer to hardware (such as a Sun computer system) or software (such as an RDBMS server).

Internet Servers: The Internet is made up of client computers, servers, cables and network connection devices. Almost the entire structure of the Internet is based upon a client-server model. Many millions of servers are connected to the Internet and run continuously throughout the world. Among the many services provided by Internet servers are: the Web; the Domain Name System; electronic mail; file transfer; instant messaging; streaming audio and video, online gaming, and countless others. Virtually every action taken by an ordinary Internet user requires one or more interactions with one or more servers. Web Servers: Web Servers are foundation of the Internet. The Web Pages are stored in Web servers. Whenever you open up your browser and type in a Web site address, it is the server that gets you the page you request. Mail Servers: Mail Servers are as crucial as Web servers. They move and store mails over private networks and across the Internet. FTP (File Transfer Protocol) Servers: FTP servers store text files, graphic files, sound files. Etc and let the client download and upload them. Database Servers: Database Servers are specifically configured to run database software. A database is a collection of data that is organized so that its contents can easily be accessed, managed. And updated. Content Management Servers: Content management servers enable the process of creating, editing, storing, organizing, and publishing content on the web.

2 Real- Time Communication Servers: Chat, and IRC servers enable a large number of users to exchange information in an environment similar to an Internet newsgroup but with real time discussion capabilities. Instant messaging servers, like chat servers, facilitate communication in real time. However, instant messaging generally involves one conversation between two people. DNS (Domain Name Server) DNS matches up the URL of a Web site (eg www.pakturkisb.edu.pk) with its proper numeric IP address. It translates www.pakturkisb.edu.pk into the unique numeric IP address 212.175.211.243. Whenever you request a Webpage the Web browser must consult the domain name server to find out what the numeric translation of the URL is. This is necessary because computers only understand IP address, whereas people prefer to use meaningful and more memorable text. Extra Information: Domain name: name that identifies one or more IP addresses. For example, the domain name microsoft.com represents about a dozen IP addresses. Domain names are used in URLs to identify particular Web pages. For example, in the URL http://www.pakturkisb.edu.pk, the domain name is pakturkisb.edu.pk. Every domain name has a suffix that indicates which top level domain (TLD) it belongs to. There are only a limited number of such domains. For example:

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gov - Government agencies pk

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edu - Educational institutions

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org - Organizations (nonprofit) mil - Military com - commercial business net - Network organizations ca - Canada th - Thailand

Because the Internet is based on IP addresses, not domain names, every Web server requires a Domain Name System (DNS) server to translate domain names into IP addresses. DNS: 1) Short for Domain Name System (or Service or Server), an Internet service that translates domain names into IP addresses. Because domain names are alphabetic, they're easier to remember. The Internet however, is really based on IP addresses. Every time you use a domain name, therefore, a DNS service must translate the name into the corresponding IP address. For example, the domain name www.example.com might translate to 198.105.232.4.

3 The DNS system is, in fact, its own network. If one DNS server doesn't know how to translate a particular domain name, it asks another one, and so on, until the correct IP address is returned. (2) Short for digital nervous system, a term coined by Bill Gates to describe a network of personal computers that make it easier to obtain and understand information.