NETWORK PROTOCOL:

NETWORK PROTOCOL:

Internet Protocol Suite

Protocols are the sets of rules by which communication over a network is achieved. Protocols are responsible for enabling and controlling network communication: They set the rules for the representation of data, the signals used in communications (e.g., signals regarding how the connection will be established or how information is exchanged), the detection of errors, and the authentication of computing devices on the network.
In order for different computers to communicate with each other they must both speak the same language. The rules for these languages are called Network Protocols. A protocol describes how a packet of information is organized and the rules it follows when traveling across the network.

Types of Protocol

1. TCP/IP (Transmission Control Protocol/Internet Protocol)

TCP/IP is the basic communication language or protocol of the Internet. It can also be used as a communications protocol in a private network (either an intranet or an extranet). When you are set up with direct access to the Internet, your computer is provided with a copy of the TCP/IP program just as every other computer that you may send messages to or get information from also has a copy of TCP/IP.
TCP/IP is a two-layer program. The higher layer, TCP, manages the assembling of a message or file into smaller packets that are transmitted over the Internet and received by a TCP layer that reassembles the packets into the original message. The lower layer, IP, handles the address part of each packet so that it gets to the right destination. Each gateway computer on the network checks this address to see where to forward the message. Even though some packets from the same message are routed differently than others, they'll be reassembled at the destination.
TCP/IP uses the client/server model of communication in which a computer user (a client) requests and is provided a service (such as sending a Web page) by another computer (a server) in the network. TCP/IP communication is primarily point-to-point, meaning each communication is from one point (or host computer) in the network to another point or host computer.

2. HTTP(Hypertext Transfer Protocol)

HTTP is the set of rules for transferring files (text, graphic images, sound, video, and other multimedia files) on the World Wide Web. As soon as a Web user opens their Web browser, the user is indirectly making use of HTTP. HTTP is an application protocol that runs on top of the TCP/IP suite of protocols (the foundation protocols for the Internet).
HTTP concepts include the idea that files can contain references to other files whose selection will extract additional transfer requests. HTTP daemon, a program that is designed to wait for HTTP requests and handle them when they arrive. Your Web browser is an HTTP client, sending requests to server machines. When the browser user enters file requests by either "opening" a Web file (typing in a Uniform Resource Locator or URL) or clicking on a hypertext link, the browser builds an HTTP request and sends it to the Internet Protocol address (IP address) indicated by the URL. The HTTP daemon in the destination server machine receives the request and sends back the requested file or files associated with the request.

3. FTP(File Transfer Protocol)

A FTP better known as File Transfer Protocol basically is applied to transfer data from one particular computer to another above a world-wide network.
Usually, FTP is a primarily applied protocol for exchanging data over a particular network which normally supports TCP/IP protocol. Generally there are two types of computer occupied in an FTP data transfer they are the server and the client. The FTP server, administrating server software, depends on the network for network connection request from supplementary computers. The consumer computer, which is administrating the FTP client software, starts a connection to the server. As soon as the connection is started, the client can perform numerous file manipulations like uploading them, downloading them, giving them new names, etc. Generally any software company or programming individual can create an FTP server because the protocol is open standard.

4. SMTP (Simple Mail Transfer Protocol)

SMTP is a delivery protocol only. It cannot pull messages from a remote server on demand. Other protocols, such as the Post Office Protocol (POP) and the Internet Message Access Protocol (IMAP) are specifically designed for retrieving messages and managing mail boxes. However, SMTP has a feature to initiate mail queue processing on a remote server so that the requesting system may receive any messages destined for it. POP and IMAP are preferred protocols when a user's personal computer is only intermittently powered up, or Internet connectivity is only transient and hosts cannot receive message during off-line periods.

5. TELNET

Telnet is a user command and an underlying TCP/IP protocol for accessing remote computers. Through Telnet, an administrator or another user can access someone else's computer remotely. On the Web, HTTP and FTP protocols allow you to request specific files from remote computers, but not to actually be logged on as a user of that computer. With Telnet, you log on as a regular user with whatever privileges you may have been granted to the specific application and data on that computer.
The result of this request would be an invitation to log on with a userid and a prompt for a password. If accepted, you would be logged on like any user who used this computer every day.Telnet is most likely to be used by program developers and anyone who has a need to use specific applications or data located at a particular host computer.

E-MAIL

E-MAIL

E-mail (electronic mail) is the exchange of computer-stored messages by telecommunication. E-mail messages are usually encoded in ASCII text. However, you can also send non-text files, such as graphic images and sound files, as attachments sent in binary streams. E-mail was one of the first uses of the Internet and is still the most popular use. A large percentage of the total traffic over the Internet is e-mail. E-mail can also be exchanged between online service provider users and in networks other than the Internet, both public and private.

E-mail can be distributed to lists of people as well as to individuals. A shared distribution list can be managed by using an e-mail reflector. Some mailing lists allow you to subscribe by sending a request to the mailing list administrator. A mailing list that is administered automatically is called a list server.

E-mail is one of the protocols included with the Transport Control Protocol/Internet Protocol (TCP/IP) suite of protocols. A popular protocol for sending e-mail is Simple Mail Transfer Protocol and a popular protocol for receiving it is POP3. Both Netscape and Microsoft include an e-mail utility with their Web browsers.

Advantages of Email

The benefits of e-mail are huge in number.

• Easy to use: E-mail frees us from the tedious task of managing data of daily use. It helps us to manage our contacts, send mails quickly, maintain our mail history, store the required information, etc.
• Speed: The e-mail is delivered instantly, anywhere across the globe. No other service matches the e-mail in terms of speed.
• Easy to prioritize: Since the mails have subject lines, it is easy to prioritize them and ignore unwanted mails.
• Reliable and secure: Constant efforts are being taken to improve the security in electronic mails. Thus making it one of the secured ways of communication.
• Informal and conversational: The language used in e-mails is generally simple and thus makes the communication informal. Sending and receiving e-mails takes less time, so it can be used as a tool for interaction.
• Easier for reference: When one needs to reply to a mail, there is a provision in the mailing system to attach the previous mails as references. This refreshes the recipient's knowledge, on what he is reading.
• Automated e-mails: It is possible to send automated e-mails using special programs like the autoresponders. The autoresponders reply back to the sender with generalized pre-written text messages.
• Environment friendly: Postal mails use paper as a medium to send letters. Electronic mail thus, saves a lot of trees from being axed. It also saves fuel needed in transportation.
• Use of graphics: Colorful greeting cards and interesting pictures can be sent through e-mails. This adds value to the e-mail service.
• Advertising tool: Many individuals and companies are using e-mails to advertise their products, services, etc.

Disadvantages of Email

The e-mails, though beneficial in our day-to-day life, has got its own drawbacks that are off late coming to the fore.

• Viruses: These are computer programs having the potential to harm a computer system. These programs copy themselves and further infect the computer. The recipient needs to scan the mails, as viruses are transmitted through them and have the potential to harm computer systems.
• Spam: E-mails when used to send unsolicited messages and unwanted advertisements create nuisance and is termed as Spam. Checking and deleting these unwanted mails can unnecessarily consume a lot of time, and it has become necessary to block or filter the unwanted e-mails by means of spam filters. Spamming includes, sending hoax e-mails. E-mail spoofing is another common practice, used for spamming. Spoofing involves deceiving the recipient by altering the e-mail headers or the addresses from which the mail is sent.
• Hacking: The act of breaking into computer security is termed as hacking. After the e-mail is sent and before it is received by the desired recipient, it "bounces" between servers located in different parts of the world. Hence, the e-mail can be hacked by a professional hacker.
• Misinterpretation: One has to be careful while posting any kind of content through an e-mail. If typed in a hurry, the matter could be misinterpreted.
• Lengthy mails: If the mail is too long and not properly presented the reader may lose interest in reading it.
• Not suitable for business: Since the content posted via e-mails is considered informal, there is a chance of business documents going unnoticed. Thus, urgent transactions and especially those requiring signatures are not managed through e-mails.
• Crowded inbox: Over a period of time, the e-mail inbox may get crowded with mails. It becomes difficult for the user to manage such a huge chunk of mails.

SEARCH ENGINES

SEARCH ENGINES

A web search engine is designed to search for information on the World Wide Web and FTP servers. The search results are generally presented in a list of results and are often called hits. The information may consist of web pages, images, information and other types of files. Some search engines also mine data available in databases or open directories. Unlike web directories, which are maintained by human editors, search engines operate algorithmically or are a mixture of algorithmic and human input.

List of Search Engines

1. Google (http://www.google.com)

Voted four times Most Outstanding Search Engine by Search Engine Watch readers, Google has a well-deserved reputation as the top choice for those searching the web. The crawler-based service provides both comprehensive coverage of the web along with great relevancy. It's highly recommended as a first stop in your hunt for whatever you are looking for.

2. Yahoo (http://www.yahoo.com)

Launched in 1994, Yahoo is the web's oldest "directory," a place where human editors organize web sites into categories. However, in October 2002, Yahoo made a giant shift to crawler-based listings for its main results. These came from Google until February 2004. Now, Yahoo uses its own search technology

3. Ask (http://www.ask.com)

Ask Jeeves initially gained fame in 1998 and 1999 as being the "natural language" search engine that let you search by asking questions and responded with what seemed to be the right answer to everything.

4. AltaVista (http://www.altavista.com)

AltaVista opened in December 1995 and for several years was the "Google" of its day, in terms of providing relevant results and having a loyal group of users that loved the service. Sadly, an attempt to turn AltaVista into a portal site in 1998 saw the company lose track of the importance of search. Today, AltaVista is once again focused on search. Results come from Yahoo, and tabs above the search box let you go beyond web search to find images, MP3/Audio, Video, human category listings and news results.

5. Live Search (http://www.live.com/)

Live Search (formerly Windows Live Search) is the name of Microsoft's web search engine, successor to MSN Search, designed to compete with the industry leaders Google and Yahoo. The search engine offers some innovative features, such as the ability to view additional search results on the same web page (instead of needing to click through to subsequent search result pages) and the ability to adjust the amount of information displayed for each search-result (i.e. just the title, a short summary, or a longer summary). It also allows the user to save searches and see them updated automatically on Live.com. Now a days this name is changed int BING.COM

FEW TERM OF INTERNET

FEW TERM OF INTERNET

IP Address ( Internet Protocol Address)

An IP Address is a usually numerical label assigned to each device (e.g., computer, printer) participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: network interface identification and location addressing.
In order for you to receive snail mail at home the sending party must have your correct mailing address (IP address) in your town (network) or you do not receive letter. The same is true for all equipment on the internet. Without this specific address, information cannot be received.

Domain Name System (DNS):

DNS implements a distributed database to store this name and address information for all public hosts on the Internet. DNS allows the IP address to be translated to words. It is much easier for us to remember a word than a series of numbers. The same is true for email addresses.
For example, it is much easier for you to remember a web address name such as mystudyroom.com.np  than it is to remember 192.168.1.1 or in the case of email it is much easier to remember email@gmail.com than email@192.168.1.1

Client-Server Architecture

A network architecture in which each computer or process on the network is either a client or a server. Servers are powerful computers or processes dedicated to managing disk drives (file servers), printers (print servers), or network traffic (network servers). Clients are PCs or workstations on which users run applications. Clients rely on servers for resources, such as files, devices, and even processing power.
The Internet revolves around the client-server architecture. Your computer runs software called the client and it interacts with software known as the server located at a remote computer. The client is uses a browser such as Internet Explorer or Mozilla. User type web address to open a site like mystudyroom.com.np, user's request is sent to the website's server and then users are able to view the website. This is how client and server work together.

World Wide Web (WWW)

WWW is collection of internet resources (such as FTP, telnet, Usenet), hyperlinked text, audio, and video files, and remote sites that can be accessed and searched by browsers based on standards such as HTTP and TCP/IP. Also called the web as an easier way to access information scattered across the internet.
The WWW is a spiderweb-like interconnection of millions of pieces of information located on computers around the world. Web documents use hypertext, which incorporates text and graphical links to other documents and files on Internet-connected computers.

Static and Dynamic Pages

Web pages can be either static or dynamic. "Static" means unchanged or constant, while "dynamic" means changing or lively. Therefore, static Web pages contain the same prebuilt content each time the page is loaded, while the content of dynamic Web pages can be generated on-the-fly.
Standard HTML pages are static Web pages. They contain HTML code, which defines the structure and content of the Web page. Each time an HTML page is loaded, it looks the same. The only way the content of an HTML page will change is if the Web developer updates and publishes the file.
Other types of Web pages, such as PHP, ASP, and JSP pages are dynamic Web pages. These pages contain "server-side" code, which allows the server to generate unique content each time the page is loaded. For example, the server may display the current time and date on the Web page. It may also output a unique response based on a Web form the user filled out. Many dynamic pages use server-side code to access database information, which enables the page's content to be generated from information stored in the database. Websites that generate Web pages from database information are often called database-driven websites.
You can often tell if a page is static or dynamic simply by looking at the page's file extension in the URL, located in the address field of the Web browser. If it is ".htm" or ".html," the page is probably static. If the extension is ".php," ".asp," or ".jsp," the page is most likely dynamic. While not all dynamic Web pages contain dynamic content, most have at least some content that is generated on-the-fly.

Advantages of static websites

• Quick to develop website
• Cheap to develop and host website

Disadvantages of static websites

• Requires web development expertise to update site
• Site not as useful for the user
• Content can get stagnant

Advantages of dynamic websites

• Much more functional website
• Much easier to update
• New content brings people back to the site and helps in the search engines
• Can work as a system to allow staff or users to collaborate

Disadvantages of dynamic websites

• Slower / more expensive to develop
• Hosting costs a little more

TYPE OF TRANSMISSION

TYPE OF TRANSMISSION

Analog and Digital Transmission

Analog Transmission

Analog transmission uses signals that are exact replicas of a sound wave or picture being transmitted. Signals of varying frequency or amplitude are added to carrier waves with a given frequency of electromagnetic current to produce a continuous electric wave. The term "analog signal" came about because the variations in the carrier waves are similar, or analogous, to that of the voice itself.
For example, in analog transmission, say a telephone system, an electric current or the reproduction of patterned sound waves are transmitted through a wire and into the telephone receiver. Once this is completed, they are then converted back into sound waves.

Digital Transmission

In digital transmission the signals are converted into a binary code, which consists of two elements-positive and non-positive. Morse code and the "on and off" flashing of a light are basic examples. Positive is expressed as the number 1, while non-positive is expressed as the number 0. Numbers that are expressed as a string of 0s and 1s are called binary numbers. Every digit in a binary number is referred to as a bit .
As an example of digital transmission, in a type of digital telephone system, coded light signals produced by a rapidly flashing laser travels through optical fibers (thin strands of glass) and are then decoded by the receiver. When transmitting a telephone conversation, the light flashes on and off about 450 million times per second. This high rate enables two optical fibers to carry about 15,000 conversations simultaneously.

E-MAIL

E-MAIL

E-mail (electronic mail) is the exchange of computer-stored messages by telecommunication. E-mail messages are usually encoded in ASCII text. However, you can also send non-text files, such as graphic images and sound files, as attachments sent in binary streams. E-mail was one of the first uses of the Internet and is still the most popular use. A large percentage of the total traffic over the Internet is e-mail. E-mail can also be exchanged between online service provider users and in networks other than the Internet, both public and private.
E-mail can be distributed to lists of people as well as to individuals. A shared distribution list can be managed by using an e-mail reflector. Some mailing lists allow you to subscribe by sending a request to the mailing list administrator. A mailing list that is administered automatically is called a list server.
E-mail is one of the protocols included with the Transport Control Protocol/Internet Protocol (TCP/IP) suite of protocols. A popular protocol for sending e-mail is Simple Mail Transfer Protocol and a popular protocol for receiving it is POP3. Both Netscape and Microsoft include an e-mail utility with their Web browsers.

Advantages of Email

The benefits of e-mail are huge in number.

• Easy to use: E-mail frees us from the tedious task of managing data of daily use. It helps us to manage our contacts, send mails quickly, maintain our mail history, store the required information, etc.
• Speed: The e-mail is delivered instantly, anywhere across the globe. No other service matches the e-mail in terms of speed.
• Easy to prioritize: Since the mails have subject lines, it is easy to prioritize them and ignore unwanted mails.
• Reliable and secure: Constant efforts are being taken to improve the security in electronic mails. Thus making it one of the secured ways of communication.
• Informal and conversational: The language used in e-mails is generally simple and thus makes the communication informal. Sending and receiving e-mails takes less time, so it can be used as a tool for interaction.
• Easier for reference: When one needs to reply to a mail, there is a provision in the mailing system to attach the previous mails as references. This refreshes the recipient's knowledge, on what he is reading.
• Automated e-mails: It is possible to send automated e-mails using special programs like the autoresponders. The autoresponders reply back to the sender with generalized pre-written text messages.
• Environment friendly: Postal mails use paper as a medium to send letters. Electronic mail thus, saves a lot of trees from being axed. It also saves fuel needed in transportation.
• Use of graphics: Colorful greeting cards and interesting pictures can be sent through e-mails. This adds value to the e-mail service.
• Advertising tool: Many individuals and companies are using e-mails to advertise their products, services, etc.

Disadvantages of Email

The e-mails, though beneficial in our day-to-day life, has got its own drawbacks that are off late coming to the fore.

• Viruses: These are computer programs having the potential to harm a computer system. These programs copy themselves and further infect the computer. The recipient needs to scan the mails, as viruses are transmitted through them and have the potential to harm computer systems.
• Spam: E-mails when used to send unsolicited messages and unwanted advertisements create nuisance and is termed as Spam. Checking and deleting these unwanted mails can unnecessarily consume a lot of time, and it has become necessary to block or filter the unwanted e-mails by means of spam filters. Spamming includes, sending hoax e-mails. E-mail spoofing is another common practice, used for spamming. Spoofing involves deceiving the recipient by altering the e-mail headers or the addresses from which the mail is sent.
• Hacking: The act of breaking into computer security is termed as hacking. After the e-mail is sent and before it is received by the desired recipient, it "bounces" between servers located in different parts of the world. Hence, the e-mail can be hacked by a professional hacker.
• Misinterpretation: One has to be careful while posting any kind of content through an e-mail. If typed in a hurry, the matter could be misinterpreted.
• Lengthy mails: If the mail is too long and not properly presented the reader may lose interest in reading it.
• Not suitable for business: Since the content posted via e-mails is considered informal, there is a chance of business documents going unnoticed. Thus, urgent transactions and especially those requiring signatures are not managed through e-mails.
• Crowded inbox: Over a period of time, the e-mail inbox may get crowded with mails. It becomes difficult for the user to manage such a huge chunk of mails.

Need to check the inbox regularly: In order to be updated, one has to check his e-mail account regularly.