B.Sc CA Unit 4 Notes PDF

# COMPUTER FUNDAMENTALS AND INTERNET! ## Unit 4 ### Network - A network is a group of 1 or more extra comp... systems which are related through a crupli of channels for the motiure of sending and receiving records or media. - The community also consist of several gudgetes / mediums that resource...

# COMPUTER FUNDAMENTALS AND INTERNET! ## Unit 4 ### Network - A network is a group of 1 or more extra comp... systems which are related through a crupli of channels for the motiure of sending and receiving records or media. - The community also consist of several gudgetes / mediums that resource commuique among car extra machimt those gadgets are known as Network device and consists of routers, sunetches, hubs and bridges amongst others. ### Internet - Deucloper Vinton Cerf and Bob Khan is a gp of Comp. system related from all around the world. - The Internet protocol suite is a foramework lifimed through the internet standards. Methods are divided right into a layered set of protocols on this architecture. - The internet give a huge variety of stalistic and communique offerings which includes forms database email and hypertext. - It is made of the neighborhood to global personal public network connected through plenty of cligats, vineless and Networking technologies. ### History of Internet - The history of the internet has its origin in the effearts to build eind interconnect computer network that encore ferem research and clamelopment in the united states and inovolued international collaboration particularly with researchers in the united king dom and France. ### History of Computer Network - The history of modern Computer networking techonlogy goes back to 1969 when ARPNET (Advanced Research Projects Agency Network) become the fisut Connect computer Network. - It implemented He TCP/IP protocol suite which later became the internet, ARPNET was dealoped by the. Advanced Research projects Ag mey, a. subset of the us department. - The goal of ARPANET to keep lines of from open the usа. - and USSR decide to exchange nudent devices. ### Working of Internet - The two components up holds the functionality of the Internet they are: - Packets - The data which is bing transmitted through the internet is sentvia small sigments which are later translated into bils the packets get routed to their endpaint (destination)vandous networking. - Protocols - A protocol is standardizel way of doing certain actions and formatting dect a so that two or more deules are able to communicate with and understand each other, there are protocols fors sending packets between devices on those the rame Network (enthernet) for sending Rackets from Network to N/W (IP) for ensering packets successfully arrive in order (TCP) and for formatting data for webrites and applications (HTTP) In addition to these foundational protocols there are also protocols forleitto → routing testing and en erytion. ### Models of connecting to internet : - Mobile wifi Hotspots : - Cable, setillite ISDN - Dialup Broodbemd, DSL ### Mobile - Offer voice plans with Internet access mobele Internet connections provide good speeds and allow you to access the Internet. ### Wifi Hotsports - Accers over a wirless local area Network (WLANI by way of a router that then connects to aninter net serince provider It exchange data wirerraly or through sradio waves. Hotspots can be phone-based or fosi standing commercial our free to the public. ### Dialup - Require users to link their phone line to a Computer in ander to access the internet. ### Broadbands - The high speed internet connection is Provided through either cable as telephone companies. It uses multiple elata channel to send lауе quantities of information. ### DSL - Digital rubs eriber lines user existing 2- wire copper tale phone line connected to one's homes. So service is delivered at the same time as landing telephone- ### Cable - Cable internet connection is a form of boroad band elccess through use of a cable modem users can accers the internet aver cable TV lines. Cable meadem can provide extremely fart access to the enternet. ### Satellite - In certain areas where broadband connection is not yet offered a setellite internet option may be available. Similar to wireless access ratelile connection utilizes a moden. ### ISDN - Intergrated-. Serice digital Network allows users to send data vaice video content ouer digital telephone lines. The installation of an ISDN a state dapter is required et both ends of the transmission on the part of the user as well as Internet accers provider. ### ISP - ISP provides access to the internet. ISP may also provides other servier including email servies domain registration web harting and brouser packages. - An Isp may also referred to as, an information serince packages provider a storage service provider an Internet service provider (INSP), Internet use has evolved from only there, With university or government accounts having access to nearly everyone heuling access whether its paid or free. Access has gone from dial-up connection to high speed broal bond technology. ### IP Addresses - An IP addrus on the internet or any net work form another IP difins the set of commonds directing the setup of data transferred through the Internet ar any other local Network. - IP addresersare ill the identifier that allows information to be sent between devices on a network. - An IP addrus is a string of numbers. - Example 192-158-1.38. Each number in the set can range from 0-225 so the full IP adderering rangi gous from 0.0.0.0 to 285.255.255-255. ### MAC (Mobile Access Control) - A MARE address sometimes referred to as a hardwork or physical aeldrers is unique 12- 5 charecter alphanumeris attribute that is used to identify individual electronic device on a network. - Ex-06-BO-00-63-02-26. - MAC addruses are primerily & cesrigned by device peo manufactures and the refere often referred to as the burned Sin adelouses Dor as an etternet hardware addruers hard weare addrues or physical addrers. - Eachadelrers can be stared in hardware. ### DNS (Domain name system) - An application layer protocol definess threw the apptica application process runing on different systems. pass the message to each other. - DNS stands for Domain Name system. - It is a directory service that provides a mapping between the name of a hart on the network and its numerical welliers. - It is required for the function of the internet. Each node in a tree has el domeinn name and a full do mhuin name and a full damain name is a sequence of symbols specified by dots. - It translates the domain name into IP address this allow the users of networks to utilize user- frindly names when looking for other hearts instead of remembering the IP addresses. ### Internet Explorer - Is a product from Software giant microsoft this is the most commonly ured brouser in the universe. This was introduced in 1995 along with windows 95 lounch and it has Rasseel Netscope popularity in 1998. - By 2003 it has attained almart 95% of usage share and had become the most popular browser of all- - It was included in the microsoft windous operating rystem. - In 2015, it was replaced with "microsoft elge" as it the defoult browser on windows 10. ### Mosaic - It was launched in 1993. - It was the second or browser which wees launched. - Had a better graphical interface, imeges text and graphies could all be integrated. ### Netscopes Navigator - It was released in 1994. - More version of this browser were launched by Netscape. - It had an advanel licensing scheme and allowed for usage for non-Commercial purposes. ### Firefox - It was intero lived in 2022 and was developel by mozilla foundation firefox overtook the usage share from intennet explorer and become the dominant browser. - Location coware browseing was made avaikable with fire fox. This browser was also made available for mobile phones, tablets etc. ### Google Chrome - It was launched in 2008 by broogle. - It is a cross plateform web browser. - Multiple feature from old browser were amalgamated to form better and never features. - To save computers forom mobile, broogle eleveloped the blocking feature to keep the user data safe and secure. - Incognito made is provided, where private searching is avaible, where no cookies or history is saved. - It has the best user interface- ### Searching the www.w directories - A web directory is a hand made list of webrites. Also known as a rubject directory, these list create an organized method for finding webrites. - It's similar but not identical to a search engine. The result of a web elirectory is an easily digertibls list of links Organized within cary to find webrites by subject. - A directory make in comman cectegoris. - A directory is useful for finding webrites through key bords. ### A Meta Search Erigine - The meter search engine is a type of serach engine that gives results based on a combination of results from other search engine dater base. It specializes in concatenating database from variety of search engines and linking search results to relevant sources. - Meta search engines use a complex algorithm that allows virtual databases to be generated on the Ely. A virtual data buse "virtually" morrers the physical later base results of other are " searchengines. All search- results information and data are listed in a virtual database and searches may be concentreated accoreling to Varid criteriu. - This no two meta search engines are a like because they all operate with different on the algorithm designed to performspeciful search functions. - Metasearch engings ere way to get a wide range of search results from different search engine. - Ameter search engine takes the uniquery you have entered and gothers results foram multiple search engines online such as google Yah. - they aggregati the result for you so you can choose the bert Information from the search provied. ### Advantages - By sending multiple vueries to s cuired ather search engines this extends the coverage deta of the topic and allows more information to be founded- - A meta search engine has an advantage ower a single search engine be cause more results can be retrieved with the same. amount of exertion. - It also reduces the work of users form having to individuly type in search foromelifferent ensinart. ### Disadvantes - The number of thy perlinks generated by meta search engines are limited and there fare do not provide the user with the complete results - of a very meta search engines are not capable of perring query forms or able to fully translate query syntax- ### Fundemental Search - The internet contains a vast collectior of information, which is spread out in every part of the world on remote web eservers. - The Problem in lo ceding the correct information on the internet led to the creation of search technology known as Internet search engine. - A search engine can provide links to rebevant information based on your requirement or I or query. - In order to understand the technology and techniques to partion our website page for higher ranking in search engines the knowledge of the baric s function of a search enging is essential. ### Functions of Internet Search Engine - Each search engine cdies the same functions of callecting, organizing in elexing and seruing results in its own unique ways thus employing various algarithns, algo and technolgo short the function search engine can be categoried into the following #### 1. Crawling and spidering the **web** - The cred crawler (also known as a web robot ar web spider) is a software Program that can be download weld content and follow hyperlinks within these web contents to downloads to the linked contects. #### 2. BHA Building The index - Search engines must store the information in a way that makes it useful- #### 3. Staring the web site contents. #### 4. search algorithms & Results- ## A Search Engine - Is a software that searches a data base of information eccording to the useres query. - The engine provides a list of result that best match what the user is trying of find. - Today there are many different searchengines avaible on. the internet each with its our abilites and features. - The first search engine ever develped is considered Archie which was useel to search for FTP files and the first text based search engine is considered veronica. - Currently the most popular and well known search engine is google. - Exs Bing Index, Yahee google. ### How to access a search engine - The search engine for a website is at the top or reede of each page on a well designed website. - Ex - On computer Hope our search engine shows you results only from that webrite and not the entire Internet. - Also some companies may have additional features to make uring their search easier. - In our care we use a curtom techonlogy called hope, but that helps edirect visitars using our search. ### How a searchengine Works - A spider/corouler, dictionary, online help & contact help. - Index of page crawled, contact dictionary help online. - Index data processed eind brokeup. and Processed elata moved to other computers, files and for partions of memory- ### Search engine data is callected using a espider or crawler that visits each page on the internet and collectsits information, Once expage is crawled the dater contained the Rage is processed and in dexed of ten, this can inuolus the step below- - Strip out stop words. - Record the remaining words on the page and the frequncy they Ocur. - Record links to other pages. - Recoord information about any images audio and embedded media on the page...... - Finely Once the data is processed its broken up into files inserted into a data or loaded into momory. - Search engines can differ from one to another in their ways of Providing the answers to the user but all of them are buit 3 fumedamental principles. ### Crawling - The actual discovery of new webpages on the internet starts with the process called Crawling - Searchengines use small programs called web crawlings- (sometimes called buts or spiderbots) that fallow links. - Forom already known pages to the new ones that need to be discovered. - Every time a web crawler finds a new webpage through a link it scams and passes its content for further processing (calleel indexing) and continuser in the discovery of new web pages - ### Indexing - Once the bats crow the data its time time for indexing. - The process of valideting and storing the Content from the web pages in the search engines elata base called "Index". - It is basically ably indexing of all the webrites. - Your websites has to be indexed in order to be displayed on the search engine results page. - Keep in mind that both crawling and indexing are continuous processes that feike place oure and over again to keep the data base fresh. ### Ranking - The last step includes picking the best result ere and creating a list will upper on the result page. - Every search engine uses dozens of sanking signals and most of them are kept as a search unavaitable to the public. ### Telnet - The telnet developed in 1969 is a proto cal that proidus Communication with a remate device on server sometimes comployed for remate mangement but also for initial device setup, with a command line inder face for Telent types Network, but it can also be use as a like network hardware, Telent stands for Verb to telnet to is to establish a connection using the telnet protocol.. ### How does Telnet work - Telnet provides users with a bidirectional interactive text oriented communication system utilizing a curtual terminal connection over 8 byte User data is interspersed in band with telnet control information over TCP (Transmission control Protocol). - Often telnet was used on a terminal to ex cente functions remotely by using the Telnet protocol, which means entering telnet into a Command prompt. - The user connects to the server by following this syn syntax. Telnet hostname port. - The user them executes commands on the server by using specifie Telnet commands into the telnet pirompt. - Joend a serrion and log off the user ends e Telnet command with Telnet. ### Is Telnet Secure - Because it was developed befor the main stream adaptation of the internet, Telnet on its owndoes not employ any form of encryption making it out dated in terms of modern security, If has largely been overlopped by Secure shell (SSH) protocal which has its own security considerations around remote access) at least on the public internet- - but for instanes where Telnet is still in use public are afew methods for securing your communications. ### What are common uses for Telnet? - Telnet can be used to test or troubleshoot remote web or mail servers as well as for remote access to MUDS (multi-user dungeon games) and trusted, internal networks. ### FTP - Stands for File Transfier Protocol. - FTP is a standard internet protocol providay by TCP/IP used for transmatling the files from one thost to another. - It is mainly used for transferring the web page files freem their ceaten to the computer that acts as er server for other computers on the internet. - It is also used for downloading the files to computer from other servers. ### Objectives of FTP - It provides the sharing of files- - It is used to encourage the use of remote computers - - It is used transfers the date more relidly and efficiently. ### Why FTP - Although transferring files from one system to another is very simple and Storaightforward, but sometimes it con cause problems. - For example two systems may have different file conventions. - Two systems may have different ways to Represent text and data. Two systems may have differne directory structures. - FTP protocol over comes these problems by establishing two connections between tharts. One Connection is useel for data transfer and another connection is used for the control connection. ### FTP Connections - Control Connection, Data Connection ### Control Connections - The control connection uses very simple rules for commanication through control connection. - We contransfer a line of Command or line of response at a time. - The control Connection made between the contreal processes. - The control Connection remains connected during the entire interactive FTP session. ### Data Connections -& The Data Connection uses very complex rules as data types may vary. - The data Connection is made between data transfer processes. - The deuter connection opens when a command comes for Fransfering the file and clerres when the fill is transferer. ### Advantages of FTP - The biggest advantages of FTP is speed. - The FTP is one of the fastert way to transfer the files from one computer to in other computer. - It is mare efficient as we do not need to Complel all the operations to get the entire file. - Security To access the FTP server we ces need to login with user name and password. Therefore, we can sey that FTPis more secure. - Back and forth movement FTP allows us to transfer the files back and forth. - Suppose you are a manager of the company you send some information to all the employees and they all send information back on the same server. ### Disadvantages of FTP - The standard requirement of the industry is that not all the FTP Providers are equal and not all the providers offer encryption. - So we will have to look out provides o for the FTP providers that provider encryption. - It is compatible with every system.