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UNIT-11) Evolution of Internet & WWW :--From

Forouzan2) Review of TCP/IP:--Forouzan3) Architecture:--Tannen baum4) DNS:--tannen baum

5)How Internet Works(Working of Internet):--

Because the Internet is a global network of computers each computer connected to the Internet must have a unique address. Internet addresses arein the form nnn.nnn.nnn.nnn where nnn must be a number from 0 - 255.This address is known as an IP address. (IP stands for Internet Protocol;more on this later.)

The picture below illustrates two computers connected to the Internet; your computer with IP address 1.2.3.4 and another computer with IP address5.6.7.8. The Internet is represented as an abstract object in-between. (As this

paper progresses, the Internet portion of Diagram 1 will be explained andredrawn several times as the details of the Internet are exposed.)

If you connect to the Internet through an Internet Service Provider (ISP),you are usually assigned a temporary IP address for the duration of your dial-in session. If you connect to the Internet from a local area network (LAN) your computer might have a permanent IP address or it mightobtain a temporary one from a DHCP (Dynamic Host ConfigurationProtocol) server. In any case, if you are connected to the Internet, your computer has a unique IP address.

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the message must be translated from alphabetic text into electronicsignals, transmitted over the Internet, then translated back into alphabetictext. How is this accomplished? Through the use of a protocol stack .Every computer needs one to communicate on the Internet and it isusually built into the computer's operating system (i.e. Windows, Unix,etc.). The protocol stack used on the Internet is referred to as the TCP/IP

protocol stack because of the two major communication protocols used.The TCP/IP stack looks like this:

Protocol layers CommentsApplication protocol layer Protocol specific 2 application

i.e.www,email,FTP etcTransmission control protocol layer TCP directs 2 a specific on a

computer using a port no.Internet protocol layer IP directs packets 2 a specific

computer using an IP address.Hardware Layer Converts Binary packet data into a

n/w signals & back(i.e. Ethernet n/wcard,MODEM for phone lines)

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1. The message would start at the top of the protocol stack on your computer and work it's way downward.

2. If the message to be sent is long, each stack layer that the message passes through may break the message up into smaller chunks of data.This is because data sent over the Internet (and most computer networks) are sent in manageable chunks. On the Internet, thesechunks of data are known as packets .

3. The packets would go through the Application Layer and continue tothe TCP layer. Each packet is assigned a port number . Ports will beexplained later, but suffice to say that many programs may be usingthe TCP/IP stack and sending messages. We need to know which

program on the destination computer needs to receive the message because it will be listening on a specific port.

4. After going through the TCP layer, the packets proceed to the IP

layer. This is where each packet receives it's destination address.

5. Now that our message packets have a port number and an IP address,they are ready to be sent over the Internet. The hardware layer takescare of turning our packets containing the alphabetic text of our message into electronic signals and transmitting them over the phoneline.

6. On the other end of the phone line your ISP has a direct connection tothe Internet. The ISPs router examines the destination address in each

packet and determines where to send it. Often, the packet's next stopis another router. More on routers and Internet infrastructure later.

7. Eventually, the packets reach computer, the packets start at the bottomof the destination computer's TCP/IP stack and work upwards.

8. As the packets go upwards through the stack, all routing data that thesending computer's stack added (such as IP address and port number)is stripped from the packets.

9. When the data reaches the top of the stack, the packets have been re-

assembled into their original form.

7)Architecture of Internet:--

#Internet Backbone:--

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The Internet backbone is made up of many large networks whichinterconnect with each other. These large networks are known as Network Service Providers or NSP s. Some of the large NSPs are UUNet, CerfNet,IBM, BBN Planet, SprintNet, PSINet, as well as others. These networkspeer with each other to exchange packet traffic. Each NSP is required toconnect to three Network Access Points or NAP s. At the NAPs, packettraffic may jump from one NSP's backbone to another NSP's backbone.

NSPs also interconnect at Metropolitan Area Exchanges or MAE s. MAEsserve the same purpose as the NAPs but are privately owned. NAPs were theoriginal Internet interconnect points. Both NAPs and MAEs are referred toas Internet Exchange Points or IX s. NSPs also sell bandwidth to smaller networks, such as ISPs and smaller bandwidth providers. Below is a pictureshowing this hierarchical infrastructure.

This is not a true representation of an actual piece of the Internet.Diagram 4 is only meant to demonstrate how the NSPs could

interconnect with each other and smaller ISPs. None of the physicalnetwork components are shown in Diagram 4 as they are in Diagram 3.This is because a single NSP's backbone infrastructure is a complexdrawing by itself. Most NSPs publish maps of their network infrastructure on their web sites and can be found easily. To draw anactual map of the Internet would be nearly impossible due to it's size,complexity, and ever changing structure .

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The Internet Routing Hierarchy

So how do packets find their way across the Internet? Does every computer connected to the Internet know where the other computers are? Do packetssimply get 'broadcast' to every computer on the Internet? The answer to boththe preceding questions is 'no'. No computer knows where any of the other computers are, and packets do not get sent to every computer. Theinformation used to get packets to their destinations are contained in routingtables kept by each router connected to the Internet.

Routers are packet switches. A router is usually connected between

networks to route packets between them. Each router knows about it's sub-networks and which IP addresses they use. The router usually doesn't knowwhat IP addresses are 'above' it. Examine Diagram 5 below. The black boxesconnecting the backbones are routers. The larger NSP backbones at the topare connected at a NAP. Under them are several sub-networks, and under them, more sub-networks. At the bottom are two local area networks withcomputers attached.

Diagram

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When a packet arrives at a router, the router examines the IP address putthere by the IP protocol layer on the originating computer. The router checks it's routing table. If the network containing the IP address isfound, the packet is sent to that network. If the network containing the IPaddress is not found, then the router sends the packet on a default route,usually up the backbone hierarchy to the next router. Hopefully the nextrouter will know where to send the packet. If it does not, again the packetis routed upwards until it reaches a NSP backbone. The routers connectedto the NSP backbones hold the largest routing tables and here the packetwill be routed to the correct backbone, where it will begin its journey'downward' through smaller and smaller networks until it finds it'sdestination.

8)Basic hardware tools of Internet Access:--(Tannen baum)

S/W Tools for Internet Access:--

1)ISP:- An Internet service provider (ISP), also sometimes referred to asan Internet access provider (IAP), is a company that offers its customersaccess to the Internet. The ISP connects to its customers using a datatransmission technology appropriate for delivering Internet Protocol Paradigm , such as dial-up , DSL, cable modem , wireless or dedicated

high-speed interconnects. ...

2)MODEM:- A modem (modulator-demodulator) is a device thatmodulates an analog carrier signal to encode digital information, and alsodemodulates such a carrier signal to decode the transmitted information.The goal is to produce a signal that can be transmitted easily and decodedto reproduce the original digital data. Modems can be used over anymeans of transmitting analog signals, from driven diodes to radio.For internet access it is used……..

1. Computer with Internet connection. PC or Macintosh is fine. Youcan also browse the Net with a Pocket PC, a WebTV, or even a Citrixor Sparc workstation, if it is setup correctly. As you might know,there are coffee shop "Internet Cafes" that will rent usage of connected computers to you.2. Internet account with a connection provider. Often called "ISP"(Internet Service Provider), these are usually phone or cable

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companies that charge you $20 to $80 USD a month for internetaccess. Note: if you browse the Net from work, your company eatsthis cost as part of their operations. They also will have rules for youto follow. If you browse from an Internet Cafe, you will need to pay

perhaps $6 USD per hour.3. Internet browser software. The most popular is called InternetExplorer version 7 or 8 ("IE"). The the second most common browser is Mozilla Firefox. Other browser choices include: Chrome, AOL,Opera, and Netscape.4. Anti-virus software. Symantec/Norton or McAffee are two of thethe most common. Avira Antivirus is my personal favorite. Thesewill help defend you against nasty programs that will erase parts of your hard drive.5. Email software. You can choose from the very popular Outlook or

Outlook Express, less-common email softwares like Eudora or Groupwise, or the free "web-mail" offered by Yahoo or Hotmail or Gmail.com.6. Plug-In software. This is a big topic in its own right, but here arethe most-common you will need: Java Virtual Machine, MacromediaFlash Player, Windows Media Player, Real Audio music player,Apple Quick Time.7. Optional: stereo speakers, microphone, and webcam. Thesehardware devices will allow you to hear game sounds, do Internettelephoning, and send images to your friends and family.8. Optional: Anti-Spam software.9. Optional: Censorware , to help police what your kids can see.10. Optional: graphic software, so you can edit pictures you like.11. Optional: printer.12. Optional: wheel mouse, to quickly scroll pages up and down .

9)ISP:--

Following graphic give a typical view of current major ISP architectures,and depending on the number of physical boxes could be extended from fewthousand to few million users.

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Definition: An ISP is a company that supplies Internet connectivity to homeand business customers. ISPs support one or more forms of Internet access,ranging from traditional modem dial-up to DSL and cable modem

broadband service to dedicated T1/T3 lines.

More recently, wireless Internet service providers or WISPs have emergedthat offer Internet access through wireless LAN or wireless broadbandnetworks.

In addition to basic connectivity, many ISPs also offer related Internetservices like email, Web hosting and access to software tools.

There are various terms related to the Internet. For explaining how an ISPworks, certain terms need to be presented before starting with the actualworking.

Modem: Every computer that connects to the internet has to do so using amodem. The full form of modem is 'modulator-demodulator'. The functionof the modem is synonymous to its name. It modulates the data and converts

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it into digital form before passing on the information to the Internet service provider. The data that it receives from the Internet service provider is alsoin the form of digital signal, and so it demodulates the data.

IP Address: IP stands for Internet Protocol. Every computer that connects tothe internet is assigned an IP address by the ISP. When we type in the nameof a particular website in our web browser, we are actually typing in theInternet Protocol address of the website. The IP address in this case is theaddress of the server machine that holds the desired web pages. It isgenerally of the form n.n.n.n, where n stands for a number.

DHCP: 'Dynamic Host Control Protocol' in its abbreviated form is known asDHCP. A protocol is nothing but a set of rules that decides the process of doing a work. The dynamic host control protocol is used by the ISP to assign

temporary addresses to any of its subscribers who intend to connect to theInternet.

Backbone of ISP: This is the point that connects your ISP to the Internet.The ISPs buy a particular range of bandwidth for the working of its

backbone. It is through this bandwidth that information is sent or received.

The ISP FacilityThe Internet service provider carries out its entire functioning in a roomcalled the data center. The advanced data centers consists of variousequipments. However, for the ease of explaining how an ISP works, I willintroduce you to the basic equipments which carry out the Internetconnection procedure. A pool of modems inside the data center is used toconnect every subscriber to the Internet. Once a modem in the modem poolreceives the information, it connects the subscriber to the backbone. Theentire functioning of the modem pool is controlled by algorithms running ina computer to which the modems are connected. This setup of modems isgenerally referred to as the ISP port server.

How does an ISP Work?Let's start with the procedure right from the local computer. Homecomputers connect to the ISP using telephone cables or broadband Internet connections. Large networks like that of educational institutes connect to theISP using a D1 line. The way of logging into the ISP is however same for

both. For connecting to the Internet, you will need a modem and an ISP

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subscription. Let's try to understand the entire procedure in a step by step process:

• The first step is to login into the ISP using the user information provided to you by your ISP. Here, you enter the username, passwordand telephone number of the ISP.

• Once the ISP receives your information in its modem pool, it verifiesif you are an authentic user or not.

• Once the user authentication process is done, the ISP provides youwith a dynamic IP address using the DHCP.

• If you have bought a static IP from your ISP, then this step is notrequired. However, buying a static IP will cost you a lot.

• Now, you are allowed to browse any web page through your web browser. When you type in the name of the URL on the address bar,

you are actually requesting for the IP address of the server machine,that holds those web pages.

• The information is received at the modem pool. Once this informationis received, the ISP connects the subscriber to the modem pool.

• The requested server machine is reached through an array of dedicatedlines and routers.

• Once the ISP finds the required IP address, it transfers the requestedweb pages to the source IP address.

Cooling devices and backup power supplies are among the other components used by an ISP. These components are of utmost importance for the effective functioning of the ISP.

10)Internet Services:--

1) Information:-

World Wide Web browser software, such as Microsoft 's Internet Explorer ,Mozilla Firefox , Opera , Apple 's Safari , and Google Chrome , let usersnavigate from one web page to another via hyperlinks embedded in thedocuments. These documents may also contain any combination of computer data , including graphics, sounds, text , video , multimedia andinteractive content including games , office applications and scientificdemonstrations. Through keyword -driven Internet research using search

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engines like Yahoo! and Google , users worldwide have easy, instant accessto a vast and diverse amount of online information. Compared to printedencyclopedias and traditional libraries , the World Wide Web has enabled thedecentralization of information.

The Web has also enabled individuals and organizations to publish ideas andinformation to a potentially large audience online at greatly reduced expenseand time delay.

Advertising on popular web pages can be lucrative, and e-commerce or thesale of products and services directly via the Web continues to grow. In theearly days, web pages were usually created as sets of complete and isolatedHTML text files stored on a web server.

2) Communication:-E-mail is an important communications service available on the Internet.The concept of sending electronic text messages between parties in a wayanalogous to mailing letters or memos predates the creation of the Internet.Pictures, documents and other files can be sent as e-mail attachments . E-mails can be cc-ed to multiple e-mail addresses .

3)Data transfer:-File sharing is an example of transferring large amounts of data across theInternet. A computer file can be e-mailed to customers, colleagues andfriends as an attachment . It can be uploaded to a website or FTP server for easy download by others.Streaming media refers to the act that many existing radio and television

broadcasters promote Internet "feeds" of their live audio and video streams(for example, the BBC ). They may also allow time-shift viewing or listeningsuch as Preview, Classic Clips and Listen Again features.

4)Access:-The prevalent language for communication on the Internet is English . After English (28% of Web visitors) the most requested languages on the WorldWide Web are Chinese (23%), Spanish (8%), Japanese (5%), Portuguese andGerman (4% each), Arabic , French and Russian (3% each), and Korean (2%). [16] By region, 42% of the world's Internet users are based in Asia , 24%in Europe , 14% in North America , 10% in Latin America and the Caribbean taken together, 5% in Africa , 3% in the Middle East and 1% in

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Australia /Oceania . The Internet's technologies have developed enough inrecent years, especially in the use of Unicode , that good facilities areavailable for development and communication in the world's widely usedlanguages.ommon methods of Internet access in homes include dial-up , landline

broadband (over coaxial cable , fiber optic or copper wires), Wi-Fi , satellite and 3G technology cell phones ..

Social impact:-

The Internet has enabled entirely new forms of social interaction,activities, and organizing, thanks to its basic features such as widespreadusability and access. Social networking websites such as Facebook ,

Twitter and MySpace have created new ways to socialize and interact.Users of these sites are able to add a wide variety of information to

pages, to pursue common interests, and to connect with others. YouTube and Flickr specialize in users' videos and photographs.

6)WWW7)News-groups/Entertainment etc..

11)Internet Account:--

To connect to the Internet, you can use one of several types of accounts:Internet PPP accounts (using a dial-up, ISDN, or DSL line), cable Internetaccounts, or online services. You can also use an old-fashioned text-basedaccount ..

Internet (PPP) Accounts

A PPP (Point-to-Point Protocol) account is an Internet account that uses thePPP communications protocol. PPP is the most popular type of Internetaccount because the most popular software--Internet Explorer, Netscape

Navigator, Outlook Express, Eudora, and other programs--is designed towork with PPP accounts. Occasionally, you may run into a SLIP (Serial LineInternet Protocol) or CSLIP account (Compressed SLIP), which are old,less-reliable protocols than PPP, but which work the same way. This book refers to PPP, CSLIP, and SLIP accounts as dial-up Internet accounts.

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An Internet service provider (ISP) is an organization that provides Internetaccounts, usually PPP accounts, but occasionally UNIX shell accounts. AllISPs provide dial-in accounts using regular phone lines, and many also

provide ISDN and DSL connections .

Dial-Up Internet Accounts, Including ISDN

To connect to an Internet account over a dial-up phone line, you need aPPP-, CSLIP-, or SLIP-compatible communications program, which is builtinto Windows. Windows Network Connections can dial the phone by usingyour modem, connect to your ISP, log into your account by using your user name and password, and then establish a PPP, CSLIP, or SLIP connection,so your computer is connected to the Internet. While connected, you can use

a variety of Winsock-compatible programs to read your e-mail, browse theWeb, and access other information from the Internet. When you are done,you tell Windows to disconnect from your Internet account. You configureyour network connection by using the New Connection Wizard. You canalso create and edit network connections manually.

DSL Accounts

If you want to use a high-speed Internet account, check with local andnational ISPs to find out which ones offer DSL in your area. If your ISPoffers ISDN or DSL accounts, they can work with your telephone companyto get the high-speed phone line installed and tell you the type of ISDN or DSL modem you need. See the section "Connecting to a DSL Line " inChapter 21 for how to configure Windows to work with a high-speedaccount.

UNIX Shell Accounts and Bulletin Board Systems

Before the advent of PPP and SLIP accounts, most Internet accounts weretext-only UNIX shell accounts. You run a terminal-emulation program (a

program that allows your PC to pretend it's a computer terminal) on your PCto connect to an Internet host computer. Most Internet hosts run UNIX, a

powerful but frequently confusing operating system, and you have to typeUNIX commands to use a UNIX shell account. To send and receive e-mailor browse the Web, you run text-only programs, such as pine (the most

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popular UNIX e-mail program) and Lynx (the most widely used UNIX Web browser). UNIX shell accounts don't let you see graphics, use a mouse, or easily store information on your own computer.

Cable Internet Accounts

With a cable Internet account, your cable television company is your ISP,and you connect to the Internet over your cable. Contact your cable companyto find out whether it offers Internet accounts. If it does, sign up to open anaccount. The monthly fee usually includes the rental of a cable modem. See" Configuring Windows for a Cable Modem " in Chapter 21 for anexplanation of how to configure Windows to work with a cable Internetaccount.

Online Services

An online service is a commercial service that enables you to connect andaccess its proprietary information system. Most online services also providean Internet connection, e-mail, access to the Web, and sometimes other Internet services. Online services usually require special programs toconnect to and use your account. Previous U.S. versions of Windows camewith signup programs for some online services.

The two most popular online services in the United States are AmericaOnline (AOL) and CompuServe (CIS), which is owned by AOL. TheMicrosoft Network (MSN) started out as an online service, but has beenrelaunched as an ISP. AOL and CompuServe let you use some Winsock-compatible programs while you are connected to the account. For example,you can use the Internet Explorer or Netscape Navigator Web browsers withany of these accounts. However, AOL doesn't support standard e-mail

programs--you have to use their software (or their Web site) to read your mail.

AOL is available in the United States, Canada, and the U.K., with other countries being added. The latest version of the America Online software (asof 2001) is 6.0, but 7.0 is on the way. To sign up for an AOL account, installand run the AOL software. Download the software from the AOL Web site,if you haven't already received it on a CD-ROM bound into a magazine or ina direct mail solicitation. Windows XP may come with the AOL software

pre-installed, especially if you buy a computer with Windows XP

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preinstalled. The program steps you through connecting to AOL using anexisting account, or signing you up for a new one.

The Microsoft Network (MSN)

Microsoft Network (MSN) was Microsoft's entrant in the world of onlineservices in 1995. Although MSN has gained a lot of users because of theeasy-to-click icon on the Windows 95, 98, and Me desktops, it's never beenas highly rated as AOL or CompuServe. Microsoft has changed MSN froman online service to a regular Internet service, so you now use network connections to connect to MSN and Winsock programs to access itsservices.

When you start Internet Explorer, you usually start at the MSN portal Web

site (http://www.msn.com, which is accessible no matter what kind of Internet account you use.

12)Internet Connectivity:--

Internet connection types:In order to connect to the internet, a worldwide community of interconnected computers and information, you must pay a service provider for a connection. This is much the same as paying the phone company for connection to the worldwide phone grid. The difference is that the internet isthe same price whether you communicate with someone in Japan or your next door neighbor.There are four main types of internet connections common to the general

public:

1.)DSL (128Kbps to 8Mbps):-

DSL is also called an always on connection because it uses existing 2-

wire copper telephone line connected to the premise and will not tieup your phone as a dial-up connection does. There is no need todial-in to your ISP as DSL is always on. The two main categories of DSL for home subscribers are called ADSL and SDSL.

ADSLADSL is the most commonly deployed types of DSL in North America.

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Short for asymmetric digital subscriber line ADSL supports data rates of from 1.5 to 9 Mbps when receiving data (known as the downstream rate) andfrom 16 to 640 Kbps when sending data (known as the upstream rate).ADSL requires a special ADSL modem.

ADSL+2ADSL+2 A is an extension to ADSL broadband technology that providessubscribers with significantly faster download speeds when compared totraditional ADSL connections. ADSL+2 works in the same fashion as ADSLa special filter is installed on a subscriber's telephone line to split existingcopper telephone lines (POTS) between regular telephone (voice) andADSL+2. ADSL2+ service is most commonly offered in highly-populatedmetropolitan areas and subscribers must be in close geographical locationsto the provider's central office to receive ADSL2+ service.

SDSLSDSL is still more common in Europe. Short for symmetric digitalsubscriber line, a technology that allows more data to be sent over existingcopper telephone lines (POTS). SDSL supports data rates up to 3 Mbps.SDSL works by sending digital pulses in the high-frequency area of telephone wires and can not operate simultaneously with voice connectionsover the same wires. SDSL requires a special SDSL modem. SDSL is calledsymmetric because it supports the same data rates for upstream anddownstream traffic.

VDSLVery High DSL ( VDSL ) is a DSL technology that offers fast data rates over relatively short distances — the shorter the distance, the faster theconnection rate.

• All types of DSL technologies are collectively referred to as xDSL.• xDSL connection speeds range from 128 Kbps to 8 Mbps.

2.) Dial-up:This method of connecting to the internet is the oldest and slowest method.It is also the most readily available in all places which also receive phoneservice. Using this type of connection requires connecting a phone line intoyour PC and using a modem to communicate through the phone line. While

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in use by your computer, you may not use your phone line. Many people payfor a second line dedicated directly to their dial-up connection much as

business might with fax lines .

3) Cable:This method of connection is also many times faster than dial-up. In thiscase, your PC is connected to a cable modem which is then connectedthrough your cable TV lines at your house. Since this wire is separate fromyour phone line, you may watch tv, talk on the phone, and connect to theinternet all at the same time.

Cable speeds range from 512 Kbps to 20 Mbps.

4) FiOs (Fiber Optic):

This method of connection is the fastest available to most home users. Fiber optic internet connections work in the same way as DSL or Cableconnections do, except that a fiber optic line is run from the telephone poledirectly to your location. As with other high speed lines, you may use the

phone, tv, and computer all at the same time. The advantage of fiber optics isits speed advantage capabilities over DSL and cable .

Wireless Internet Connections:-

Wireless Internet, or wireless broadband is one of the newest Internetconnection types. Instead of using telephone or cable networks for your Internet connection, you use radio frequency bands. Wireless Internet

provides an always-on connection which can be accessed from anywhere — as long as you geographically within a network coverage area. Wirelessaccess is still considered to be relatively new, and it may be difficult to finda wireless service provider in some areas. It is typically more expensive andmainly available in metropolitan areas.

T-1 Lines(Radio link)

T-1 lines are a popular leased line option for businesses connecting to theInternet and for Internet Service Providers (ISPs) connecting to the Internet backbone. It is a dedicated phone connection supporting data rates of 1.544Mbps. A T-1 line actually consists of 24 individual channels, each of which supports 64Kbits per second. Each 64Kbit/second channel can beconfigured to carry voice or data traffic. Most telephone companies allow

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you to buy just one or some of these individual channels. This is known asas fractional T-1 access .

Bonded T-1A bonded T-1 is two or more T-1 lines that have been joined (bonded)together to increase bandwidth. Where a single T-1 provides approximately1.5Mbps, two bonded T1s provide 3Mbps or 46 channels for voice or data.Two bonded T-1s allow you to use the full bandwidth of 3Mbps where twoindividual T-1s can still only use a maximum of 1.5Mbps at one time. To be

bonded the T-1 must run into the same router at the end, meaning they mustrun to the same ISP.

• T-1 Lines support speeds of 1.544 Mbps•

Fractional T-1 speeds are 64 Kbps per channel (up to1.544 Mbps), depending on number of leased channels.• Typical Bonded T-1 (two bonded T-1 lines) speed isaround 3 Mbps.

T-3 LinesT-3 lines are dedicated phone connections supporting data rates of about 43to 45 Mbps. It too is a popular leased line option. A T-3 line actuallyconsists of 672 individual channels, each of which supports 64 Kbps. T-3lines are used mainly by Internet Service Providers (ISPs) connecting to theInternet backbone and for the backbone itself.

• Typical T-3 supports speeds ranging from 43 to 45 Mbps.

Satellite(VSAT)Internet over Satellite (IoS) allows a user to access the Internet via a satellitethat orbits the earth. A satellite is placed at a static point above the earth'ssurface, in a fixed position. Because of the enormous distances signals musttravel from the earth up to the satellite and back again, IoS is slightly slower than high-speed terrestrial connections over copper or fiber optic cables.

• Typical Internet over Satellite connection speeds (standard IP services) average around 492 up to 512 Kbps.

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UNIT-3

1)Web Hosting services:-- By sir’s Notes

2)WWW/Web Server:-- By sir’s Notes3)HTTP:-- Forouzan4)URL:-- Forouzan5)Web Searching :--Principle,Types,examples—By sir’s Notes6)Web browser:-- By sir’s Notes and tannenbaum

7)Multiple sites on a single server:-- IIS supports multiple Web siteson a single server. For example, rather than using three different servers tohost three different Web sites, you can install all three Web sites on the sameserver. Consolidating Web sites saves hardware resources, conserves space,and reduces energy costs.

To ensure that user requests reach the correct Web site, you must configure aunique identity for each site on the server. To do so, you must distinguisheach Web site with at least one of three unique identifiers: a host header name, an IP address, or a unique TCP port number.

Web sites hosted on the same server can be distinguished using thefollowing unique identifiers.

•Host header name•IP address•TCP port number

IIS Manager (IIS 6.0)

IIS Manager is a graphical interface for configuring your application poolsor your Web, FTP, SMTP, or NNTP sites. With IIS Manager, you canconfigure IIS security, performance, and reliability features. You can add or delete sites; start, stop, and pause sites; back up and restore server configurations; and create virtual directories for better content management,to name only a few of the administrative capabilities. In previous releases of IIS, this tool was called the In

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1) Creating Multiple Sites Using IP address(IIS 6.0)

Some server configurations require the use of unique IP addresses todistinguish multiple Web sites on the same server.

IIS enables you to configure Web sites to listen on all available IP addresses,or on an individual IP address. If you use multiple IP addresses todistinguish between different sites on the same server, you must configureIIS to assign each site a unique IP address.

Procedures:-

1.In IIS Manager , expand the local computer, right-click the Web Sitesdirectory, point to New , and then click Web Site .

2.Click Next .

3.In the Description box, type the name you have selected for the Web site,and click Next .

4.In the Enter the IP address to use for this Web site box, click the uniqueIP address reserved for this site.

5.In the TCP port this Web site should use box, type the port number used by all sites on the server. This should typically be left at the default of 80.

6.If SSL encryption is enabled on the server, type the SSL port number, andthen click Next . If SSL encryption is not enabled on the server, the SSLport box does not appear.

7.In the Path box, type or browse to the path of your Web site homedirectory.

8.To create a secured or private Web site, clear the Allow anonymousaccess to this Web site check box, and then click Next . (Web sites areconfigured for anonymous access by default.)

9.In the Web Site Access Permissions box, set the permissions for the homedirectory.

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10.Click Next , and then click Finish .

2) Creating Multiple Sites Using Host Header Names (IIS 6.0)

Every Web site has a descriptive name, and can support one or more hostheader names. Organizations that host multiple Web sites on a single server often use host headers because this method enables them to create multipleWeb site identities without using a unique IP address for each site.

Procedures:-

1.In IIS Manager , expand the local computer, right-click the Web Sites

directory, point to New , and then click Web Site .

2.Click Next .

3.In the Description box, type the name you have selected for the Web site,and then click Next .

4.In the Enter the IP address to use for this Web site box, click the IPaddress used by all sites on the server.

5.In the TCP port this Web site should use box, type the port number used by all sites on the server.

6.In the Host Header for this Web site (Default:None) box, type the hostheader name to identify the Web site. The host header name must containthe full name of the site, for example, www.microsoft.com.

7.If SSL encryption is not enabled on the server, the SSL port box does notappear. If SSL encryption is enabled on the server, type the SSL portnumber, and then click Next . Note that you cannot use host headers with

SSL encryption.

8.In the Path box, type or browse to the path of your Web site homedirectory.

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9.To create a secured or private Web site, clear the Allow anonymousaccess to this Web site check box, and click Next . (Web sites areconfigured for anonymous access by default.)

10.In the Web Site Access Permissions box, set the permissions for thehome directory.

11.Click Next , and then click Finish .

3) Creating Multiple Sites Using Ports (IIS 6.0):-

you can use nonstandard TCP port numbers to create unique Web siteidentifiers for site development and testing purposes. You can do this

by creating a Web site identity that consists of a TCP/IP address or host

header name, appended with a nonstandard TCP port number. BecauseTCP/IP endpoints are defined by a combination of IP address (or thecorresponding name) and port number, configuring a Web site with anonstandard port number creates a unique endpoint, or identity, for thesite.

Procedures:-

1.In IIS Manager , expand the local computer, right-click the Web Sitesdirectory, point to New , and then click Web Site .

2.In the Web Site Creation Wizard, click Next .

3.In the Description box, type the name that you have selected for the Website, and then click Next .

4.In the Enter the IP address to use for this Web site box, click the IPaddress used for all sites on this server.

5.In the TCP port this Web site should use box, type the unique portnumber reserved for this site.

6.Optional: In the Host Header for this Web site (Default:None) box, typethe host header name to identify the Web site. The host header name mustcontaining the full name of the site, for example, www.microsoft.com.

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7.If SSL encryption is enabled on the server, type the SSL port number, andthen click Next . If SSL encryption is not enabled on the server, the SSLport box does not appear.

8.In the Path box, type or browse to the path of your Web site homedirectory.

9.To create a secured or private Web site, clear the Allow anonymousaccess to this Web site check box, and click Next. (Web sites areconfigured for anonymous access by default.)

10.In the Web Site Access Permissions box, set the permissions for thehome directory.

11.Click Next , and then click Finish .

8)How 2 register a website on search engine:-

Step 1) Registering a domain name:

The first step to setting up any website is to figure out what you would liketo call it. When naming a website a tip that can help you get your websiteranked highly in the search engines is to try to include targeted keywords inyour domain name. If you are setting up a website to sell furniture try toregister a domain name that includes the keyword "furniture". Searchengines tend to give greater importance to domains that contain a searcherskeywords. It doesn't mean that you won't be able to get a non keywordeddomain ranked well in the search engines but a keyworded domain will beeasier to get ranked in the search engines then a domain that doesn't containany keywords. If your website isn't going to rely on search engine rankingsor is in a non competitive niche then getting a keyworded domain is not anissue.

There are lots of domain registrars available for use on the Internet and youwill have to do a search to find one that looks reputable and is wellestablished.

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If you would like to setup a personal site then free web hosting sites likeBlogger.com and WordPress.org can be a good option as they will let youregister a free domain name when you create an account with them.

Step 2) Find a place to host your website:

After you have decided on your domain name and registered it you will needa web server to host your website on. There are again lots of companies thatwill host your website for you for a small monthly fee. This particular site ishosted using services from HostGator and has found them quite good.

You can also setup your own web server if you have the technical know how but these days being as there are a lot of companies offering inexpensivehosting options and the overhead that goes into running your web server

there isn't much reason not to farm out the hosting work to a company thatspecializes in web hosting.

Step 3) Designing your website:

There are many different options when it comes to website design. If youhave the technical know how you can do it yourself but if you require helpyou can acquire the services of a professional website design company thatwill create a website for you for a fee.

Once your website has been designed you just need to upload the files toyour web server to make it available for the world to view.

Step 4) Marketing your website on the Internet:

After you have designed and uploaded your website to your web server space the next step is to start getting the word out about your website. If youwant to get your website ranked well in the search engines you will need toengage in a process called Search Engine Optimisation which is the processof choosing the keywords you would like to rank on and then implementing

those keywords into your websites text in a meaningful for the searchengines to discover. If you know what you are doing you an embark on this

process yourself or there are companies that are skilled in Search EngineMarketing and can help you get your website ranked highly in the searchengines.

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9)Email hosting services:--

An e-mail hosting service is an Internet hosting service that runs e-mail servers.

Email hosting is a very valuable resource these days, with the explosion indemand for email services and the huge number of people who send andreceive email messages every day. Email hosting can be a very attractiveoption for companies, especially as a means of gaining new customers.

Companies that offer email hosting necessarily have large server resources.Here’s why: Email hosting is potentially a very large enterprise, dependingon how many bells and whistles are offered. Email hosting means that acompany offers to perform email functions for customers. These functions

can be as basic as send and receive and as complicated as database processing and global searching.

E-mail hosting services usually offer premium e-mail at a cost as opposed toadvertising supported free e-mail or free webmail. E-mail hosting servicesthus differ from typical end-user e-mail providers such as webmail sites.They cater mostly to demanding e-mail users and Small and Mid Size(SME ) businesses, while larger enterprises usually run their own e-mailhosting service. E-mail hosting providers allow for premium e-mail servicesalong with custom configurations and large number of accounts. In addition,hosting providers manage user's own domain name , including any e-mailauthentication scheme that the domain owner wishes to enforce in order toconvey the meaning that using a specific domain name identifies andqualifies e-mail senders.

Most e-mail hosting providers offer advanced premium e-mail solutionshosted on dedicated custom e-mail platforms. The technology and offeringsof different e-mail hosting providers can therefore vary with different needs.E-mail offered by most webhosting companies is usually more basicstandardized POP3 based e-mail and webmail based on open sourcewebmail applications like Horde or SquirrelMail . Almost all webhosting

providers offer standard.

Major functions are:-

i)Global searching

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ii)Chatting

iii)send and receive

iv)Database processing

v)reliability

vi)security

10)Types of search engines:--

i)Spider based:-

A Web crawler is a computer program that browses the World Wide Web in a methodical, automated manner or in an orderly fashion. Other terms for Web crawlers are ants , automatic indexers , bots , [1] or Web spiders , Webrobots , or—especially in the FOAF community— Web scutters [2].

This process is called Web crawling or spidering . Many sites, in particular search engines , use spidering as a means of providing up-to-date data. Webcrawlers are mainly used to create a copy of all the visited pages for later

processing by a search engine that will index the downloaded pages to provide fast searches. Crawlers can also be used for automating maintenancetasks on a Web site, such as checking links or validating HTML code. Also,crawlers can be used to gather specific types of information from Web

pages, such as harvesting e-mail addresses (usually for spam ).

A Web crawler is one type of bot , or software agent. In general, it starts witha list of URLs to visit, called the seeds . As the crawler visits these URLs, itidentifies all the hyperlinks in the page and adds them to the list of URLs tovisit, called the crawl frontier . URLs from the frontier are recursively visited

according to a set of policies.

WEB CROWLER ARCHITECTURE:-

A crawler must not only have a good crawling strategy, as noted in the previous sections, but it should also have a highly optimized architecture.

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Shkapenyuk and Suel [34] noted that: "While it is fairly easy to build a slowcrawler that downloads a few pages per second for a short period of time,

building a high-performance system that can download hundreds of millionsof pages over several weeks presents a number of challenges in systemdesign, I/O and network efficiency, and robustness and manageability."

Web crawlers are a central part of search engines, and details on their algorithms and architecture are kept as business secrets. When crawler designs are published, there is often an important lack of detail that preventsothers from reproducing the work. There are also emerging concerns about"search engine spamming ", which prevent major search engines from

publishing their ranking algorithms.

Examples of Web crawlers:-

Yahoo! Slurp is the name of the Yahoo Search crawler.Msnbot is the name of Microsoft's Bing webcrawler.FAST Crawler [35] is a distributed crawler, used by Fast Search &

Transfer , and a general description of its architecture is available. [citation needed ]

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Googlebot [33] is described in some detail, but the reference is only aboutan early version of its architecture, which was based in C++ and Python . Thecrawler was integrated with the indexing process, because text parsing wasdone for full-text indexing and also for URL extraction. There is a URLserver that sends lists of URLs to be fetched by several crawling processes.During parsing, the URLs found were passed to a URL server that checkedif the URL have been previously seen. If not, the URL was added to thequeue of the URL server.

Methabot is a scriptable web crawler written in C, released under theISC license .

80legs is a commercial web crawler that is offered through asoftware as a service model.

ii)Directory based/Human based:-A human search engine is a search engine that uses human participation tofilter the search results and assist users in clarifying their search request. Thegoal is to provide users with a limited number of relevant results, as opposedto traditional search engines that often return a large number of results thatmay or may not be relevant.

Examples of human search engines include Jumper 2.0 , Sproose , NiteCo [1] ,ChaCha Search , Mahalo.com , Isawiki and the now defunct NowNow from

Amazon.com .

iii)Hybrid search engine:-

A hybrid search engine (HSE ) is a type of computer search engine thatuses different types of data with or without ontologies to produce thealgorithmically generated results based on web crawling . Previous types of search engines only use text to generate their results.

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