EContent_11_2022_12_09_22_13_58_UnitISRPpdf__2022_10_11_14_14_42.pdf

Department of
Computer
Engineering
Diploma Studies
Surabhi R Palkar
Assistant Professor
Unit No. 1
Internet and WWW
Basics of Web Design
(09CE2102)

Unit 1
01
02
04
05
06
✓ Introduction to Internet
Prof. Surabhi R Palkar
Basics of Web Design (09CE2102)

01
02
04
05
06

01
02
04
05
06
✓ https://www.youtube.com/watch?v=jKA5hz3dV-g&feature=youtu.be

06
✓ Most people think the Internet is a set of services such as Facebook,
Snapchat, Instagram, Gmail, etc.
✓ But, it is a global computer communication system that has made all the
services possible.
✓ Internet is a network of networks.
✓ A network is defined as a group of two or more computers / electronic
devices which are linked together.

06
✓ WWW (World Wide Web)
✓ The leading information retrieval service of the Internet.
✓ The Web gives users access to a vast array of documents that are
connected to each other by means of hypertext or hypermedia links—
i.e., hyperlinks.
https://www.youtube.com/watch?v=lYUMqsqNAdM

06
✓ WWW (World Wide Web)
✓ The development of the World Wide Web was begun in 1989 by Tim
Berners-Lee and his colleagues at CERN, an international scientific
organization based in Geneva, Switzerland.
✓ In 1990, first website was published which was info.fern.ch
✓ WWW was made available publically in 1991.
✓ In 1993, it was made free globally.

06
✓ Web Browser

06
✓ Web Browser
✓ The Web operates within the Internet’s basic client server format.
✓ Servers are computer programs that store and transmit documents to
other computers on the network when asked to, while clients are
programs that request documents from a server as the user asks for
them.
✓ Browser software allows users to view the retrieved documents.

06
✓ Web Server
✓ A web server is computer software and underlying hardware that
accepts requests via HTTP.

06
✓ Web Page
✓A web page is a hypertext document on the World
Wide Web.
✓ Web pages are delivered by a web
server to the user and displayed in
a web browser.
✓A website consists of many web
pages linked together under a
common domain name.

06
✓ URL
(Uniform Resource Locator)
✓ How does a browser know where to find information?
✓ A user must specify the correct web server and a web page on the
server. To do so, a user enters a Uniform Resource Locator (URL).
✓ A URL is a string of characters divided into several parts by
punctuation characters

06
✓ Domain Name
✓A domain name is essential for website. (name and extension).
✓A web browser needs a domain name to direct you to a website.
✓An organization called ICANN (Internet Corporation for Assigned
Names and Numbers).
✓ICANN specifies which domain name extensions are available and keeps
a database of where the domain names point to.

06
✓ Domain Name
✓ Without a domain name, anyone who wanted to visit your website would
have to enter the full IP address.
✓ But the problem is that an IP address is difficult for people to memorize.
✓ Different Top level domains - .com .org .net .edu
.in .gov co.in
https://www.youtube.com/watch?v=JkEYOt08-rU

06
✓ Domain Name
https://www.youtube.com/watch?v=72snZctFFtA

06
✓ Domain Name
✓Top-Level Domain Names (TLDs)
A top-level domain (TLD) identifies the rightmost part of the domain
name. A TLD is either a generic top-level domain, such as com for
commercial, or a country code top-level domain, such as fr for France.

06
✓ Domain Name

06
✓ Domain Name
✓ Country Code Top-Level Domain Names
➢ Two-character country codes have also been assigned as top-level domain names.
➢ These were originally intended to be meaningful and relate the domain name country code
to the geographical location of the individual or organization that registered the name.

06
✓ Domain Name
The DNS associates domain names with IP addresses. The following happens each time
a new URL is typed into a Web browser:
1. The DNS is accessed.
2. The corresponding IP address is obtained and returned to the Web browser.
3. The Web browser sends an HTTP request to the destination computer with the
corresponding IP address.
4. The HTTP request is received by the Web server.
5. The necessary files are located and sent by HTTP responses to the Web browser.
6. The Web browser renders and displays the Web page and associated files.

06
✓ Domain Name System Working:
1. DNS Resolver: When you type in google.com in your web browser and if your web browser or
operating system cannot find IP address in its own cache memory, it will send a query to next level
to what is called resolver server. Resolver server is basically your ISP or Internet service provider,
so when resolver receives this query, it will check its own cache memory to find an IP address for
google.com, and if it cannot find it it will send query to next level which is root server.
2. Root Server: The root servers are the top most server in the DNS hierarchy. There are 13 sets
of these root servers from a.root-servers.net to m.root-servers.net and they are strategically placed
around world, and they are operated by 12 different organizations and each set of these root
servers has their own unique IP address. So when root server receives query for IP address for
google.com, root server is not going to know what IP address is, but root server does know where
to send resolver to help it find IP address. So root server will direct resolver to TLD or top-level
domain server for that domain.

06
✓ Domain Name System Working:
3. Top Level Domain Name Server: The top-level domain server stores address information for
top-level domains such as .com and .net, .org, and so on. So when a TLD server receives query for
IP address, TLD server is not going to know what IP addresses. So the TLD will direct resolver to
next and final level, which are authoritative name servers. So once again the resolver will now ask
authoritative name server for IP address.
4. Root Server: Authoritative name server or servers are responsible for knowing everything
about domain which includes IP address. They are final authority. So when the authoritative name
server receives query from resolver, name server will respond with IP address for google.com.
And finally, resolver will tell your computer IP address and then your computer can now retrieve
google web page.
It is important to note that once resolver receives IP address, it will store it in its cache
memory in case it receives another query for that website. So it does not have to go
through all those steps again.

06
✓ Search Engines
A search engine is a software program that helps people find the information they are
looking for online using keywords or phrases.

06
✓ IP Address
✓ Every computer on the Internet has a unique address, called an IP address, that
distinguishes it from other computers on the Internet.
✓ An IP address acts as an identifier for a specific device on a particular network.
✓IP addresses are managed and allocated by the Internet Assigned Numbers
Authority (IANA).
✓ Currently, there are two versions of IP addresses exist: IPv4 (Internet Protocol
Version 4) and IPv6 (Internet Protocol Version 6).

06
✓ IPv4
✓IPv4 is an IP version widely used to identify devices on a network using an
addressing system.
✓It was the first version of IP deployed for production in the ARPANET in
1983.
✓It uses a 32-bit address scheme to store 2^32 addresses which is more than 4
billion addresses.
✓It is considered the primary Internet Protocol and carries 94% of Internet
traffic.
✓IPv4 address has two parts that identify a specific computer.
✓One part to identify the network where that computer resides and a second part
to pinpoint the specific computer or host within that network.

06
✓ IPv4 Classful Addressing (Addressing scheme)

06
✓ IPv6
✓This new IP address version is being deployed to fulfil the need for more
Internet addresses.
✓It was aimed to resolve issues which are associated with IPv4. With 128-bit
address space, it allows 340 undecillion unique address space. IPv6 also called
IPng (Internet Protocol next generation).
✓An IPv6 address has three parts.
✓A global prefix to identify the network, a subnet to identify the location
within the network, and the interface ID to identify the specific computer or
host.

06
✓ IPv6 Addressing Scheme
✓ The lower 16 bits are used for subnets on an internal networks, and are
controlled by a network administrator.
✓ The upper 48 bits are used for the global network addresses and are for routing
over the internet.

06
✓ IPv4

06
✓Protocols
✓ Protocols are rules that describe how clients and servers communicate with
each other over a network.
✓ There is no single protocol that makes the Internet and Web work—a
number of protocols with specific functions are needed.

06
✓ HTTP (Hypertext Transfer Protocol)
✓HTTP is a set of rules for exchanging files such as text, graphic images,
sound,
video, and other multimedia files on the Web.
✓Web browsers and Web servers usually use this protocol. When the user of a
Web browser requests a file by typing a Web site address or clicking a
hyperlink, the browser builds an HTTP request and sends it to the server.
✓The Web server in the destination machine receives the request, does any
necessary processing, and responds with the requested file and any
associated media files.

06
✓ HTTP vs HTTPS

06
✓FTP (File Transfer Protocol)
✓ File Transfer Protocol (FTP) is a set of rules that allow files to be
exchanged between computers on the Internet.
✓ Unlike HTTP, which is used by Web browsers to request Web pages and
their associated files in order to display a Web page, FTP is used simply to
move files from one computer to another.
✓ Web developers commonly use FTP to transfer Web page files from their
computers to Web servers.
✓ FTP is also commonly used to download programs and files from other
servers to individual computers.

06
✓FTP (File Transfer Protocol)
✓ We can use FTP to access a remote computer on the network to get or
receive files, or to put or send files.
✓ A computer on the Internet that offers FTP access is said to be an FTP host
or FTP server.

06
✓ Why FTP?
✓ Although transferring files from one system to another is very
simple and straightforward, but sometimes it can 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 different directory structures.
✓ FTP protocol overcomes these problems by establishing two
connections between hosts.
✓ One connection is used for data transfer, and another connection
is used for the control connection.

06
✓FTP mechanism
✓ Control Connection: The control connection uses very simple rules for
communication. Through control connection, we can transfer a line of
command or line of response at a time. The control connection is made
between the control processes. The control connection remains connected
during the entire interactive FTP session.
✓ Data Connection: The Data Connection uses very complex rules as data types
may vary. The data connection is made between data transfer processes. The
data connection opens when a command comes for transferring the files and
closes when the file is transferred.

06
✓ FTP mechanism

06
✓Transmission Control Protocol/Internet Protocol
(TCP/IP)
✓ Transmission Control Protocol/Internet Protocol (TCP/IP) has been adopted as
the official communication protocol of the Internet.
✓ TCP and IP have different functions that work together to ensure reliable
communication over the Internet.
✓ TCP starts by breaking files and messages into individual units called packets.
These packets contain information such as the destination, source, sequence
number, and checksum values used to verify the integrity of the data.

06
✓ TCP/IP
✓TCP is used together with IP to transmit files efficiently over the Internet.
✓IP takes over after TCP creates the packets, using IP addressing to send each
packet over the Internet using the best path at the particular time.
✓When the destination address is reached, TCP verifies the integrity of each
packet using the checksum, requests a resend if a packet is damaged, and
reassembles the file or message from the multiple packets.

EContent_11_2022_12_09_22_13_58_UnitISRPpdf__2022_10_11_14_14_42.pdf

Recommended

Recommended

More Related Content

Similar to EContent_11_2022_12_09_22_13_58_UnitISRPpdf__2022_10_11_14_14_42.pdf

Similar to EContent_11_2022_12_09_22_13_58_UnitISRPpdf__2022_10_11_14_14_42.pdf (20)

Recently uploaded

Recently uploaded (20)

EContent_11_2022_12_09_22_13_58_UnitISRPpdf__2022_10_11_14_14_42.pdf