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LOGO
Instructor: Ch. Bilal Ahmad Khan
Internet and Cyberspace
History of Communication and Internet
Slide Rule-1621
Mechanical Adding Machine -1642
Ada Lovelace - 1843
Telegraph Message Machine - 1844
First Telephone - 1876
History of Communication and Internet
First Radio Signal - 1895First Radio Broadcast -1907
First ATM - 1963
Internet Operation
Internet Operation
Applications of Internet
Data Transmission Capacity
Bandwidth, or channel capacity, is an expression of how much data - text, voice, video, and so on - can be sent through a communications channel in a given amount of time
The type of data transmission that allows only one signal at a time is called baseband transmission
several signals can be transmitted at once, it’s called broadband transmission
Broadband - very high speed - connections Fiber Optics, DSL, cable, and satellite and other
wireless connections
Physical Connection for Internet
Wired Dialup ISDN DSL T1
Wireless Through Air Link (e.g. PTCL EVO, Wateen,
Wi-Tribe) Satellite
Data Transmission Speed
bps Bits per second Eight bits equals one character, such as A, 3, or # Kbps
Kbps kilobits per second 1 thousand bits per second
Mbps megabits per second 1 million bits per second
Gbps gigabits per second 1 billion bits per second
Connecting with Internet
Narrowband Dialup Connections
Connecting with Modem Modems and Call Waiting
Source: Using Information Technology by William and Sawyer
Connecting with Internet
High Speed Phone Lines ISDN (Integrated Services Digital Network)
consists of hardware and software that allow voice, video, and data to be communicated over traditional copper-wire telephone lines
DSL (digital subscriber line) uses regular phone lines, a DSL modem, and special technology to transmit data in megabitsper second
T1 line, essentially a traditional trunk line that carries 24 normal telephone circuits and has a transmission rate of 1.5 to 6 Mbps
Connecting the Internet
Source: Using Information Technology by William and Sawyer
Wireless Connections
Satellite Communications Communications satellite, a space station that transmits radio
waves called microwaves from earth-based stations Wi-fi
802.11 standards by IEEE of wireless transmissions Transmission of data at up to 54 Mbps 300-500 feet covered by access point
2G Used for mobile communications
3G High-speed wireless technology that does not need access
points because it uses the existing cell phone system
Working of Internet
Client computer requesting data or services Normally a computer in front of user
Server Is a central computer supplying data or
services requested of it Also known as host computer
Working of Internet
Point of Presence Local access point to the internet A collection of modems and other equipment in a local
area POP acts as a local gateway to the ISP’s network
Network Access Point A routing computer at a point on the internet where
several connections come together Owned by a network service provider
Internet Backbone High-speed, high-capacity transmission lines that use
the newest communications technology to transmit data across the internet
Working of Internet
Working of Internet
Protocols Set of rules, that computers must follow to transmit data
electronically The protocol that enables all computers to use data
transmitted on the internet is called Transmission Control Protocol/Internet Protocol, or TCP/IP,
Packets TCP/IP breaks the data in a message into separate
packets Fixed-length blocks of data for transmission
IP Address Internet Protocol (IP) address uniquely identifies every
computer and device connected to the internet
World Wide Web
Design and Develop Web Site
Choose the name of website
Buy domain name with Web Host
Web Host provides web space
Upload files to the web server
Write the URL in the web browser
Browse the website
Client Server
DatabaseSend
RequestRequest
Data
Fetch
DataFetch
Reply
World Wide Web
Design and Develop Database
Design and Develop Web Site
Choose the name of website
Buy domain name with Web Host
Web Host provides web space
Upload files to the web server
Write the URL in the web browser
Browse the website
Client Server
Database
Data
SQL Query
Send
RequestRequest
Data
Fetch
DataFetch
Reply
World Wide Web
URL URL (Uniform Resource Locator) is a string of
characters that points to a specific piece of information anywhere on the web
World Wide Web
Protocol (http://) HyperText Transfer Protocol (HTTP) , the communications rules
that allow browsers to connect with web servers Another protocol is ftp://
Domain Name Domain is simply a location on the internet, the particular web
server
Directory Name The directory name is the name on the server for the directory,
or folder, from which your browser needs to pull the file
File Name The file is the particular page or document that you are seeking
Search Engines
Search services are organizations that maintain databases accessible through websites to help you find information on the internet
Search engines are programs that enable you to ask questions or use keywords to help locate information on the web
Spiders - also known as crawlers, bots (for “robots”), or agents – that crawl through the World Wide Web, following links from one web page to another and indexing the words on that site
Search Engines
Individual Search Engines Compiles its own searchable database on the web Hits are defined as the sites that a search engine
returns after running a keyword search Examples are Bing, Yahoo, Google etc
Subject Directories Created and maintained by human editors, not
electronic spiders, and allows you to search for information by selecting lists of categories or topics
Examples are Galaxy, Google Directory, LookSmart, Open Directory Project, and Yahoo! Directory
Search Engines
MetaSearch Engines Allows you to search several search
engines simultaneously Examples are Clusty, Dogpile, Mamma,
MetaCrawler, and Webcrawler etc Specialized Search Engine
Help locate specialized subject matter, such as material about movies, health, and jobs
Examples are imdb, expedia, rozee, career etc
Emails and More Modes of Communication
Simple Mail Transfer Protocol Post Office Protocol Version 3 Internet Message Access Protocol
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