Network, Internet and Network, Internet and World Wide WebWorld Wide Web

Essential Concepts Essential Concepts

Natalia Mosina - 2005 Natalia Mosina - 2005

Network• Most people work in a network

environment

A network is a collection of computers connected together with special hardware and software to manage it.

LAN – local area network (small area)

WAN – wide area network (long distances)

From LAN to WAN

(a) Home Network

(b) Local Area Network

From LAN to WAN (continued)

(c) Wide Area Network

The Internet and How We Connect to It Using an ISP

• Explain what the Internet is

Internet

• The Internet is a worldwide collection of computer networks

• The Internet is a network of networks that connects users in every country in the world. There are currently over one billion Internet users worldwide.

The Internet and How We Connect to It Using an ISP

• Define an Internet Service Provider and its purpose

ISP

• An ISP is a company that provides the connections and support to access the Internet.

• It can also provide additional services such as Email and web hosting.

• ISPs are essential to gaining access to the Internet

• ISPs range in size from small to very large and differ in terms of the area they service.

• ISPs also differ in the types of connection technologies and speeds they offer

The Internet and How We Connect to It Using an ISP

• Describe how you connect to the Internet through the ISP and the ISP’s relationship to the Internet

PoP• A POP is the connection point between the

ISP's network and the particular geographical region that the POP is servicing.

• An ISP may have many POPs depending on its size and the area it services

• The Internet is made up of very high-speed data links that interconnect ISP POPs and ISPs to each other.

• These interconnections are part of the very large, high capacity network known as the Internet Backbone.

The Internet and How We Connect to It Using an ISP

• ISPs provide a variety of ways to connect to the Internet, depending on location and desired connection speed.

• The choice of Internet access technologies depends on availability, cost, access device used, media used and the speed of the connection.

The Internet and How We Connect to It Using an ISP

• The contract with the ISP determines the type and level of services that are available.

How Information is Sent When Using an ISP

• Define and explain that the most important protocol of the Internet is the Internet Protocol (IP).

The World Wide Web (www)The World Wide Web (www)• The Web presents information through multimedia formats:

graphics, sound, animation, and video.• The Web uses several tools to provide a visual layout:

• Hypertext links• Browser software• Code structure

• The Web resembles an electronic library – each location or site is like a book.

• These books are created using Hypertext Markup Language (HTML).

• These materials, along with interactive objects such as Java, JavaScript, and VBScript adds functionality to web pages.

Client vs. Server

• When you connect to Internet to become part of the web, your computer becomes a Web client in a worldwide client/server network.

• Web browser is the software that you run on your computer to make it work as a Web client.

A Client/Server Model

• A server (Web server or Web site) is any computer that stores documents and furnishes them upon request

• A client is any computer that requests services (requests and then displays documents )

• Every client must be able to display every document from every server and does so through a browser (e.g., Netscape or Internet Explorer)

•

Connecting to the InternetConnecting to the Internet

• Elements required to connect to the Internet:• Computer, WebTV, mobile phone, or Personal Digital Assistant

(PDA)• Dial-up modem, digital subscriber line (DSL) modem, or cable

modem• Operating System: Windows 95/98/Me, Windows NT/2000/XP,

Linux/UNIX, Macintosh• Telecommunications/Client Software: Web browser, e-mail or news

client programs• Internet Connection (telephone line or cable connection): dial-up or

direct connection to an Internet Service Provider (ISP) or Value-Added Network (VAN) such as America Online (AOL) or Microsoft Network (MSN)

• Internet Addresses: Web addresses (e.g., www.msn.com), e-mail addresses (e.g., student@class.com), server addresses (e.g., ss1.ProSoftTraining)

Connecting to the Internet

• At Work or School – Via a Local Area Network

• At Home – Traditional Modem (56Kbps) – Cable Modem

• Uses TV cable • Requires network card

– DSL Modem • Voice and data on the same line • Requires network card

•

Connection TypesConnection Types

• Dial-Up Connection– Use a modem to access the Internet on a per-use basis. The user

accesses the ISP via phone line and when finished, disconnects from the ISP.

– The speed of access is determined by the speed of your modem.

– To gain faster access, you can install an Integrated Services Digital Network (ISDN) line, which is a digital phone line.

• Direct Connection– Provide continuous access to the Internet

– Convenient and fast and capable of handling high bandwidth

Domain Name System (DNS)Domain Name System (DNS)

• To access a website, you must enter the address of the web server in your browser.

• The IP address (the dotted quad) is one way to identify the server; however, most users prefer to use domain names because they are easier to remember.

• The Domain Name System (DNS) translates IP addresses into easily recognizable names.

• Examples: IP address: 72.64.56.86

Domain name: www.microsoft.com

Domain NamesDomain Names

• Each domain name is unique. It consists of letters and numbers separated by dots and includes two or more words (labels).

• The last label in a domain name is usually a two- or three-letter code called a top-level domain.

• Example: www.microsoft.comServer (Host) Name Registered Company Domain Category

Domain Name (Top-Level Domain)

Domain Name SyntaxDomain Name Syntax

• A domain name, read left to right, specifies general divisions, then specific companies, and individual computers (web servers or e-mail servers)

com = a commercial site

microsoft = the name registered by the company

www = the name of the web server at the company, also called the web site host

Domain NamesDomain Names

• A fully qualified domain name (FQDN) is the complete domain name of an Internet computer. It provides enough information to covert the domain name to an IP address.

• Top-Level Domains.com = commercial or company sites.edu = educational institutions .gov = U. S. civilian government.mil = U. S. military.org = organizations.net = network sites, including commercial ISPs.int = international organizations

• Two-Letter Country Codes – categorize domains by country or region. For example: us = United States

au = Australia

Registering a Domain NameRegistering a Domain Name

• To register a domain name, your Internet Service Provider (ISP), your employer, or you must make a formal request to a domain name registrar.

• In the U. S., the Internet Corporation for Assigned Names and Numbers (ICANN) verifies which companies can serve as domain name registrars. The ICANN is responsible for accrediting its registrars.

• Each country has a different process for registering domain names.

• Domain name registrars activate domain names using a first-come, first-served basis.

• If your domain name choice is available, you will receive notice via standard and electronic mail.

• Network Solutions (www.networksolutions.com) was selected as one of the original five registrars.

• Registrars provide the following services:– Domain name registration

– Registration service forms for domain name transfers, modifications, etc.

– Resource links for payment options and policies.

– Search capabilities for registered domain names, host IP addresses, and last name/first name queries using WHOIS (an internet utility primarily used to query databases to determine registered hosts)

Registering a Domain NameRegistering a Domain Name

Uniform Resource Locators (URL)Uniform Resource Locators (URL)

• A URL is a text string that supplies an internet or intranet address and the method by which the address can be accessed.

• URLs start with the http:// prefix which identifies them as web pages using the Hypertext Transfer Protocol.

• For example, if you enter the following web address:

http://www.microsoft.com

The URL will access a web page because it begins with http. It then contacts the web server and domain named www.icann.org. It will locate a file on the server.

Uniform Resource Locator (URL)Uniform Resource Locator (URL)

http://www.prenhall.com/reed/index.htmlhttp://www.prenhall.com/reed/index.html

Protocol (means of access)

Web Server

Directory where the Page is stored

Name of the page Or document

URL URL

Top-level domains include “edu,” “gov,” and Top-level domains include “edu,” “gov,” and “org,” but “com” is most common “org,” but “com” is most common

Examples: Examples: www.microsoft.comwww.microsoft.com www.nba.comwww.nba.com www.whitehouse.govwww.whitehouse.gov www.miami.eduwww.miami.edu

CookiesCookies

• Cookies are small text files placed on a website visitor’s computer so website managers can customize their site to a visitor’s preferences. They also gain information about visitors that could be used for marketing needs.

• Unless you register with a site, cookies do not have access to any personal information about you.

• The text is entered into the memory of the browser. The browser in turn stores the cookie information on the hard drive so when the browser is closed and reopened at a later date the cookie information is still available.

CookiesCookies

• Cookies are small text files placed on a website visitor’s computer so website managers can customize their site to a visitor’s preferences. They also gain information about visitors that could be used for marketing needs.

• Unless you register with a site, cookies do not have access to any personal information about you.

• The text is entered into the memory of the browser. The browser in turn stores the cookie information on the hard drive so when the browser is closed and reopened at a later date the cookie information is still available.

Web sites use cookies for several Web sites use cookies for several

different reasons:different reasons:

• To collect demographic information about who is visiting the Web site. Sites often use this information to track how often visitors come to the site and how long they remain on the site.

• To personalize the user's experience on the Web site. Cookies can help store personal information about you so that when you return to the site you have a more personalized experience.

Web sites use cookies for several Web sites use cookies for several different reasons:different reasons:

If you have ever returned to a site and have seen your name mysteriously appear on the screen, it is because on a previous visit you gave your name to the site and it was stored in a cookie so that when you returned you would be greeted with a personal message.

A good example of this is the way some online shopping sites will make recommendations to you based on previous purchases. The server keeps track of what you purchase and what items you search for and stores that information in cookies.

Web sites use cookies for several Web sites use cookies for several different reasons:different reasons:

• To monitor advertisements. Web sites will often use cookies to keep track of what ads it lets you see and how often you see ads.

• To collect demographic information about who is visiting the Web site. Sites often use this information to track how often visitors come to the site and how long they remain on the site.

• To personalize the user's experience on the Web site. Cookies can help store personal information about you so that when you return to the site you have a more personalized experience.

Web sites use cookies for several Web sites use cookies for several different reasons:different reasons:

If you have ever returned to a site and have seen your name mysteriously appear on the screen, it is because on a previous visit you gave your name to the site and it was stored in a cookie so that when you returned you would be greeted with a personal message.

A good example of this is the way some online shopping sites will make recommendations to you based on previous purchases. The server keeps track of what you purchase and what items you search for and stores that information in cookies.

Web sites use cookies for several Web sites use cookies for several different reasons:different reasons:

• To monitor advertisements. Web sites will often use cookies to keep track of what ads it lets you see and how often you see ads.

CookiesCookies

• Cookies do not act maliciously on computer systems. They are merely text files that can be deleted at any time - they are not plug ins nor are they programs.

• Cookies cannot be used to spread viruses and they cannot access your hard drive. This does not mean that cookies are not relevant to a user's privacy and anonymity on the Internet.

• Cookies cannot read your hard drive to find out information about you; however, any personal information that you give to a Web site, including credit card information, will most likely be stored in a cookie unless you have turned off the cookie feature in your browser. In only this way are cookies a threat to privacy.

CookiesCookies

• The cookie will only contain information that you freely provide to a Web site.

Cookies have six parameters that Cookies have six parameters that

can be passed to them:can be passed to them: • The name of the cookie. • The value of the cookie. • The expiration date of the cookie - this determines

how long the cookie will remain active in your browser.

• The path the cookie is valid for - this sets the URL path the cookie us valid in. Web pages outside of that path cannot use the cookie.

Cookies have six parameters that Cookies have six parameters that can be passed to them:can be passed to them:

• The domain the cookie is valid for - this takes the path parameter one step further. This makes the cookie accessible to pages on any of the servers when a site uses multiple servers in a domain.

• The need for a secure connection - this indicates that the cookie can only be used under a secure server condition, such as a site using SSL.