Chapter 2 - How The Web Works

Question 1

What is the internet?

Answer 1

It’s a network of interconnected computers - no company owns the internet. it’s a cooperative effort governed by a system of standards and rules. the purpose of connecting computers together, of course, is to share information

Question 2

What is the web?

Answer 2

One of the many ways that information can be shared over the internet. Some of the other ways include email, file transfer, and many more specialized modes upon which the internet is built - all these methods (incl. the web) are known as protocols

Question 3

What is unique about the web?

Answer 3

It is unique in that it allows documents to be linked to one another using hypertext links - thus forming a huge “web” of connected of information. The web uses a protocol called HTTP (HyperText Transfer Protocol)

Question 4

What do you call the computers that make up the internet?

Answer 4

Servers - because they “serve up” information on request. Btw, the server is the software, not the actual computer

Question 5

What is the role of the server software?

Answer 5

To wait for a request for information, then retrieve and send that information back as quickly as possible

Question 6

What other name can you call web servers?

Answer 6

HTTP Servers

Question 7

For a computer to be part of the web, it must be running a web server software that allows it to handle HyperText Transfer Protocol Transactions. True or False?

Answer 7

True… it’s the server software that makes it all happen, there’s nothing special about the computers themselves - from a high-powered unix machine to a humble personal computer

Question 8

Is the server different from a desktop pc? Discuss…

Answer 8

Almost any computer that meets the minimum hardware requirements (processor speed, memory, storage capacity) can run a server operating system, that alone does not make a desktop computer a true server. The technologies behind them are engineered for different purposes.

A Desktop computer - typically runs a user-friendly operating system and desktop applications to facilitate desktop-oriented tasks while a server manages all network resources (they’re often dedicated) - Servers are designed to manage, store, send and process data 24-hours/day and it has to be more reliable than desktop and it also has a variety of features and hardware not typically found in a desktop computer.

Server Hardware: Form Factor: for some businesses, the best choice is a dedicated entry-level server in a tower configuration. Processor: Choose a server-specific processor to boost performance & data throughout. Memory: Buys as much memory as you can afford and look for expansion slots for future upgrades. Storage: Look for SATA OR SCSI hard disks, not IDE

SOS (Server Operating System): Is the software platform on top of which other programs will run (not a easy task) - it will depend on what the server will be used for.

Overall - for an infrequently used server… a build from an old desktop computer could work. But for a business, it is probably best to buy a computer that is ready-made to be a dedicated software than one which began life as a desktop computer.

Question 9

Name some of the server software options out there

Answer 9

Apache - Open Source Software. Freely available for unix-based computers and comes installed on MACS running MAC OS X
Microsoft Internet Information Services (IIS) - Microsoft family of server solutions

Question 10

Every computer and device connected to the internet is assigned a unique numeric IP address (IP = Internet Protocol). True or False

Answer 10

True

Question 11

What is the Domain Name System

Answer 11

Otherwise known as DNS… was developed to help us refer to an IP address or Server by it’s domain name. For example, IP #208.201.239.100 is Oreilly.com. The numeric IP address is useful for computer software, while the domain name is more accessible to humans

Question 12

Matching the text domain names to their respective numeric IP addresses is done by

Answer 12

the DNS Server

Question 13

Is it possible to configure your web server to host more than one domain name?

Answer 13

Yes - multiple domain names can be mapped to a sing IP address

Question 14

What is an open source software?

Answer 14

software that is developed as a collaborative effort with the intent to make its source code available to other programmers for use & configuration - they’re usually free

Question 15

Briefly enumerate the history of the web…

Answer 15

The web was born in a particle physics lab (CERN) in Geneva, Switzerland in 1989

By a computer specialist named Tim Berners-Lee as a system info management system that used hypertext process to link related documents over a network.

He & his partner, Robert Cailliau, created a prototype and released it for review

For the first several years, web pages were text only - in 1992, the world had only about 50 web servers total

In 1992, the first graphical browser (NCSA Mosaic) was introduced, and the web broke out of the realm of scientific research into mass media

Question 16

Discuss IP Addresses

Answer 16

The IANA assigns IP numbers in bundles, the last bundle of IP addresses were handed down on Feb 3, 2011. No more ###.###.###.###- IPv4 is gone - it’s only able to generate about 4.3 billion unique addresses - seemed like a lot when the internet experiment was conceived in 1977 (didn’t anticipate everything on the planet would be connected to the internet at some point) - The solution is IPv6 - allows for trillions & trillions of unique IP numbers but incompatible IPv4-based network - so v6 will operate in parallel to the one we have today and then v4 will be phased out, but that would probably take decades

Question 17

The software that does the requesting is called?

Answer 17

Client

Question 18

List examples of clients

Answer 18

desktop browsers, mobile browsers, assistive technologies to access documents on the web - the server returns the documents for the browser (also referred to as the user agent in tech circles)

Question 19

Discuss intranets vs extranets

Answer 19

networks used to exchange information just within an organization are called intranets - they function like ordinary websites, but they use special security devices known as firewalls that prevent the outside world from seeing them . An extranet is similar only it allows access to select users outside of the company.

Question 20

Server-Side vs Client-Side

Answer 20

These terms are used to indicate which machine is doing the processing - Client side applications run on the user’s machine, while server-side applications use the processing power of the server computer

Question 21

Web Address (URL)? - Discuss

Answer 21

Every page or resource on the web has it’s own address or URL (Uniform Resource Locator)

Question 22

Highlight & Discuss the parts of a URL

Answer 22

http: //www.example.com/2011/samples/first.html
http: // - first thing the URL does is to define the protocol that will be used for that particular transaction - http lets the server know to use Hypertext Transfer Protocol or “web mode”
www. example.com - the next is the name of the website (it’s domain name)

/2012/samples/first.html - this is the absolute path through directories on the server to the requested doc “first. html”.. the words separated by slash are the directory names - following unix rules - the internet originally comprised computers running the unix operating system…

Story Short: the URL says it would like to use the HTTP protocol to connect to a web server on the internet called www.example.com, and request the doc first.html

Question 23

What happens when a server receives a request for a directory name rather than a specific file

Answer 23

it looks for a default document, typically named index.html
note: make sure you check with your hosting service to make sure you give you default file the appropriate name i.e. index.html, index.php, etc.

Question 24

Name one purpose of the index file…

Answer 24

Useful for security - Some (depending on their configuration) display contents of the directory if the default is not found - One way to prevent people from snooping around in your files is to be sure there is an index file in every directory

Question 25

Describe html structure…

Answer 25

….

Question 26

How does the browser display web pages?

Answer 26

1. Type a URL in your browser (client agent)
2. The browser sends an HTTP request to the Server
3. The server looks for the file and responds w/ an http response (default file, if no specific doc was requested)
4. Browser parses the document. If it has images, style sheets, and scripts, the browser contacts the server again for each resource
5. Page is assembled in the browser window (client agent)