Home / IB DP Computer Science Option C: Web science -: C.4 –The evolving web SL Paper 2

IB DP Computer Science Option C: Web science -: C.4 –The evolving web SL Paper 2

Question

The World Wide Web can be divided into three categories: the surface web, the dark web and the deep web.
The dark web is only accessible by using specialist software, such as TOR and I2P. Many users of the dark web use it to protect their anonymity.
Many users of the dark web use peer-2-peer (P2P) networks for activities like torrent streaming. This opens up ports on the computer to upload and download data.
a. Distinguish between the surface web and the deep web.[2]
b. Explain how a user’s anonymity can be maintained while accessing the dark web.$[3]$
c. Explain why users have concerns about opening up ports to upload and download data.$[3]$
d. The founders of the World Wide Web intended it to be a decentralized and democratic environment.[6]
To what extent have the aspirations of the founders of the World Wide Web been met?

▶️Answer/Explanation

Ans:

a. )
The surface web is the part of the web that can be reached by a search engine whereas the deep web cannot;
The deep web may consist of dynamic content such as the result of database queries or may be protected proprietary content;

b. )
The dark web uses a layered encryption system;
Data is routed through a large number of intermediate servers;
Which means it is almost impossible to decrypt the information layer by layer;
With the result that the user’s details are practically untraceable, and their anonymity can be maintained;

c. )
A port is used to facilitate the communication between a computer and an application;
Certain ports such as Port 21 (FTP), 23 (Telnet) and 80 (HTTP) are reserved;
Every time a port is opened on a computer it provides access to that computer;
This means that the security of that computer may be potentially compromised every time a new port is opened;
Or port conflicts may occur when more than one application tries to use a specified port;

d. )
World Wide Web has enabled citizens to communicate easily and for ‘ordinary’ citizens to express their opinions;
Therefore, the ability to publish is not confined to certain ‘privileged’ groups such as broadcasters and journalists;
The World Wide Web has to a large degree given access to common resources to all citizens globally who have access to the Internet;
However, it can be argued that the evolution of the World Wide Web has led to a greater centralization of power, for example the digital oligarchs
(Microsoft, Google, Amazon, Apple, Facebook);

This centralization has led to a reduction in democracy as the digital oligarchs have an increasing stranglehold over the lives of their ‘digital subjects’ through the aggregation, analysis and monetarization of their data;
There are still issues with a lack of digital democracy, for example, many citizens may not have access to the World Wide Web, either through income, geography or necessary skills;

Question

Pugh University has a website that allows computer science students to enter their name and customize the web pages.
Consider the section of HTML and CSS code shown below.
File name: index.html

<!DOCTYPE html>
<html>
<body>
<script>
                                         function setVar(){
                                                var subject=document.getElementById(“kippers”).value;
                                                document.getElementById(“subj”).innerHTML = subject;
                                                 }
</script>
<h2>My First Page</h2>
<p>Welcome to the <span id=”subj”></span> Faculty</p>

 <input type=”text” id=”kippers”/>
<button onclick=”setVar();”/>clickme</button>
</body>
</html>

When a student enrolls, they must enter their name on a web page. Before being added to the database, the system should check that the name typed is not blank and that it has not already been added to the database.

Consider the following URL:
https://www.follettibstore.com
The common gateway interface (CGI) offers a standard protocol for web servers.
a.i. State the output of the index.html file in the web browser.[2]
a.ii.Describe the processing that takes place when the user inputs “Pugh” into the text box and then uses the clickme button.[3]
b. Explain why these two validation checks occur on different computer systems.
c. Explain how website certificates are used to authenticate a user’s browser through secure protocol communications like HTTPS.[3]
d. Describe the working of the common gateway interface (CGI).[4]
e. Pugh University uses cloud computing services, such as Google Docs or Office 365.$[4]$
Describe how cloud computing is different to a client-server architecture.

▶️Answer/Explanation

Ans:

a.i. )
Award [1] for the text within the $\langle p\rangle$ tags (My First Page large font/Welcome to the Faculty in a smaller font;
Award [1] for the text box and correctly labelled button;
My First Page
Welcome to the Faculty
clickme

OR
Initially it displays:
My First Page – in large font;
Welcome to the Faculty – in normal font;
A text box + a button labelled “clickme”;
A Then if you type in the text box and then press the button, it displays what is typed between “Welcome to the” and “Faculty” – e.g. type “Science” and it will display; “Welcome to the Science Faculty”;
Note: Students either show the output on the web-browser or describe what would be displayed on the web-browser.

a.ii)
The button’s onclick method is called, i.e. setVar();
This first sets the variable subject to the value of the HTML element with id kippers, i.e. the text box;
and then sets the inner text of the element with id subj, i.e. the span, to “Pugh”, so that the display is “Welcome to the Pugh Faculty”;

b. )
Award [1] for identifying correct validation check.
Award [1] for describing the validation check.
Presence check:
It happens in JavaScript in the web page on the client; because this will save the server handling many transactions/to avoid sending a null value that will need to be handled by the server;
Lookup check
It happens on the server; because the database is stored on the server rather than on the client’s computer;

c. )
The website certificate is used to initiate sessions between the user’s browser and the server;
The web server sends the browser a copy of its SSL certificate;
If the browser trusts the certificate, it sends a message to the web server;
The web server sends back a digitally signed acknowledgement to start an SSL encrypted session;

d. )
The Common Gateway Interface (CGI) is used to provide interactivity to web applications/enable forms to be submitted;
It uses a standard protocol that acts as an intermediary between the CGI program and the web server;
The CGI allows the web server to pass a user’s request to an application program;
And then the forwarded data is received to the user’s browser;

e.)
Cloud computing is based on sharing computing resources over the internet;
Cloud computing can be offered as a service to individuals and companies (SaaS) which means they do not have to maintain the infrastructure;
Cloud computing and applications are more scalable than client-server architectures;
Client-server architecture does not need to be operating over the internet, but instead can be limited to a local network;
Client-server architectures may require more maintenance of the infrastructure by the organization who are using it;
cloud computing is typically more resilient than client server, because the services offered are more widely distributed, rather than being concentrated on one server or on a small number of alternative servers;

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