IBDP Computer Science A2.3 Data transmissions HL Paper 2 - New Syllabus

IBDP Computer Science HL Paper 2 - All Chapters

Question 

Alexia and Jay are discussing their use of online resources to prepare for their IB examinations. They often visit websites such as BBC Bitesize.

Alexia refers to accessing the websites as “surfing the internet” and Jay refers to the resources as being “on the web”.

(a) Distinguish between the internet and the World Wide Web. [2]

The uniform resource locator (URL) for the BBC Bitesize website is as follows:

https://www.bbc.co.uk/bitesize/index.htm

(b) Identify two characteristics of a URL. [2]

Jay wants to transfer a file to Alexia and suggests they use file transfer protocol (FTP).

(c) Identify two characteristics of file transfer protocol. [2]
(d) Explain how a web browser functions. [3]

Most-appropriate topic code

• A2.1: Network fundamentals — parts (a) and (b)
• A2.3: Data transmissions — part (c)
• A2.1: Network fundamentals — part (d)
▶️ Answer/Explanation

(a)
For the correct answer:

  • The internet is a global network of interconnected computer networks that communicate using internet protocols and IP addresses.
  • The World Wide Web is a service that operates on the internet. It is a collection of information and resources accessed through web browsers using protocols such as HTTP or HTTPS.

Explanation: The internet is the underlying network infrastructure, whereas the World Wide Web is one of the services that uses this infrastructure.

(b)
For the correct answer, any two characteristics of the URL may be identified:

  • Protocol: https
  • Host: www.bbc.co.uk
  • Domain: bbc.co.uk
  • Path: /bitesize/index.htm
  • A URL uniquely identifies a resource on the web.

Explanation: A URL provides the information required to locate and access a particular resource. In this example, https specifies the protocol, while www.bbc.co.uk identifies the host.

(c)
For the correct answer:

  • FTP establishes two processes or connections: one for control and one for data transfer.
  • FTP commonly uses port 21 for the control connection and port 20 for data transfer.
  • FTP facilitates the efficient transfer of files between a client and a server.

Explanation: FTP is specifically designed for transferring files between systems. Its separate control and data connections allow commands and file-transfer data to be handled independently.

(d)
For the correct answer:

  1. The web browser uses an appropriate protocol such as HTTP or HTTPS to communicate with the web server.
  2. The browser uses the URL to request the required resource. The URL can be resolved through a DNS server to obtain the corresponding IP address, after which the browser sends the request to the web server and receives the response.
  3. The browser processes and renders the returned data, such as HTML, so that the web page can be displayed. It can also support multimedia features and security services such as authentication and encryption.

Typical request and response process:

Enter URL
   ↓
DNS lookup
   ↓
Obtain IP address
   ↓
HTTP/HTTPS request
   ↓
Web server
   ↓
HTTP/HTTPS response
   ↓
Browser renders the webpage

Explanation: A browser is more than a program that simply “shows information”. It communicates with web servers using network protocols, retrieves resources, processes the returned data, and renders the webpage according to relevant web standards.

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