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Computer Science CIE > Theory 9 The Internet and its uses > Flashcards

Theory 9 The Internet and its uses Flashcards

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1
Q

What is the Internet and what is a protocol?

A

A global network of computers which includes smartphones, laptops, games consoles, IoT devices etc.

Standardised using TCP/IP: a protocol which allows networks to talk to each other.

Protocol: a specific set of rules used communication

All transmissions, worldwide, must follow the rules in order for the transmission to be successful.

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2
Q

What is the World Wide Web?

A

A set of interconnected web pages which a web page can contain text, images, video, animation and sound.

You access a web page by typing its URL (Uniform Resource Locator), e.g. https://www.st-albans.herts.sch.uk/

Hyperlinks allow web pages to link to each other.

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3
Q

What is a URL?

A

Uniform Resource Locators
A website address
You can also access a webpage by a hyperlink and from a result in a search

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4
Q

Identify each part of this URL: https://www.st-albans.herts.sch.uk/webpages/about.html

A
  • Https : protocol
    • St-albans.herts.sch.uk : domain
    • Webpages : folder / location
    • About.html : web page
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5
Q

Advantages of URLs

A

Easy to remember
Easy to type
The name usually means something
The geographic location is usually indicated

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6
Q

Disadvantages of URLs

A

Not the actual physical address of anything
The domain name server needs to be kept updated.

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7
Q

What is the HTTP Protocol?

A

The http protocol manages the transmission via the internet. It works as a request-response protocol and stateless protocol. Sessions are maintained using cookies.

https is secure and uses public-private key encryption

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8
Q

What is a Browser?

A

A browser is a program that allows you to visit a website, retrieve and display the information on a remote webpage

It:
* Displays (render) remote webpages
* Interprets HTML documents
* Translates embedded scripting, e.g. JavaScript
* Provides functions such as bookmarks and history
* Stores and retrieves cookies
* Makes use of plugins to play video, for example
* Uses a variety of protocols such as HTTPS as well as HTTP
* Provides navigation tools and an address bar

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9
Q

What are cookies?

A

Cookies are small text files stored on your computer by a website that you have visited. They are used for:
* Login information
* Information suitable for advertisers to use
* Customised webpage details
* Shopping basket contents and one-click purchasing
* Distinguishing between new and repeat visits

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10
Q

State and explain the two types of cookies

A

Session cookies
* A session is a single interaction with a website
* Session cookies are only stored for a single session
* Then they are replaced the next time you visit the website

Persistent cookies
* These are created the first time you visit a website
* They are kept until they expire

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11
Q

Advantages of cookies

A

Remembers data between visits

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12
Q

Disadvantages of cookies

A
  • Privacy issues - you are being tracked and may be targeted by adverts based on your history
    • Other users of your computer may be able to work out your interests
      Not inherently secure but data can be encrypted
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13
Q

What do you need to connect to the internet?

A
  • A web browser
    • Computer
    • Internet connection
    • Modem and router (often incorporated into one unit)
      An internet service provider (ISP) e.g. Virgin Media, BT
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14
Q

What is a modem?

A

A modem receives signals from your Internet Service Provider ( ISP ) through phone lines, optical fibre or coaxial cable and converts them to a digital signal.

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15
Q

What is a router?

A

A router creates a network between the computers in your home and forwards traffic between the internet and your computers. The network might be wired (ethernet cables) or wireless.

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16
Q

What is an ISP?

A

An ISP allows your devices to connect to the internet. They:
* Provide a router / modem
* Monitor your usage
* Give you an IP address
* Determine allowed bandwidth
* Provides security services e.g. some blocking of malware
Help you find web pages on the internet using DNS (domain name servers)

17
Q

What are web pages?

A

Websites are hosted on webservers. These are:
* A computer with special server technology
* Connected to the internet

They process requests from clients which are usually made up of browsers requesting webpages.

18
Q

What are IP addresses?

A

Every computer on the internet has a unique public IP (IPv4) address. Your home IP address is likely to be dynamic, meaning that it changes frequently. You can pay for static IP addresses but this only really done by large companies.

Within your home you have private IP addresses which are unique within your home, e.g. 192.168.0.1

There are two formats: IPv4 and IPv6

IPv4 is the older format and is made up of 4 bytes per IP address. They are written using decimal with dots in between the different parts, e.g. 172.16.254.1

IPv6 is the newer format and are written as hexadecimal separated by colons, e.g. 2001:db8::8a2e:370:7334. IPv6 was created to replace IPv4 as it provides many more IP addresses.

19
Q

Advantages of IP addresses

A
  • It is a location-based address
    It can be split using bit masks to extract particular elements
20
Q

Disadvantages of IP addresses

A
  • Hard to remember
    • Doesn’t mean anything to you
    • Not tied to specific geographic locations
      It can change
21
Q

What are MAC addresses?

A

Permanent physical identifier of an electronic device connected to a network
Not the location of a device, the identification of a device
It is unique, worldwide across all networks and cannot be changed.

22
Q

Advantages of MAC addresses

A
  • Unique
    • Can be used to block/allow devices (black list / white list)
23
Q

Disadvantages of MAC addresses

A
  • Hard to remember
    • Doesn’t identify the network, user or location
    • If the device is changed, the MAC address changes
    • No way of associating with a domain (www.bbbc.co.uk) or an IP address. Domain name servers do this for IP addresses.
24
Q

What is DNS?

A

The Domain Name System (DNS) is a protocol which translates user-friendly domain names (e.g. abc.co.uk) to IP addresses (e.g. 212.58.244.23)

This allows you to access a web page using a familiar URL and not worry about the actual IP address of the webserver.

25
Q

How Web Pages are located

A
  1. The client requests a URL via a web browser
    1. The browser sends the domain name to a domain name server (DNS)
    2. The DNS finds the IP address mapped to the domain name and returns it to the browser
    3. The browser sends a GET request to the IP address for the page required
      The requested page is returned to the client’s IP address and the HTML is rendered by the browser
26
Q

What is data interception?

A

With these attacks, someone monitors data transmissions looking for unencrypted passwords etc. This is called network sniffing

Remember that any unencrypted network traffic can be understood by anyone

These are sometimes called man-in-the-middle attacks

27
Q

What are DDoS attacks?

A

This is when you send so much traffic to a website that you overwhelm it and it cannot respond to genuine traffic. The distributed part is using many devices to carry out the attack. Using multiple computers with different IP addresses makes it easy to block the attack by simply blocking a single IP address.
Malware can be used to create botnets.

28
Q

Define Hacking

A

Hacking is exploiting weaknesses in websites or system security to access private or corporate information.

29
Q

Define Malware

A

Malware is software designed to disrupt, damage or gain unauthorised access to computer systems

30
Q

How does malware get onto your computer?

A

Malware gets on your computer or phone by:
* Taking advantage of weaknesses in the programs running on your computer
* Tricking you into downloading it
* Hiding inside something else

31
Q

Define virus

A

A program that embeds its code inside other programs running on your computer

32
Q

Define worms

A

Makes copies of itself and spreads to other devices. One common way is by sending itself by email to all your contacts. A worm doesn’t hide in other programs, unlike a virus.

Computer Science CIE (2 decks)

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