1.2.3 Internet principles of operation WAN, LAN AND MAN ISP (DATA, Terms of service) Internet Browser (plugins .flv) URL Hyperlinks Bandwidth Packet transmission DDOS – Distributed Denial of Service Attack (lots of requests)
Internet Protocols HTTP governs the transmission of data via the internet works on the idea of request response client makes a request and the server responds to this. The actual transfer of data is done by TCP this handles the transfer of data as well as ensuring error free transmission. HTTPS – secure - encryption
HTML Have a go!
Distinguish between HTML structure and presentation Structure consists of the mandatory parts of an HTML document plus the semantic and structured markup of its contents. Presentation is the style you give the content. In most cases presentation is about the way a document looks, but it can also affect how a document sounds – not everybody uses a graphical web browser.
What is HTML HTML HTML (Hypertext Markup Language) is the recognized markup language utilised in forming web pages. It defines the composition of web pages using markup. HTML elements are the primary units of HTML pages. HTML elements are denoted by tags. HTML tags label parts of content like heading, paragraph, and table. Browsers do not show the HTML tags but they are used to deliver the content of the page. HTML Tags HTML tags are element names enclosed by angle brackets. HTML tags usually come in pair. The first tag in a pair is the start tag and the second tag is the end tag. The end tag is written like the start tag, but with forward slash inserted before the tag name. The start tag is also called the opening tag and the end tag the closing tag. All HTML documents must start with a document type declaration: <!DOCTYPE html>. The HTML document itself begins with <html> and ends with </html>. The visible part of the HTML document is between <body> and </body>. HTML tags are not case sensitive. HTML Attributes All HTML elements can have attributes. They provide additional information about the element. They are always specified in the start tag. They usually come in name/value pairs.
Structure vs. Presentation The composition of a webpage could be regarded as a mixture of the following four elements: Content is the general term used for all the browser-displayed information elements like text, audio, still images, animation, video, multimedia and files of web pages. It does not require any additional presentational markups or styles in order to fully relay its message. Structure is the custom of using HTML on content to transmit substance and to define how blocks of information are structured to one another. Examples: “this is a list” (i, d, k), “this is heading and subheading” (<h1>, <h2>, …, <h6>), “this section is related to” (<a>), etc. Presentation of Style is anything related to how the content and structure is presented. Examples: size, colour, margins, borders, layout, location, etc. Behaviour or Interactivity is the implementation of a client-side script to generate two-way flow of information between the webpage and its users. Example: JavaScript Most of the time it is difficult to clearly distinguish content from structure. For example, the <img> tag, as a structural element, is used to produce graphical content. In practice, the composition of a webpage can simply be viewed as a mixture of three elements: Structure, Presentation, and Behaviour. The following terms: separation of content and presentation, separation of meaning and presentation and separation of structure and presentation are being used correspondingly. Nonetheless, all of these terms basically refer to the separation of the content made meaningful by structure and presentation or simply the separation of the structure (HTML) and presentation (CSS).
Show understanding of the concepts of MAC address, Internet Protocol (IP) address, Uniform Resource Locator (URL) and cookies MAC address A MAC address is given to a network adapter when it is manufactured. It is hardwired or hard-coded onto your computer's network interface card (NIC) and is unique to it. Something called the ARP (Address Resolution Protocol) translates an IP address into a MAC address. The ARP is like a passport that takes data from an IP address through an actual piece of computer hardware. All devices on the same network subnet have different MAC addresses. MAC addresses are very useful in diagnosing network issues, such as problems with IP addresses. MAC addresses are useful for network diagnosis because they never change, as opposed to a dynamic IP address, which can change from time to time. For a network administrator, that makes a MAC address a more reliable way to identify senders and receivers of data on the network.
URL A uniform resource locator (URL) is the address of a resource on the Internet. A URL indicates the location of a resource as well as the protocol used to access it. A URL contains the following information: The protocol used to a access the resource The the location of the server (whether by IP address or domain name) The port number on the server (optional) The location of the resource in the directory structure of the server A fragment identifier (optional) Also known as a Universal Resource Locator (URL) or Web address. A URL is a type of uniform resource identifier (URI). In common practice, the term URI isn't used, or is used synonymously with URL, even though this is technically incorrect.
cookies Cookies are NOT programs. They don’t do anything at all. They are simple ’text files’ which you can read using the Notebook program on your own PC. Typically, they contain two pieces of information: a site name and unique user ID When you visit a site that uses cookies for the first time, a cookie is downloaded onto your PC. The next time you visit that site, your PC checks to see if it has a cookie that is relevant (that is, one containing the site name) and sends the information contained in that cookie back to the site. The site then ’knows’ that you have been there before, and in some cases, tailors what pops up on screen to take account of that fact. For instance, it can be helpful to vary content according to whether this is your first ever visit to a site – or your 71st.
Question RockICT is a music business that has a website to allow customers to view and buy the products it sells. The website consists of web pages. (a) Describe what is meant by HTML structure and presentation for a web page.
Answer Any four from: − Structure and presentation are defined using (mark-up) tags − Structure and presentation dictate the appearance of the website − Structure is used for layout − Example of structure − Presentation is used for formatting / style − Example of formatting − Separate file / CSS can be used for presentation content
Question https://www.rockict.net/index.htm The URL for the music company’s website is: https://www.rockict.net/index.htm Part 1 Part 2 (i) Identify what Part 1 and Part 2 represent in this URL. Part 1 ................................................................................................................................ Part 2 ................................................................................................................................ [2] (ii) Describe what is meant by https. ...............................................................................................................................
Answer domain (name) file name/webpage name Any two from: Hypertext Transfer Protocol Secure // it is the access protocol // It is a protocol It means the website uses SSL/TLS It means data sent (to and from the webserver) is encrypted
Question When a customer enters the website, a message is displayed: “RockICT makes use of cookies. By continuing to browse you are agreeing to our use of cookies.” Explain why the music company uses cookies. ................................................................................................................................................... [2]
Answer 10(c) Any two from e.g. : To store items that a customer has added to an online shopping basket To store a customer’s credit card details To store log-in details To track what product a customer browses // Track music preferences Targeted advertising // making recommendations Personalises/customises the experience Shows who are new and returning customers To speed up log-in times To speed up/allow single click purchases Improves the experience
Question (d) The music company is concerned about the security of its website. The company uses a proxy server as part of its security system. Describe the role of a proxy server in the security system.
Answer Any four from: Prevents direct access to the webserver // Sits between user and webserver If an attack is launched it hits the proxy server instead // can be used to help prevent DDOS // help prevent hacking of webserver Used to direct invalid traffic away from the webserver Traffic is examined by the proxy server // Filters traffic If traffic is valid the data from the webserver will be obtained by the user If traffic is invalid the request to obtain data is declined Can block requests from certain IP addresses
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Answer – Part 1 (access) protocol – Part 2 domain (name) – Part 3 filename Four from: IP address is used to identify a device (on the Internet / network) IP address is allocated by the network/ ISP Can be used in place of URL IP addresses can be IPv4 or IPv6 IP address can be static... meaning it doesn’t change each time it is connected to the Internet IP address can be dynamic. meaning that it can change each time a device is connected to the Internet Any valid example (e.g. xxx.xxx.xxx.xxx orb xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx)
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Question Give the meaning of the following terms. HTML .................................................................................................................. http ............................................................................................................... https ..............................................................................................................
Answer HTML – HyperText Markup Language / language used to create web pages http – hypertext transfer protocol / protocol used by web browsers https – hypertext transfer protocol secure / secure protocol used by web browsers