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Joe plays online games using the world wide web - Edexcel - GCSE Computer Science - Question 6 - 2020 - Paper 1
Question 6
Joe plays online games using the world wide web. (a) A sequence of processes is required to open a web page. Describe this sequence of processes. (b) The web page ... show full transcript
Worked Solution & Example Answer:Joe plays online games using the world wide web - Edexcel - GCSE Computer Science - Question 6 - 2020 - Paper 1
Step 1
A sequence of processes is required to open a web page. Describe this sequence of processes.
Answer
To open a web page, several key steps occur in sequence:
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User Input: The process begins when the user types a URL into the browser's address bar or clicks on a link.
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DNS Resolution: The browser first sends a request to a Domain Name System (DNS) server to translate the domain name into an IP address, which is the location of the web server that hosts the desired webpage.
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Establishing Connection: Once the IP address is retrieved, the browser establishes a connection with the web server using the HTTP or HTTPS protocol. This involves a handshake process to ensure a secure connection, especially for HTTPS.
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Sending the HTTP Request: After establishing the connection, the browser sends an HTTP request to the server asking for the contents of the web page. This request may include additional headers with information about the browser, accepted formats, etc.
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Server Response: The web server processes the request, retrieves the requested page, and sends back an HTTP response. This response usually includes the status code, indicating whether the request was successful (e.g., 200 OK) or if there was an issue (e.g., 404 Not Found).
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Rendering the Page: Upon receiving the response, the browser renders the webpage by processing the HTML, CSS, and JavaScript files, displaying the content to the user. The browser may also make additional requests for elements such as images and scripts that are included in the webpage.
Step 2
Describe how a merge sort works.
Answer
A merge sort is a highly efficient sorting algorithm that uses the divide-and-conquer approach. It can be broken down into the following steps:
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Divide: The initial array is divided into two halves. This process continues recursively until each subarray contains a single element.
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Conquer: Once we have reached individual elements, we begin to merge these elements back together. During the merging process, we compare the elements of the two halves and arrange them in sorted order.
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Merge: The process of merging two sorted arrays continues recursively up the tree of subarrays. Each time two arrays are merged, we ensure that every element from both halves is sorted relative to one another.
The merging occurs through repeated comparisons; for example, if we have two subarrays:
- Subarray A: [2, 5, 8]
- Subarray B: [1, 3, 7]
We will compare the first elements (2 and 1), add the smaller (1) to the sorted result, and proceed to compare the next elements until all elements have been merged together in sorted order resulting in:
Sorted Array: [1, 2, 3, 5, 7, 8].
The overall time complexity of merge sort is O(n log n), making it an efficient sorting algorithm, especially for large datasets.