Write a JavaScript function calculateAverage(), that will: - read THREE numbers in from the HTML form as marks. - output the total mark. - output the average of the three marks. The average mark must be output as a real number. b) Why is JavaScript validation regarded as a potential security risk? c) What measures and technologies could be put in place to mitigate this potential security risk? A2 a) Describe how CSS allows separation of content and presentation for web pages? b) Describe a CSS rule, and what it consists of. Give an example to support your answer. c) What are modules in CSS3? d) Describe TWO disadvantages of using CSS, from a designer's perspective. e) What does the Cascading in CSS refer to? f) Where on an HTML page should a reference to an external CSS be placed? 

 

A3 a) What problem might be present with the DOM if jQuery is executed too early? b) How could this be avoided? Provide sample JavaScript code to support your answer. c) What is the difference between well-formed XML and valid XML? d) In relation to XML Data Modelling: - model a data source intended for a bank - model the account number, customer name, customer email address for each bank account that is to be held in the bank - provide XML mark-up for a bank account e) What does SOAP stand for and how is it used with XML?

 

 

 

B4 a) Expand each of the following acronyms: i) DNS. ii) UDP. iii) ARP. iv) IP. v) DHCP. vi) SMTP. b) Map the SIX protocols given in part a) above to the layers of the TCP/IP model. c) TCP is described as a connection-oriented protocol. i) Expand the acronym TCP. ii) What is meant by the term connection-oriented in reference to TCP? iii) Draw a diagram that illustrates how TCP establishes a connection between a client and server. You must demonstrate the threeway handshake in your answer. d) Briefly describe the role of DNS in the operation of the Internet. A diagram may be helpful.

 

 

B5 a) Expand the acronym HTTP. (1 mark) b) Briefly explain the difference between HTTP and HTTPS. (2 marks) c) HTTP is described as a stateless protocol. In this context: i) Define what stateless means. (1 mark) ii) Provide THREE examples of how a web application maintains state given that HTTP is stateless. (3 marks) d) Briefly describe what each of the following HTTP status codes represent, and why such a status code may be returned. i) 404 ii) 200 iii) 403 iv) 500 v) 401 e) Read the following simplified HTTP response header, then answer the following questions i) Briefly explain what the Content-Length field represents? ii) What is the protocol and status code of this HTTP response header? iii) The Content-Type field in this header is text/html. What would the header be if a portable network graphics image was the Content-Type? iv) A web browser made the request that generated this response. What would be displayed by the browser? (8 marks) HTTP/1.1 200 Date: Mon, 02 Apr 2018 13:23:19 GMT Server: Apache/1.3.29 Last-Modified: Sat, 31 Mar 2018 Content-Length: 38 Content-Type: text/html 

BCS

 

Welcome to the BCS

 

 

 

 

B6 a) Explain the difference between a packet switched and a circuit switched network. In your answer, state which type applies to the Internet. b) Internet Protocol (IP) is the main protocol that operates on the Network Layer. One of the fields within the IPv6 header is 'hop limit'. i) Describe the reasons for including the hop limit field in the IPv6 header. In your answer, include examples of where this field is put to effective use by network administrators for network diagnostics. ii) In the IPv4 header, the hop limit field is called TTL. Describe what TTL stands for, and why the designers of IPv6 renamed this field? c) Compare and contrast IPv4 and IPv6. d) Explain the importance of NAT, and the role it plays in the context of IPv4 addressing. e) Provide an example of a private IPv4 address.