2210_w16_qp_13
A paper of Computer Science, 2210
Questions:
11
Year:
2016
Paper:
1
Variant:
3
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2
Name each of the potential security issues described in the five statements below: Statement Security issue The act of gaining unauthorised access to a computer system Program code that can replicate itself with the intention of deleting or corrupting files stored in a computer A small file sent by a web server to a web browser; every time the user visits the website, data about user preferences is collected The act of illegally changing the source code of a program so that it can be exploited for another use Malicious code installed on a user’s hard drive or a web server which redirects the user to a fake website without their knowledge
5. The internet and its uses  →  5.3. Cyber security
5. The internet and its uses  →  5.1. The internet and the world wide web
Open
3
Five computer terms and seven descriptions are shown below. Draw a line to connect each computer term to its correct description. An error detection method that uses response and time out when transmitting data; if a response is not sent back to the sender in an agreed amount of time, then the data is re-sent Several bits of data sent down several wires, in both directions, but not at the same time Serial, simplex data transmission Description Computer term Several bits of data sent down several wires, in both directions, at the same time An even or odd number of bits set to 1 in a byte, used to check if the byte has been transmitted correctly One bit sent at a time, over a single wire in one direction only An additional digit placed at the end of a number to check if the number has been entered correctly A value transmitted at the end of a block of data; it is calculated using the other elements in the data stream and is used to check for transmission errors Parallel, half-duplex data transmission Parity check Automatic repeat request (ARQ) Checksum
2. Data transmission  →  2.2. Methods of error detection
Open
4
The Henslows Diner is a local restaurant. Staff currently use a keyboard to input a customer food order into a computer. The food order is then sent to the kitchen. State two disadvantages of using a keyboard to input a customer food order. A concept keyboard has a flat surface that is overlaid with images of food items available from the restaurant menu. Staff can click on an image to add the food item to a customer food order. The Henslows Diner wants to change to a concept keyboard to input customer food orders. Explain two benefits of making this change. The Henslows Diner stores personal data on a computer. This computer is connected to the Internet to allow the data to be backed up. There is currently one security method in place to protect the data on the computer from unauthorised access. This is a password. Give two other security methods that could be added to improve the security of the data. Describe how each method will keep the data safe. Security method 1 Description Security method 2 Description
5. The internet and its uses  →  5.3. Cyber security
2. Data transmission  →  2.1. Types and methods of data transmission
3. Hardware  →  3.3. Data storage
Open
5
Three switches, A, B and C, each send values of 0 or 1 to a logic circuit. Value X is output from the logic circuit. Switch A Switch B Output X Switch C Logic circuit Output X has a value of 1 depending on the following conditions: Switch A sends value 1 AND Switch B sends value 0 OR Switch B sends value 1 AND Switch C sends value 0 Draw a logic circuit to represent the conditions above. A B C X Complete the truth table for the conditions given at the start of question 5. A B C Working space X A microprocessor regularly samples the output, X. Each sample value is stored in an 8-bit register as shown below. One bit of this register is reserved as a parity bit. Five consecutive output values of 1 indicate a fault condition. Identify which of the following registers shows a fault condition. Parity bit Register Y Register Z Register When eight bytes of data have been collected, they are transmitted to a computer 100 km away. Parity checks are carried out to identify if the data has been transmitted correctly. The system uses even parity and column 1 is the parity bit. The eight bytes of data are sent together with a ninth parity byte: parity bit column column column column column column column byte 1 byte 2 byte 3 byte 4 byte 5 byte 6 byte 7 byte 8 parity byte Identify which of the eight bytes contains an error. byte Identify which column contains an error. column The incorrect bit is indicated where the byte number and column cross. Give the corrected byte. Calculate the denary value of the corrected byte. Considering the fault condition given in part , explain why it is very important that the incorrect bit is located and corrected.
2. Data transmission  →  2.2. Methods of error detection
1. Data representation  →  1.1. Number systems
Open
8
Four descriptions about compilers and interpreters are shown below. Draw lines to indicate which descriptions refer to a compiler and which descriptions refer to an interpreter. It is more difficult to debug the code since one error can produce many other associated errors. Compiler Description The speed of execution of program loops is slower. It produces fast, executable code that runs directly on the processor. It is easier to debug the code since an error is displayed as soon as it is found. Interpreter
4. Software  →  4.2. Types of programming language, translators and integrated development environments (IDEs)
Open
10
A manufacturer of aeroplane engines assigns a denary identification number (ID) to each engine. One engine has the ID: 0431 Convert this denary number to a 12-bit binary format. Show how this number would be represented in hexadecimal. The current status of the engine is sent to a computer in the aeroplane. Each piece of data collected is 8 bytes in size. Data collection occurs every 30 seconds. Calculate the number of kilobytes that would be needed to store the data collected during a 10-hour flight. Show your working. kilobytes At the end of the flight, all of the data are sent to the aeroplane engine manufacturer using the Internet. The computer in the aeroplane has a MAC address and an IP address. State what is meant by these two terms. MAC address IP address When sending this data, security is very important. Data are sent over the Internet using Transport Layer Security (TLS) protocol. Name the two layers that make up TLS.
2. Data transmission  →  2.1. Types and methods of data transmission
3. Hardware  →  3.4. Network hardware
Open