2023 specimen paper 1

Question 1

what is meant by a MAC address (4)

Answer 1

the address given to a device that uniquely identifies a device on a network. the MAC address is given by the manufacturer. it is made up of two parts in which the first part represents the ID number of the manufacturer, and the second part identifies the serial number of the device.

Question 2

give two uses of hexadecimal in computer science (2)

Answer 2

HTML color codes
IP (v6) address

Question 3

using left shift and move the binary number “01010010”

Answer 3

01001000

Question 4

what effect logical left shift does it have on the binary value? (2)

Answer 4

the left most bit is now lost following a left shift, hence changing the value of the binary value.

Question 5

describe the structure of a data packet

Answer 5

• the header - stores the IP address of the source device (sender) as well as the IP address of the destination device (receiver). it also contains the size of the packet (in bytes).
• the payload - the actual data in the packets.
  the trailer - contains the method of identifying the end of the packet. also includes some form of error checking to ensure packet arrives error-free.

Question 6

a company uses parallel half-duplex data transmission to transmit the data for the new videos to the web server. explain why parallel half-duplex transmission is the most appropriate method. (4)

Answer 6

parallel half-duplex data transmission is the most appropriate because it allows several bits of the video to be sent down several wires, increasing the speed of transmission of the larger data. since the bits are also transferred over a short distance, skewing can be avoided.

Question 7

describe what is meant by a DDoS attack (4)

Answer 7

multiple computers are used as bots and send numerous requests to a webserver in an attempt to flood the network with useless spam traffic. because the webserver becomes flooded with the spam traffic, it will not be able to service a user’s legitimate request. this leads to the website failing as a result.

Question 8

suggest one security device that can be used to help prevent a DDoS attack.

Answer 8

firewall
or proxy server

Question 9

give three characteristics of an IP address

Answer 9

• uniquely identifies a device connected to the internet.
• uses either 32 bits (IPv4_ or 128 bits (IPv6).
• can be static or dynamic.

Question 10

identify parts of a given URL below:
https://www.cambridgeaddessment.org.uk/index.html

https -
cambridgeaddessment.org.uk -
/index.html

Answer 10

• protocol
• domain name
• file name

Question 10

name three components that are part of the central processing unit (CPU) in a computer that has a Von Neumann architecture (3)

Answer 10

program counter
memory address register (MAR)
accumulator (ACC)

Question 11

describe the purpose of the control unit (CU) in a computer that has Von Neumann architecture (2)

Answer 11

the control unit sends control signals that manage the transfer of data and instructions within the CPU.

Question 12

state one purpose of a core in a CPU

Answer 12

to carry out instructions

Question 13

explain how dual core CPU help upgrade the performance of a computer (2)

Answer 13

the performance of the computer will be faster as now there are two core CPUs to carry out instructions simultaneously.

Question 14

identify two advantages of using high-level language over low-level language

Answer 14

easier to debug
easier to write/understand/code

Question 15

state one disadvantage to the programmer of using a high-level language instead of a low-level language.

Answer 15

may need to wait for the codes to be translated before running.

Question 16

state what is meant by an IDE

Answer 16

a suite of programs used to write and test a computer program written in a high-level language.

Question 17

state two characteristics of a robot

Answer 17

• it has electrical components.
• it is programmable.

Question 18

suggest two advantages of using robots, instead of humans, to build cars in the factory

Answer 18

• can work in places that are hazardous to humans
• can work 24 hours a day continuously

Question 19

describe what is meant by a character set (2)

Answer 19

• all the characters and symbols that can be represented by a computer system.
• each character and symbol is assigned a unique value.

Question 20

state one disadvantage of using unicode character set instead of the ascii character

Answer 20

the text stored takes up more storage space

Question 21

a student is using software to create 3D models. this process often requires the use of virtual memory. explain why virtual memory is needed for this process (3)

Answer 21

virtual memory is needed for this to extend the RAM capacity, stopping the 3D modelling software from freezing when the physical RAM is full. this also allows the computer to process the large amount of data required for 3D modelling.

Question 22

describe symmetric encryption (5)

Answer 22

• the data before encryption is known as plain text.
• to scramble the data, an encryption key, which is a type of algorithm, is used.
• the data after encryption is known as cipher text.
• encryption prevents the data from being understood by a hacker.

Question 23

an art gallery uses secure socket layer (SSL) to provide a secure connection when selling art on its website.
describe the process of SSL and explain how it provides a secure connection. (6)

Answer 23

• the user’s browser sends a message so that it can connect with the required website which is secured by SSL.
• the browser then requests that the web server identifies itself.
• the web server responds by sending a copy of its SSL certificate to the user’s browser.
• if the browser can authenticate this certificate, it sends a message back to the web server to allow communication to begin.
• once this message is received, the web server acknowledges the web browser, and the SSL encrypted two=way data transfer begins.

Question 24

give one reason why unicode takes up more storage space compared to ascii

Answer 24

it takes up more storage because ASCII uses more byte to represent a character, whereas unicode uses four bytes per character.