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Q&A-KCSE Computer Studies Paper 1

Sarah uses a range of computing devices to complete her studies, including a desktop computer at home, a laptop at school and her mobile phone. Outline two advantages of cloud computing for Sarah.

Cloud computing refers to the delivery of on-demand computing resources over the internet. Instead of relying on a local server or personal computer, cloud computing allows users to access and utilize a wide range of computing services and resources hosted on remote servers.

  • Sarah could keep all of her files in the cloud and easily access these with her devices. This way she does not have to keep different version on her desktop and laptop.
  • Flexibility she could access the files from other devices such as the library etc.
  • Disaster recovery if she accidently dropped or damaged a device – all files would be easy to access.
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Define Domain integrity

Domain integrity - ensures that all data in  a field contain valid values

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Identify the protocol used to transfer data in networks.

  • TCP/IP
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State the primary function of the Dynamic Host Configuration Protocol (DHCP) protocol.

  • it generates and/or allocates an IP address
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A company has a website that is stored on a web server.
(a) The website data is broken down into packets to be transmitted to a user.
Describe the structure of a data packet.

  • it has a header that contains the destination address, the packet number, and the originator’s address
  • it has a payload
  • it has a trailer.

 

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Describe the input, processing and output from a computerised traffic-control system.

input

  • from sensors
  • from camera images [Max 2]

processing

  • analyse data from sensors
  • calculate average traffic flow/speed
  • send signals to adjust change lights/timing

output

  • change lights at the junction
  • change timing plan
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Peter has installed internet on his home computer in order to use it for browsing. State three ways in which he would prevent viruses from infecting his computer.                                                        (3 marks)

  • Installing the latest versions of antivirus software
  • Avoiding downloads from untrusted sites
  • Scanning removable storage media for viruses before use
  • Scanning attachments for viruses before opening or downloading
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State a circumstance under which dry-run testing is performed when developing a program (2mks)

  • To detect and remove errors
  • To confirm if the program produces the expected output
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Describe the role of a repeater when used in a network.

a repeater will amplify a signal and resend it to overcome reduction in signal strength (attenuation) because over a distance network signals diminish in size/amplitude (are attenuated) due to characteristics of the media.

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Describe the role of the one-dimensional array in programming

  • holds an indexed sequence of variables of the same data type
  • Arrays can be used to store values of the same data type and the array is then used as a singular variable to increase efficiency
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Students are using their wireless notebooks to complete their work in a classroom. They will need to connect wirelessly to a printer to print their answers at the end of the lesson.
Describe how CSMA/CA (Carrier-sense multiple access with collision avoidance) operates in the above scenario.

  • All nodes ‘listen’ for traffic to sense when the network is idle.
  • When a node wishes to transmit, it transmits a ‘request to send’ frame’ (RTS)
  • The intended receiving device will transmit a ‘clear to send’ (CTS) frame if it is available.
  • All other nodes ‘sense’ the network is busy and wait a random amount of time before trying to transmit
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(a)State what is meant by the terms:

Parallel data transmission...................................................

Serial data transmission......................................................

(a)State what is meant by the terms:

Parallel data transmission

  • 8 bits/1 byte/multiple bits sent at a time  
  • using many/multiple/8 wires/lines

Serial data transmission

  • one bit sent at a time over a single wire
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Clearly define a computer

  • A computer is an electronic device that operates (works) under the control of programs stored in its own memory unit
  • An electronic device that accepts data, as input and transforms it under the influence of a set of special instructions called programs, to produce the desired output (referred to as information)
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 Complete the data dictionary below for the Student entity.

  • StudentID: String
  • FirstName: Required 1
  • Year: 2 1
  • Email: Email address containing @ sign 1
  • AccountBalance: Real
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What is a primary key?

  • an attribute/combination of attributes chosen to ensure that the records in a table are unique
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List three types of errors that are likely to exist in a program                             (3 marks)

Syntax errors-Incorrect use of programming language

Logical errors- The program do not give the expected output

Runtime errors- Premature end of a program

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Give one advantage using a star network rather than a ring network.

  • star - if one computer goes down the others can still be used
  • ring - if one computer goes down the others can not be used
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Describe the query criteria given below

 

(a) Like "*kenya*"

  • Returns the records of all countries that contain the string "kenya"

(b) Like "*ina"

  • Returns records for all countries/regions whose names end in "ina", such as China and Argentina.

(c) Like U*

  • Returns records for all countries/regions whose names start with "U", such as UK, USA, and so on.

(d) Not Like U*

  • Returns records for all countries/regions whose names start with a character other than "U".

(e) >= "Mexico"

  • Returns records of all countries/regions, beginning with Mexico and continuing through the end of the alphabet.

(f) Like "[A-D]*"

  • Returns records for countries/regions whose names start with the letters "A" through "D".

(g) "USA" Or "UK"

  • Returns records for USA and UK.

https://support.microsoft.com/en-us/office/examples-of-query-criteria-3197228c-8684-4552-ac03-aba746fb29d8

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Explain one drawback to a user if the program is distributed as freeware

The user is not allowed to access the source code so, they cannot tailor the software to their needs and  they cannot fix any bugs in it

The software is still covered by copyright

The user must get the owner’s permission to do anything beyond using it

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Give one reason why a phased implementation would be the best approach to follow in this case.

  • This approach causes minimum disruption
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