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Q&A-KCSE Computer Studies Paper 1

Mention at least two trends in the technological revolution of computers.

  • Continual decrease in computer size
  • Improved speed and power of processing
  • Decrease in computer physical size and its related facilities cost
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Social engineering is where someone is tricked or manipulated into providing secure information or access to a secure system. Describe each of the following social engineering techniques.

Blagging

  • This is where a victim is tricked/persuaded by a fraudster to give their details or payment information for a false reason/purpose;

Phishing

  • This is where the victim receives and responds to communication that appears to be from a valid or known source but is in fact fraudulent. (It allows the fraudster to capture private information before the victim realises);

Shouldering

  • This is where someone watches and records\remembers a victim entering their pin or security information such as passwords. (They can then use this information to gain access to a system)
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Differentiate between a compiled and an interpreted program

  • A compiled program will only execute on a processor of specific type/family/with same instruction set
  • A program run using an interpreter can execute on a computer with any type of processor
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Differentiate between uploading and downloading a file

Uploading a file  refers to the process of transferring a file from a local computer to a remote webserver while downloading a file refers to the process of transferring or copying a file from a remote webserver to a local machine

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List any two components of an expert system                                (2marks)

  • Knowledge base – is the systems’ database of knowledge about a particular subject. It contains relevant facts, beliefs, assumptions and procedures for solving a particular problem
  • Inference engine – this is the software that controls the search for knowledge in the knowledge base and produces conclusions. It takes the problem posed by the user and seeks to analyze it in order to arrive at a conclusion.
  • User interface- this is the display screen that enables the user interact with the system.
Give two uses of spreadsheets in a government office concerned with carrying out national census
Tallying population size Establishing demographic trends Drawing pie charts to show population share by gender Doing census budgets

Name three of the stages in the system life cycle

fact finding
feasibility study
analysis
design
testing
documentation
implementation/changeover/installation
evaluation
maintenance

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Describe the difference between distributed and sequential processing on how they process instructions

  • Sequential processing occurs in the order that the tasks are received while distributed processing where more than one computer or CPU is used to run specific programs.
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1 (a) Computer networks are valuable to many businesses and individuals.
(i) State the purpose of network protocols

Any one of:
To allow connected machines to communicate
To provide the rules of communication between two networked devices

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Explain, with examples where appropriate, the following five computer terms.

(a) Buffer

(b)batch processing

(c) e-commerce

(d) simulation

(a) Buffer

  • temporary storage or memory which compensates for the difference speed of peripherals and the CPU

(b)batch processing

  • processing doesn’t start until all data is collected
  • JCL (any reference to Job Control Language)
  • no need for user interaction
  • processed all in one go
  • done at “quiet” times
  • e.g. billing, payroll, cheque processing

(c) e-commerce

  • electronic commerce
  • buying and selling products/services using the internet/computer networks

(d) simulation

  • studying the behaviour of a system by using a model/mathematical representation
  • results can be predicted
  • e.g. flight (or other) simulator, modelling hazardous chemical process

(e) Email

  • sending messages from one device to another using computer networks/Internet
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Explain the functions of the following parts of the CPU

Control Unit; Decodes instruction; Controls the fetching and writing of data;

Arithmetic Logic Unit/ ALU; Executes mathematical instructions;  Executes logical instructions; Compares values held in registers;

 Clock; Controls the number of instructions carried out each second;   allows the CPU to synchronize operations;

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State the functions of the following protocols

POP -Stands for post office protocol

  • used to download emails from email servers

SMTP- Simple Mail Transfer Protocol

  • used to send emails to email servers and transfer emails between servers

FTP - Stands for the file transfer protocol

  • handles file uploads and downloads
  • transfers data and programs and not viewable content

 

State the functions of the following protocols

POP -Stands for post office protocol

  • used to download emails from email servers

SMTP- Simple Mail Transfer Protocol

  • used to send emails to email servers and transfer emails between servers

FTP - Stands for the file transfer protoc

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What is a referential integrity constraint?

  • It requires that a foreign key must have a matching primary key or it must be null
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Distinguish between a PAN and a LAN

A PAN exist around a single person whereas a LAN covers a larger area

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Ahmed sees the message “Set your browser to accept cookies”.
Explain why some websites make this request.

  • to enable logon information to be kept on his computer
  • to provide pages customised for Ahmed the next time he logs on
  • to implement shopping carts and one-click purchasing
  • to be able to distinguish between new and repeat visitors to the website
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Give one benefit and one disadvantage of the use of wireless technology.

Advantages

  • no wires
  • fast/high-speed wireless Internet access
  • WLAN is faster than a modem or mobile
  • WLAN for working at home one day a week/teleworkers
  • see internet content away on the move
  • create and send multimedia messages to mobiles or e-mail
  • picture messaging - send photos/pictures text/sound/recorded
  • greetings from mobiles to mobiles/PCs
  • instant transmission - no busy signals/no searching for phone jacks
  • download e-mail and file attachments on mobile
  • watch live webcast on mobile/hotspot
  • listen to streaming video on mobile/hotspot
  • news/weather/sport/games while on the move
  • access information from mobile anytime
  • send/receive/delete e-mail while on the move
  • wireless Inbox on mobile - to contacts and calendar
  • view business appointments while out of the office on mobile
  • send corporate e-mail while out of the office - even behind a firewall on mobile
  • wireless internet connection from chat rooms for discussions with colleagues while on the move
  • give visual demonstrations from mobile and colleagues watch back at the office

 disadvantages e.g.

  • WLAN speeds are slower than Net access at work/narrow band width
  • any one within the WLAN nodes range with an appropriate device can use your WLAN and broad band link
  • any one who walks past your house or WLAN linked into a corporate system can access sensitive information or credit card details
  • 3G phones not compatible with 2G phones
  • Blue tooth - has limited range
  • blocked signal/distorted signal/weak signal/lag
  • health problems from microwaves
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A computer is upgraded to a dual-core CPU.
Explain how the upgrade can affect the performance of the computer.

  • It can now process two instructions simultaneously (where suitable) increasing the performance.

 

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Ochieng manages a network for an organisation.
(a) Two computers are assigned the same IP address.
Explain why Ochieng must change the IP address of one of the computers.

  • Devices must have a unique IP address because otherwise, a switch would not know which of the two was the correct device to send packets to

(b) Identify the network topology that requires a server.

  • Star topology

Ochieng manages a network for an organisation.
(a) Two computers are assigned the same IP address.
Explain why Ochieng must change the IP address of one of the computers.

  • Devices must have a unique IP address because otherwise, a switch would not know which of the two was the correct device to send packets to

(b) Identify the network topology that requires a server.

  • Star topology
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(ii) State what ROM and RAM store.

 

ROM stores BIOS / bootstrap / start-up 

RAM stores currently executing programs and data

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Give three characteristics of an IP address.

  • consists of values between 0–255 / 0–FFF
  • values are separated by full stops/colons
  • it is a unique address
  • can be static or dynamic
  • can be public or private
  • can be IPv4 / have four groups of digits
  • can be IPv6 / have eight groups of digits
  • in IPv6: can replace groups of zeros.
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