computer science 2020 paper 1

Unauthorised access ( brute force, hacking ) - firewall, password, security questions

Virus ( trojan, worm ) - firewall, anti-virus/malware

Phising - firewall, check sender

Data interception - encryptions

Spyware - anti-spyware

DDOS - firewall

LAN - Local Area Network

- small geographical area

- hardware owned / controlled by person 

Peer-to-Peer :   

-  all networks have equal status

- each computer stores its own files

- best suit smaller organisations with fewer computers

Client-Server :

- each computer ( client ) relies on another computer to provide / manage data

- clients do not usually store data and have no control over the network as a whole

- best suited to organisations with many computers

Benefits :

-  can access files from any device

-  can access files from anywhere

-  dont have to manually backup

-  may be free of cost

-  you do not need to buy more hardware

-  easy and quick to share files

-  more available storage on device

-  easier to increase storage capacity

Drawbacks :

-  cannot access files with no internet access

-  not in control of security

-  may cost monthly fee

-  may not be a backup ( if cloud fails data is lost )

-  data may be intercepted

-  if login details are forgotten / lost may not have access to files

-  connection may be slow

-  removal of people from workforce

-  change in demand for skills

-  need people to mange the hardware / software instead of medical expertise

-  skills may be lost

-  more secure than people seeing personal data

-  may be at risk of threats 

-  may be at risk if not backed up

-  more secure than people seeing personal data

-  replacing people with machines

-  loss of jobs

-  community will suffer

-  work will be completed faster

-  may find a cure faster

-  more reliable calculations

-  save more lives

When a file is stored on a hard disk it is stored as a series of segments. Over time, more files become fragmented. A fragmented disk takes longer to read, making the computer run slower.

Defragmentation software takes the fragmented files and rearranges the segments so that they run continuously. This decreases the time to take longer to read, speeding up the computer.

Each file will be stored consecutively.

-  Backup

-  Encryption

-  Compression

-  Firewall

-  Anti-virus

-  Anti-spyware

-  Anti-malware

ROM = Read Only Memory ( non-volatile )

-  store BIOS

-  store boot-up instructions

-  store data that should not be charged

-  store data that must be retained when the computer turns off

-  store firmware /OS fundamentals

Ali's tablet computer has 100 GB of secondary storage. There is currently 80 GB available.

Ali wants to transfer a series of clips onto his tablet. Each video is, on average, 200 000 KB.

Calculate an estimate of the number of video clips Ali can fit onto his tablet. 

Show your working.

80 GB = 80 000 MB = 80 000 000 KB       80 000 000 / 2 000 000 = 400

400 videos

Every website address has a URL with an equivalent IP address.

How URL is converted to IP address :

1.  URL sent to DNS

2.  DNS finds IP in database

3.  DNS returns IP

4.  If not found, DNS sends to higher level DNS

What items of data would be contained in a packet header?

-  sender IP address

-  packet number

-  packet size

-  number of packets

-  error detection method / value

each node directly connected to every other node. This lets a message be sent along many individual routes.