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A Level Computer Science > 4.9 Fundamentals of Communication and Networking > Flashcards

4.9 Fundamentals of Communication and Networking Flashcards

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1
Q

Serial Transmission

3, 2Adv, 1Dis

A
  • one wire
  • one bit at a time
  • long (external) distances
  • simple to set up
  • cheap, reliable
  • slow transmission
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2
Q

Parallel Transmission

3, 1Adv, 2Dis

A
  • multiple wires
  • multiple bits transmitted simultaneously
  • short (internal) distances
  • faster transmission
  • less reliable (skew) (interference)
  • expensive

skew = bits arrive in the wrong order

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3
Q

Synchronous Data Transmission

4

A
  • data transferred a regular intervals on the rising edge
  • shared clock pulse
  • helps with skew
  • used for real-time data
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4
Q

Asynchronous Data Transmission

4

A
  • data sent as soon as it is ready
  • no shared clock pulse
  • start and stop bits (must be different)
  • parity bit (number of 1s)
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5
Q

Start Bit and Stop Bit (DEFINITION)

A

Start bit tells the receiver to prepare for data

Stop bit tells the receiver to get ready for the next sequence of data

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6
Q

Baud Rate (DEFINITION)

A

Baud Rate = The number of signal changes per second

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7
Q

Bit Rate (DEFINITION)

A

Bit Rate = The number of bits sent per second

bit rate >/ baud rate

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8
Q

Bandwidth (DEFINITION)

A

Bandwidth = The capacity that can be processed per second

shared amongst devices on the network

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9
Q

Latency (DEFINITION)

A

Latency = The delay between transfer of data and seeing the result

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10
Q

Protocol (DEFINITION)

A

Protocol = A set of rules for data exchange between devices

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11
Q

Bus Topology

2, 2Adv, 3Dis

A
  • all clients joined to one cable (backbone)
  • terminator at each end of cable to help reflect signals back

Adv:
- cheap to install (less cable)
- no additional hardware needed apart from main cable

Dis:
- poor security (all can see all transmissions)
- if main cable fails, network fails
- increased traffic = collisions

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12
Q

Star Topology

2, 5Adv, 2Dis

A
  • each device on a network has own cable to switch/hub
  • used when speed = priority

Adv:
- easy to add computers
- consistent high performance (despite traffic)
- more secure (straight to server)
- if fails, rest is fine
- no collision issues

Dis:
- whole network goes down if central node fails
- lots of cable = £££

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13
Q

Client-Server Network

2, 1Adv, 1Dis

A
  • data stored on dedicated server
  • all requests go to server and it allocated required resources back to requested computer
  • files and software can be stored securely on server
  • if server goes down, the network fails
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14
Q

Peer-to-Peer Network

2, 2Adv

A
  • no central server
  • all computers have equal status
  • communication without need for specialised hardware
  • if node goes down, network doesn’t fails
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15
Q

WiFi (DEFINITION)

A

WiFi is a wireless LAN based on international standards

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16
Q

WiFi - The Purpose

2

A
  • enables devices to connect to a network wirelessly
  • public WiFi = hotspots
17
Q

WiFi - The Hardware

3, 3

A

NIC
- allows device to connect to a wireless system
- located in device
- assigns MAC address

WAP
- allows wireless devices and wired networks to connect through a wireless standard
- located in router
- assigns IP address

18
Q

WPA/WPA2

4

A

WiFi Protected Access
- authentication
- passwords
- encryption
- prevents unauthorised access

19
Q

SSID

3

A

Service Set Identifier
- each network has a unique number
- must use same number to join the network
- broadcast can be turned off

20
Q

MAC Address White List

2, 1Adv, 1

A
  • list of users who can access
  • if user not on list, can’t join
  • very useful for security

no security measure stops users allowed on a network from obtaining malware and causing harm

21
Q

Firewalls (DEFINITION)

A

Firewall = a system that filters network traffic to protect against unauthorised flows of data in or out of the network

22
Q

Firewalls

3, 2

A
  • hardware or software
  • isolates network traffics
  • allows/denies based on IP address
  • stateful packet inspection
  • packet filtering
23
Q

Proxy Servers

2, 3Adv

A
  • act as ‘middle man’
  • data got from web server is then stored on proxy server
  • speeds up data access
  • secure (IP address hidden from web server)
  • proxy server sends data back after a while to free up storage
24
Q

Symmetric Encryption

2, 1Dis

A
  • 1 key for encryption & decryption
  • keys exchanged securely
  • easily decoded
25
Q

Asymmetric Encryption

4

A
  • 2 keys: 1 for encryption, 1 for decryption
  • Public key: everyone can see, used to encyrpt
  • Private key: only receiver has access, used to decrypt
  • extremely secure
26
Q

Protocols - Digital

1

A

secure data transfer uses SSL or TLS to encrypt

27
Q

Protocols - Human

1

A

some human protocols secure data e.g. password rules

28
Q

Digital Certificates

3

A
  • used when transferring data
  • ensures encrpted message is from trusted source
  • source will have certificate from certification authority
29
Q

Digital Signatures

2, 2

A
  • similar to real life signature
  • creates unique signature through:
    • mathemtical funcions
    • public and private keys
30
Q

Viruses

3

A
  • attaches to file to spread from one deivce to another
  • only works when ran/opened (executable file = typical)
  • same as worms
31
Q

Worms

5

A
  • spreads from device to device
  • self replicates
  • automatically sends itself to everyone in address book
  • exploits out of data sysmetsm ( no security update)
  • easily spread through lack of knowledge/awareness
32
Q

Trojans

3, 3, 2

A
  • appears useful/genuine
  • hidden harmful agenda
  • often creates backdoors
  • doesn’t infect other files
  • doesn’t self-replicate
  • don’t cause harm (hackers)
  • exploits human naivity
  • exploits with out of date anti-virus software

A Level Computer Science (10 decks)

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