4.9 Fundamentals of Communication and Networking Flashcards
Serial Transmission
3, 2Adv, 1Dis
- one wire
- one bit at a time
- long (external) distances
- simple to set up
- cheap, reliable
- slow transmission
Parallel Transmission
3, 1Adv, 2Dis
- multiple wires
- multiple bits transmitted simultaneously
- short (internal) distances
- faster transmission
- less reliable (skew) (interference)
- expensive
skew = bits arrive in the wrong order
Synchronous Data Transmission
4
- data transferred a regular intervals on the rising edge
- shared clock pulse
- helps with skew
- used for real-time data
Asynchronous Data Transmission
4
- data sent as soon as it is ready
- no shared clock pulse
- start and stop bits (must be different)
- parity bit (number of 1s)
Start Bit and Stop Bit (DEFINITION)
Start bit tells the receiver to prepare for data
Stop bit tells the receiver to get ready for the next sequence of data
Baud Rate (DEFINITION)
Baud Rate = The number of signal changes per second
Bit Rate (DEFINITION)
Bit Rate = The number of bits sent per second
bit rate >/ baud rate
Bandwidth (DEFINITION)
Bandwidth = The capacity that can be processed per second
shared amongst devices on the network
Latency (DEFINITION)
Latency = The delay between transfer of data and seeing the result
Protocol (DEFINITION)
Protocol = A set of rules for data exchange between devices
Bus Topology
2, 2Adv, 3Dis
- 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
Star Topology
2, 5Adv, 2Dis
- 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 = £££
Client-Server Network
2, 1Adv, 1Dis
- 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
Peer-to-Peer Network
2, 2Adv
- no central server
- all computers have equal status
- communication without need for specialised hardware
- if node goes down, network doesn’t fails
WiFi (DEFINITION)
WiFi is a wireless LAN based on international standards
WiFi - The Purpose
2
- enables devices to connect to a network wirelessly
- public WiFi = hotspots
WiFi - The Hardware
3, 3
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
WPA/WPA2
4
WiFi Protected Access
- authentication
- passwords
- encryption
- prevents unauthorised access
SSID
3
Service Set Identifier
- each network has a unique number
- must use same number to join the network
- broadcast can be turned off
MAC Address White List
2, 1Adv, 1
- 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
Firewalls (DEFINITION)
Firewall = a system that filters network traffic to protect against unauthorised flows of data in or out of the network
Firewalls
3, 2
- hardware or software
- isolates network traffics
- allows/denies based on IP address
- stateful packet inspection
- packet filtering
Proxy Servers
2, 3Adv
- 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
Symmetric Encryption
2, 1Dis
- 1 key for encryption & decryption
- keys exchanged securely
- easily decoded
Asymmetric Encryption
4
- 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
Protocols - Digital
1
secure data transfer uses SSL or TLS to encrypt
Protocols - Human
1
some human protocols secure data e.g. password rules
Digital Certificates
3
- used when transferring data
- ensures encrpted message is from trusted source
- source will have certificate from certification authority
Digital Signatures
2, 2
- similar to real life signature
- creates unique signature through:
- mathemtical funcions
- public and private keys
Viruses
3
- attaches to file to spread from one deivce to another
- only works when ran/opened (executable file = typical)
- same as worms
Worms
5
- 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
Trojans
3, 3, 2
- 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
