Studied by 18 people
Define network
A group of nodes that are linked together through a transmission media to allow for communication and the sharing of resources.
Name 4 features of a LAN
Small geographical area
Uses MAC addressing and switching for routing
Uses private infrastructure
Uses ethernet: wireless and UTP cables
Name 4 features of a WAN
Large geographical area
Uses IP addressing for routing
Uses public infrastructure
Can be wired or wireless: fibre optic or satellite/radio
Name 2 features of a VLAN
All devices appear to be on same LAN despite geographical distribution.
Software implemented and creates a virtual partition on hardware
What is a SAN
A secure, high-speed data transfer network that provides access to consolidated block level centralised storage.
What is a WLAN
Same as a LAN but the permissions allow for users to be mobile with devices as they are not restricted by cables
What is the internet
Decentralised global network which uses the TCIP/IP protocols to transmit data via various types of media.
What is the intranet
A collection of private networks used within an organisation
What is the extranet
Controlled private network allowing businesses to gain information without granting access to the organisations entire network
What does a VPN do
Uses the internet to allow remote access to a private LAN whilst encrypting the connection to thwart eavesdroppers.
How does a VPN work
Transmits data through a secure pathway (tunnelling) and anomalies ones IP address
What is a PAN
A network covering a very small area
Name three examples of a PAN(2 wireless and 1 wired)
USB, Blutooth and Wi-Fi
What are standards
Rules for data transmission which help with interoperability on network devices, and transmission with integrity and minimum latency
Why do we need standards
Without them, manufacturers of networks have no common grounds on building their systems.
What is tunnelling
Transmission of data through a secure pathway using packet encapsulation.
Name 4 components of a VPN
VPN software (client application)
VPN router
VPN server
Internet
Define protocol
Set of rules that determine communication across a network.
What do protocols define
The format and order of messages exchanged and the action taken on transmission of a message.
Payload definition
Data that is going to be sent
Define packet
A small unit of data used in network communication, they have a certain size
Name 5 functions of protocols
Ensure data integrity
Flow control
Congestion control
Deadlock
Error checking
Explain how protocols are necessary in ensuring data integrity
They manage the overall completeness, accuracy and consistency of data.
Explain how protocols are necessary in flow control
Makes sure that the sender is transmitting data at a rate at which the receiver can digest
Explain how protocols are necessary in congestion control
When a node carries too much data, network service quality can deteriorate, resulting in queuing delay, data packet loss and the loss of new connections. Protocols help to prevent this by using congestion control algorithms which take network capacity into account.
What does the term deadlock refer too?
When 2 nodes or processes are trying to access the same node simultaneously causing neither to be able to proceed
Explain how protocols are necessary in Deadlock
The relevant protocol stops both and re-queues them so that they can happen sequentially letting traffic flow.
What is error checking in a network
A method which detects noise or other impairments introduced to data during transmission
Explain how protocols are necessary in error checking
By making use of parity bits, bits at the end of a packet that are calculated to be either a 1 or 0.
Name 2 primary concepts which slow data transmission
Network traffic and Number of users
Why does more traffic = slow data transmission
More traffic = lower bandwidth available per user on network so slower upload download speeds.
Bandwidth
Total amount of data per second
Name 3 secondary causes of slow data transmission
Time of day, Distance, Infrastructure
How does infrastructure slow data transmission
If a network is not set up in a way that lets it develop, quality can be affected
Name 3 tertiary causes of slow data transmission on a network
Environmental issues (like temperature, interference, etc.),
Infrastructure limitations due to financial reasons (cheaper equipment)
The type of data being transmitted (large files)
How does the type of cabeling affect transmission on a network
Some types are subject to more or less resistance (copper vs fibre optic) or interference (WiFi)
Name 4 broadband WAN connections
DSL, Fibre Optic, 3G,4G
What is lossy compression usually used to compress
Multimedia such as audio, image and video
What is lossless compression usually used to compress
Text data files and images
Negatives of lossy
Irreversible and reduces quality
Negatives of lossless
The file is not as small as in lossy
Why is compression used ?
Reduces the time of transmission and optimises storage space.
What are the 4 types of media comparison points
Security, reliability, cost and speed
How good is the security of UTP
ok if encrypted
How reliable are UTP cables
Suseptible to electrical magnetic interferance
How much do UTPs cost
<ÂŁ1 per metre
How fast are UTP cables
100Mbps-1Gbps
How good is the security of Fibre Optic
Very secure, difficult to break in
How good is the security of Radiowaves(WLAN/WiFi)
Very insecure unless encrypted
How reliable are Fibre optic cables
Generally quite fragile
How reliable are Radiowaves(WLAN/WiFi)
Very susceptible to interference
How much do Fibre Optic cables cost
ÂŁ2-ÂŁ8 per unit
How much do radiowaves cost
Technically free but have to pay for service provider
How fast are Fibre optic cables
5-100 Gbps
How fast are radiowaves
5-200 Mbps
1st step of packet switching
A payload is split into smaller data packets (packetization)
2nd step of packet switching
The data packet is assembled with a header and tail, containing the IP addresses, sequence number and checksum
3rd step of packet switching
The packets are sent through multiple and optimal routes the the receiver
4th step of packet switching
Receiver re-orders the packet using the sequence number
5th step of packet switching
Receiver checks for lost and corrupted packets using the checksum
6th step of packet switching
The receiver requests a resend for corrupted or missing packets.
What does the header of a packet contain(packet switching)
IP address of sender/receiver nodes(or MAC if it is an internal network)
What does the tail of a packet contain(packet switching)
Sequence number for reordering packets at the receiver node and the checksum.
WAP
Allows for users to connect to a wireless network
Router
Maps out routes for data to follow, allowing transmission in a network
NIC
Holds the MAC address to identify nodes on a network
Name 3 pieces of hardware needed for a wireless network
WAP, Wireless router and a Wireless Network Interface card
Name 2 pieces of software needed for a wireless network
Software protocol stack and Network OS (specific for data transmission)
Name positives of a wireless network (5)
Flexible position of nodes(extended range/availability)
Easy to set up and maintain
Easy to add/remove nodes
Cheaper as there is no cabling
BYOD- bring your own device (companies don’t have to pay for infrastructure)
Name negatives of a wireless network (3)
Less secure so subject to interception
Slower data transmission than wired (As there is a lower bandwidth and channel interference)
Limited range-easily worsened by obstacles
Name characteristics of a wireless network (5)
No cabling
Uses radio waves as transmission media
Limited range
Needs specialist hardware/software to set up
Encryption is main mode of security
Give examples of types of wireless networks
WiFi- Radiowaves
WiMax- Microwaves(Longer range)
LTE Networks/ Mobile networks
4G- fast internet access
5G- Internet of things
What are the two security methods for wireless networks
Encryption and Authentication
What are the two encryption algorithms
WEP and WPA2
What is WPA2
WiFi protected access, encryption algorithm which makes data very secure as it has a longer encryption key
What is authentications role in Wireless network security
Used to gain access to the network, by verifying the user.
+/- of encryption
If one gains access to the private key then the algorithm isn’t effective
Longer keys = more secure
Encryption is reversible
+/- of Authentication
Secure access
Username+ Password can be shared/Stolen
Note 
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