Topic 5 - Fundamentals Of Computer Networks Flashcards
What is a computer network ?
A computer network is a collection of computers linked together to facilitate communication and
the sharing of resources.
What are the reasons we would set up a network ?
data exchange
resource sharing
managing computers
what are some resources that can be shared ?
E.g. Printers.
E.g. Scanners.
E.g. Internet connections.
how can a network manager manage a network ?
Updating software.
Fixing problems.
Help users e.g. resetting passwords.
what factors affect the overall performance on a network ?
topology
wired vs wireless
bandwidth
choice of cabling
How does the topology of a network affect the overall performance of a network ?
The topology of the network (how the computers are laid out and connected together) can have a large impact on the network performance
How does wired vs wireless affect the overall performance of a network ?
Wired networks are usually much faster and more reliable.
Wireless performance depends on how well a computer can pick up the signal but is rarely better than a wired connection would be.
How does bandwidth affect the overall performance of a network ?
Bandwidth is the amount of data that can be transferred in a given time.
The greater the bandwidth, the better the network’s performance potential.
Bandwidth is shared between all active users, so performance can decrease if there are too many users.
How does choice of cabling affect the overall performance of a network ?
The choice of cabling and other networking hardware can have a big impact on the speed of a network.
what is Transmission media ?
Transmission media are different ways of physically transferring data along a network
What are the transmission media of wireless networking ?
Radio waves are the transmission media of wireless networking.
E.g. WiFi.
E.g. Bluetooth.
why does WiFi signal lose strength further away from a WAP ?
The amplitude (strength) of a radio wave decreases as it moves further from its transmitter.
Radio waves are also subject to interference from other radio signals of similar frequency
What do Wireless access points (WAPs) often check for before starting a broadcast ?
frequency channels that are least congested
what transmission media is most often used for cable televisions ?
Coaxial cable
What is a coaxial cable ?
a wired transmission media where an insulated copper wire is surrounded by a metal mesh to protect it from interference.
used for tvs
What are Fibre-optic cables made of ?
Fibre-optic cables are made of thin strands of glass which transmit binary data as pulses of light.
how do fibre-optic cables transmit binary ?
transmit binary data as pulses of light.
what are the advantages of fibre-optic cables?
Do not suffer interference.
Very high bandwidth (100Tbps).
why are fibre optic cables appropriate for long distance communication such as undersea cabling ?
Because of the lack of interference
What are Twisted-pair copper cable also known as ?
ethernet cables
why are the 8 wires in Twisted-pair copper cables twisted into pairs ?
This is to reduce interference from other signals and improve transmission speed.
fact
Twisted cables have different ratings to indicate how quickly data can be transferred.
E.g. Cat-5e can transmit at 1 Gbps.
E.g. Cat-6 can transmit at 10 Gbps.
what are 3 things network administrators can do ?
Update software
Fix problems
Help users
Will increasing the bandwidth always make a network faster ?
No
What is a WAN ?
wide area network
A WAN is a collection of computers connected over a large geographical area.
Who use WANs ?
WANs are used by multinational organizations that have international offices they need to connect to.
Why are WANs usually rented from large telecommunications companies ?
because WANs are expensive to set up.
What is an example of a WAN ?
The Internet.
The Internet is the largest WAN in the world.
What is PAN ?
A personal area network (PAN) is a network used to connect a single user’s devices in their workspace.
What is an example of a PAN ?
An example of a PAN would be connecting your phone to a headset via bluetooth.
what is a LAN ?
A local area network
A LAN is a collection of computers connected over a small geographical area.
When are LANs used ?
These are typically found in homes, schools, universities, and small companies.
who sets up and maintains a LAN ?
The LAN is set up and maintained by the organization that uses it.
what is WIFI ?
WiFi is a set of protocols that define how network devices can communicate wirelessly over radio waves
By creating devices which use the same standards, what can we guarantee ?
we can guarantee that devices from different manufacturers will be compatible.
What does the WiFi standard define?
What frequency radio waves should be
How powerful a transmitter should be
How data can be secured
What should happen if data is lost in transmission
why is it easier to intercept WiFi signals than signals in a wire ?
This is because they are just radio waves that anyone can pick up.
why is it important to protect against eavesdroppers ?
Because WiFi is so open, it’s important to protect against eavesdroppers.
what are three common security measures to protect against eavesdroppers ?
Wired Equivalent Privacy (WEP).
Wi-Fi Protected Access (WPA).
Wi-Fi Protected Access version 2 (WPA2)
why is WEP the weakest protection of all ?
WEP simply needs a password to join the network.
No data is encrypted, so it can be easily intercepted.
How does WPA work?
WPA also uses a password to join the network.
WPA also uses encryption to scramble the data being sent:
This means that only devices with the correct key can decode the data.
WPA is much stronger than WEP.
how does WPA2 work ?
WPA2 is the successor of WPA.
WPA2 uses a stronger encryption algorithm to prevent unauthorized parties from accessing the encrypted data.
In the star topology how are devices connected ?
each device is connected to a central switch or server
where is star topology common ?
In a LAN
Why is star topology used ?
Simultaneous access - The star topology allows many devices to access the server simultaneously (at the same time).
scalable - The network can easily be scaled up by adding more devices
reliability - If a single client fails, then all other clients can continue as usual.
What are the cons of star topology?
Expensive - It can be expensive to run a cable to every single device in a wired star.
Wireless star networks can sometimes be more cost effective.
Reliability- if the server fails, then the whole network is affected.
In the bus topology how are devices connected ?
each computer is connected to a main cable called the bus
What are the benefits of bus topologys ?
Cabling - The bus topology does not require many physical cables
Expansion - The bus topology is easy to build, and new computers can be added very easily.
What are the negativities of bus topologys ?
Troubleshooting - Problems with the network can be difficult to find, since a break in the main cable could have occured in any place.
Reliability - The bus topology is unreliable, since if the main cable is broken then the network is shut down completely.
