1.3 Computer networks, connections and protocols Flashcards
Which network topology best describes The Internet?
The Internet is a great example of a partial mesh network. Packets on The Internet often take different routes to get to their destination. However, not all routers are connected to each other on The Internet.
The difference between a star network and a mesh network is that…
With a mesh network switches or routers are connected so there is more than one route to the destination.
What is a router
a piece of network hardware which sends data between networks
What is the purpose of the SMTP protocol?
sends email to an email server.
What does the internet protocol do (IP)
responsible for routing data across networks
What is the purpose of a Domain Name Server?
to maintain an index of mapped URLs to IP addresses and serve web pages
Which statement best describes ‘Ethernet’?
data is transmitted in frames on a local area network
what is latency
Which factor affecting the performance of a network is described as, ‘the delay from transmitting data to receiving it.’
what does a switch do and how is it specialised
.
What is a LAN
Local Area Network - a network of computers located over a small geographical area on a single site where all the hardware for the LAN is owned by the organisation using it
Common examples of a LAN
- school
- hospital
- offices
- flats
what are computers which are not connected to a network called
stand alone computers
what is a WAN
a WAN is created when LANs are connected. It spans over a large geographical area and the infrastructure between LANs is leased from telecommunication companies who own and manage them
common examples of a WAN
- mobile broadband
- internet
- a network of bank cash dispensers
What are the factors that affect the performance of networks
- number of users
- error rate
- transmission media
- bandwidth
- latency
How does error rate affect the performance of a network
less reliable connections mean that more errors occur when data is sent which then means that data needs to be resent until it arrives correctly.
what is latency
the delay from transmitting the data to receiving it
what is bandwidth
the amount of data that the medium can successfully send and receive over a given period of time
How does transmission media affect the performance of a network
Wired connections have a higher bandwidth than wireless
Fibre optic cables have a higher bandwidth than copper cables
how does having too many users affect the performance of a network
too many users or devices can cause the network to slow down if there is insufficient bandwidth for the data
what is the role of a server in a client-server network
- control access and security to one shared file store
- manages printing jobs and access to the internet
- runs a backup of data
- provides email services
what is the role of a client in a client-server network
- make requests to the server for data and connections
advantages of a client-server network
- easier to manage security file
-easier to take backups of shared data - easier to install software updates
disadvantages of a client-server network
- can be expensive to setup and maintain
- requires specialists to maintain
- server is a single point of failure
- users lose access if the server fails
what is a peer responsible for in a peer-to-peer network
- peers server their own files to each other
- responsible for their own backup and security
- usually have their own printers
advantages of a peer-to-peer network
- very easy to maintain
- specialist staff not required
- cheaper to set up
- no expensive hardware required
disadvantages of a peer to peer network
- less secure
- users need to manage their own backups and security
- can be difficult to maintain a well ordered file store
what 5 bits of hardware are needed to connect stand-alone computers into a LAN
- wireless access points
- routers
- switches
- Network Interface Card
- Transmission media
what does a router do
Uses IP addresses to route traffic between networks. Routers work by collecting knowledge of available routes to transmit data. They then determine the most suitable route for sending data.
You CANNOT connect to a WAN without a router
what does a switch do
- sends data between computers on a LAN
It learns the MAC addresses of all the devices connected and forwards the traffic in an intelligent way to the correct location only
what does a NIC do
- use a protocol to determine how the connection should work and allow devices to connect to either a wired or wireless network
what does a WAP do
allows wireless enabled devices to connect to a network
advantages of fibre optics
- cover much longer distances
- has a greater bandwidth than copper
how do fibre optic cables work
use light to transmit data
advantages of copper cables
- lightweight
- inexpensive
- easily installed
what does the DNS do
Domain Name Server - it takes the human friendly URL (www.abc.co.uk) and maps it to its IP address which the computer can then use.
It is a store of which IP addresses match up to which URLs.