3. Communication Flashcards
What is a network?
A network is a collection of connected computers. These computers can communicate by sending data to each other.
What are the advantages of networks?
- computers in the network are able to share resources, such as printers and internet access
- data can be accessed from any and all computers within a network
- its easy for the manager to monitor network activity and control security
What is a LAN?
LAN stands for local area network. This is when the computer systems are located fairly close to each other, such as in a school or a building.
What is a WAN?
WAN stands for wide area network. This is when the computer systems are distant for each other, such as in different buildings or even different countries. The internet is an example of a WAN. Multiple LANS can be connected using a WAN.
What are the disadvantages of networks?
- hackers can more easily gain access to data
- viruses could be spread between computers
- if the server is shutdown, all devices are affected
What is topology?
The topology of a network is how computers are laid out and work together
What is bandwidth?
The amount of data that can be transferred in a given time. It is shared between all active users in a network, so if there are too many users then performance can decrease.
What are the four main network topologies?
- bus
- ring
- star
- mesh
What is a packet?
A packet is a collection of data sent on a packet-switching network. The computer system checks the packet’s destination address to see if it matches its own. If it does not, the computer system redirects it back along the network, and if it does, it processes the data. Data may be split into multiple packets, in which case it will be reassembled when it reaches its destination.
What is a bus topology and what are its advantages and disadvantages?
A bus topology is when all nodes of a network are connected by a single cable called a bus. There are terminators on either end of the cable to ensure that the network functions correctly. Packets are carried along the cable to each computer system.
ADVANTAGES
- easy to add more nodes
- quick to set up
- cost effective as there is not much cabling
DISADVANTAGES
- difficult to trouble shoot the bus
- limited cable length
- if there is a problem with the main cable, the whole network goes down
- data collisions are more likely (when two computers try and send a packet simultaneously)
What is a star topology and what are its advantages and disadvantages?
Each computer system is connected to a central node/hub.
ADVANTAGES
- fast network speed
- easy to set up and add new nodes
- any non central failure will not affect the rest of the network
- better security
- minimal data collisions
DISADVANTAGES
- expensive to install as there is lots of cabling
- extra hardware required, e.g. the hub
What is a ring topology and what are its advantages and disadvantages?
Nodes are connected in a ring/loop. Packets are sent around the loop until it reaches its destination.
ADVANTAGES
- data is quickly transferred as there is no bottleneck
- transmission of data is simple as packets only move in one direction
- additional nodes have little effect on bandwidth
- prevents network collisions
DISADVANTAGES
- if a computer system fails, the ring is broken and the data cannot be efficiently transmitted
- you must temporarily shut down the network to add a new node as all nodes are connected
- difficult to troubleshoot
What is a mesh topology and what are its advantages and disadvantages?
A mesh topology is when every computer system in the network is directly connected to each other.
ADVANTAGES
- fast network speed
- new nodes can be added with no disruption to the network
DISADVANTAGES
- impractical as there are many connections required
- a lot of maintenance is required
How do you connect a computer system to a network.
The computer system requires a network interface card (NIC). It can be connected either physically via fibre optic cables (faster) or copper cables (slower), or wirelessly via Wi-Fi. wi-Fi speed varies depending on distance and atmospheric conditions.
What is circuit switching?
When a temporary but dedicated link is established between two devices. No other data can be transmitted along the same route during the connection. Once the connection is established, it is fast and reliable, but the connection can take time to establish. An example of circuit switching is the landline telephone system.
