Networks Flashcards
Define
network.
an arrangement of two or more computers that are connected together for the purpose of sharing resources and data
What are some advantages of a
network?
(5)
they allow multiple users to:
- share data files with each other
- share hardware devices (e.g. printers, speakers)
- share an internet connection and internet services (e.g. www and email)
- communicate with each other (e.g. email, messaging)
- work together using web-based software (e.g. shared calendars, virtual meetings)
What is the
internet?
the world’s largest public WAN, a global system of interconnected networks, linking together billions of digital devices worldwide
What are some characteristics of
LANs?
- geographic area?
- ownership?
- security?
- speed?
- cost?
- topology?
- type of addressing?
- hardware forwarding packets?
- small
- private individuals
- more secure
- slower cables but many less users
- cheaper as there is less hardware required
- bus or star or mesh
- MAC addressing
- switch
What are some characteristics of
WANs?
- geographic area?
- ownership?
- security?
- speed?
- cost?
- topology?
- type of addressing?
- hardware forwarding packets?
- large
- businesses and organisations
- less secure
- faster cables but shared amongst millions of connections
- more expensive
- partial mesh
- IP addressing
- router
What is a
node?
a device on a network
What is a
network topology?
how different nodes on a network connect to one another
What does a
bus topology consist of?
(3 key points)
- all the nodes on the network are connected to a single cable, known as the backbone
- messages are sent along the cable in the form of electronic signals
- a terminator at each end absorbs signals that have reached the end of the cable (preventing them from bouncing back and causing interference)
What are the advantages of a
bus topology?
(3)
- relatively inexpensive to install since very little cabling is needed
- if one node fails, the rest can still communicate with each other
- easy to add extra devices to the network
What are the disadvantages of a
bus topology?
(3)
- if the cable is cut or damaged the whole network stops functioning
- the more devices that are added, the more collisions will occur and the slower the network will run
- all nodes on the network ‘see’ all data traffic (this may be a security risk)
What is an example of a use of a
bus topology?
small, short-term networks
What does a
star network consist of?
(2 key points)
- every node is connected to a central node (likely a switch)
- all data traffic passes through the central node, which is responsible for routing to its destination
What are the advanatges of a
star topology?
(5)
- if one node goes down, the rest of the network will continue functioning
- a damaged cable doesn’t stop the network from working, just the device connected to it
- data traffic is only sent to the intended recipient and not passed through any other nodes (making it secure)
- it is easy to locate faults
- nodes can be added and removed without having to take the entire network offline
What are the disadvantages of a
star topology?
(3)
- if the central node fails, then the rest of the network stops functioning
- network performance and maximum number of nodes depends on the capacity of the central node
- a lot of cabling is required, making it difficult and expensive to set up
What is an example of a use of a
star topology?
home networks
What does a
mesh network consist of?
(2 key points)
- each node is connected to multiple other nodes either by cable or wirelessly
- communication is peer-to-peer (P2P) as there is no central controlling device
What are the advantages of a
mesh network?
(4)
- very fault tolerant - if one node fails, messages are rerouted
- nodes can be added and removed without having to take the entire network offline
- very scalable, any number of additional nodes can be added
- very high performance
What is the disadvantage of
mesh networks?
a wired mesh network is difficult and expensive to install
What is the
structure of the internet?
(4 levels)
- Every device connected to the internet is part of a network.
- Local networks connect to the internet via a Point of Presence (POP) (provided by an Internet Service Provider (ISP)).
- The ISP’s network is connected to a high-level network owned by a major telecommunication company (BT in the UK).
- Network Access Points (NAPs) interconnect the internet backbones to form a worldwide network.
What are some examples of
Internet Service Providers?
(3)
- Virgin Media
- BT
- Sky
What do
routers do?
(2)
- forward data from one network to another across the internet from source to destination
- keep each other up to date about traffic conditions in their part of the network, so that data can be routed away form congested areas
What is
IP?
and what does it stand for?
a set of rules governing data transfer on the internet
internet protocol
What do
IP addresses do?
uniquely identify devices on a network
What does an
IPv4 address look like?
13.255.182.0
(each of the four bytes is expressed as a decimal number between 0 and 255 separated by dots)