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 eith by cable or wirelessly
- communication in 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.