Networks amd the internet Flashcards
what is a local area network
a network which consists of a number of computing devices on a single site or in a single businesses
what is a bus topology
where all computers are connected to a single cable. the ends of the cable are plugged into a terminator
advantages of bus topologies
cheaper to install as it requires less cable than a star topology and does not require any additional hardware
disadvantages of bus topology
- if main cable fails, network data can’t be transmitted to any of the nodes
- performance degrades with heavy traffic
- low security as all computers in the network can see all data transmissions
what is a physical star topology
one that has a central node, which may be a switch or computer, which acts as a router to transmit messages
advantages of a star topology
- if one cable fails, only one station is affected, so it’s easier to isolate faults
- consistent performance even when network is being heavily used
- higher transmission speeds give better performance than a bus network
- no problems with collisions as each station has its own cable to the server
- system is more secure as messages are sent directly to the central computer and cannot be intercepted by other stations
- easy to add new stations without disrupting the network
disadvantages of a star topology/network
- may be costly to install because of the length of cable required
- if the central device goes down, network data can no longer be transmitted to any of the nodes
what is the node connected to on a star topology
a central device , typically a switch
what does a switch do
it keeps a record of the unique MAC address of each device on the network and can identify which particular computer on the network it should send the data to
difference between physical and logical topology
- the physical topology of a network is its actual design layout
- the logical topology is the shape of the path the data travels in, and describes how components communicate across the physical topology
how can we make a star topology act like a bus one
- use a bus protocol
- Use a central device that acts as a simple hub instead of a switch
- Ensure that all devices connected to the hub share the same communication medium
- Implement a collision detection and handling mechanism, such as (CSMA/CD), to manage simultaneous data transmissions and collisions,
operation of a physical bus network
- data cannot be simultaneously transmitted in both directions (duplex transmission not possible)
- each station receives all network traffic
- the traffic generated by each station has equal transmission priority
what is an MAC address
an address which is assigned into a card and uniquely identifies a device
- 48 bits long and is written as 13 hex digits
used of mac addresses
tracking people
what is a client server network
- one or more computers nominated as server, other computers are clients
- client accesses resources from server
- centralised management of security
- resources cannot be accessed if server turned off
- hardware and software on servers can be optimised for providing services
advantages of a client-server network
- security is better since all files are stored in a central location and access rights are managed by the server
- backups are done centrally so there is no need for individual users to back up their data
- if there is a breakdown and some data is lost, recovery procedures will enable it to be restored
- data and other resources can be shared
- servers will be accessible at all times
disadvantages of client-server network
- expensive to install and manage
- professional IT staff are needed to maintain the servers and run the network
what is peer to peer network
- resources stored on each individual computer
- no centralised management of security
- each computer has equal status
- any computer can access resources from any other computer on the network
- management of security more difficult
- computers communicate directly with eachother
- no dependence on each other
advantages of peer to peer
- cheap and easy to set up
- easier to share files
- no centralised server, if one peer fails, others can still use the network
examples of when peer to peer is used
video on demand- hundreds of computers can be used to hold part of the video and share the load
- file transfer
- wireless printing
- bluetooth speakers
disadvantages of peer to peer
piracy
- no central management, updates for the software are harder
- file duplication
- peers may lose connection easily
why is peer networking used for piracy
because it’s impossible to trace the files which are being illegally downloaded
consequences of piracy
- the more movies that stolen and illegally downloaded, the fewer resources movie makers have to invest in new films
what is wifi
a local area wireless technology that enables you to connect a device to a network resources or to the internet via a WAP
how to connected to a wireless network
- a computer needs a wireless network adaptor
- all stations share a single radio frequency communication channel
- each station is constantly turned in on the frequency to pick up transmissions
- transmissions are received by all the stations within range of the WAP
- to connect to the internet , the WAP usually connects to a router
what is a station
the combination of computer and interface controller
why is serial transmission favoured over long distances
- eliminates the risk of desynchronisation
- bits are transmitted simultaneously and may arive at different times
what is a network
a collection of connected computers
describe the logical operation of a bus topology
A node broadcasts data
All nodes on the network receive the data;
A node examines the received data to check if it is the intended recipient;
- Nodes use a shared
transmission medium
how can bit rate be higher than baud
Bit rate can be higher than baud rate if more than one bit is encoded in each signal
change;
Explain the operation of a physical star topology
Every device is (directly) connected to a central switch
Every device sends data via the central switch
The switch sends packets of data to the intended recipient only
explain why the volatile environment must be saved before an interrupt is serviced
- so that the currently running process can be returned to
- as the interrupt will clear register values
why would peer to peer be suitable in a home
- small number of users
- likely that users trust each other
- will avoid additional cost of buying server
- no additional expertise to set up
