Networks (in order) Flashcards
(40 cards)
what is synchronous transmission
In synchronous transmission, streams of bits are transferred over a communication channel at a constant rate. The transmitter and the receiver are synchronised using a common clock signal.
what is asynchronous transmission
there is no clock signal, so additional data (start and stop bits) is used to control the communication. Data is transmitted when it is available, rather than at specific intervals. This means that there can be periods of time when the transmission channel is idle.
explain the start and stop bits in asynchronous transmission
a bit is sent to signal the start of a transmission
and another bit is sent to signal the end if the transmission the end bit is the opposite to the start bit and is typically longer so the receiver has time to reset for the next communication
where is synchronous transmission often used
its often used in parallel transmission as it can send more bits per unit of time (due to no start and stop bits)
where is synchronous transition often used
its often used in parallel transmission as it can send more bits per unit of time (due to no start and stop bits)
what is serial transmission
its where data bits are sent in a sequence, one after the other, over a single wire.
what is parallel transmission
is where several bits are sent at the same time over their own dedicated wires or printed circuit tracks
whats a negative of parallel transmission
its only reliable over short distances
why is parallel transmission only good over short distances
skew, crosstalk
whats at the middle of a star network
a switch
what are topologies
The different arrangements of computer connections and devices
what is a server
server is a program on a computer that shares resources with, or provides services to, any authorised client
what are the 2 network models
client to server and peer to peer
how does a client to server model work
1) The client submits a request through a network-enabled device.
2) The network server receives and processes the request.
3) The server delivers a response to the client.
how does a peer to peer network work
each computer acts as both a server and a client—supplying and receiving files—with bandwidth and processing distributed among all members of the network
pros of peer to peer
it doesn’t cost much to set up after you have the clients
less points of failure as if one client goes down the rest of the servers normally fine
cons of a peer to peer network
physical security- its less secure as there may be many locations where the sever can be accessed so harder to monitor
back ups - individual users are likely to be responsible for backing up their own data.
pros of a client server model
easy to back up as most important files are in one location
physical security is better as a server can be monitored easily
cons of a client sever model
expensive to set up
if the sever goes down many users can be affected as opposed to just the one in a peer to peer
how are wireless packets often encrypted
using one of these WEP, WPA, or WPA2.
what does WEP stand for
WEP (Wired Equivalent Privacy)
what does WEP do
It uses a symmetric encryption algorithm, meaning the same key is used to encrypt and decrypt data. It does have some weaknesses: WEP keys are often too short and used for too long, making them easier to decipher and more accessible
what does WPA stand for
WPA (WiFi Protected Access)
what does WPA do
introduced key management, which generates a new encryption key for each data packet. Larger keys also make the encrypted messages more challenging to decrypt
