Networks (in order)

Question 1

what is synchronous transmission

Answer 1

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.

Question 2

what is asynchronous transmission

Answer 2

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.

Question 3

explain the start and stop bits in asynchronous transmission

Answer 3

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

Question 4

where is synchronous transmission often used

Answer 4

its often used in parallel transmission as it can send more bits per unit of time (due to no start and stop bits)

Question 5

where is synchronous transition often used

Answer 5

its often used in parallel transmission as it can send more bits per unit of time (due to no start and stop bits)

Question 6

what is serial transmission

Answer 6

its where data bits are sent in a sequence, one after the other, over a single wire.

Question 7

what is parallel transmission

Answer 7

is where several bits are sent at the same time over their own dedicated wires or printed circuit tracks

Question 8

whats a negative of parallel transmission

Answer 8

its only reliable over short distances

Question 9

why is parallel transmission only good over short distances

Answer 9

skew, crosstalk

Question 10

whats at the middle of a star network

Answer 10

a switch

Question 11

what are topologies

Answer 11

The different arrangements of computer connections and devices

Question 12

what is a server

Answer 12

server is a program on a computer that shares resources with, or provides services to, any authorised client

Question 13

what are the 2 network models

Answer 13

client to server and peer to peer

Question 14

how does a client to server model work

Answer 14

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.

Question 15

how does a peer to peer network work

Answer 15

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

Question 16

pros of peer to peer

Answer 16

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

Question 17

cons of a peer to peer network

Answer 17

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.

Question 18

pros of a client server model

Answer 18

easy to back up as most important files are in one location
physical security is better as a server can be monitored easily

Question 19

cons of a client sever model

Answer 19

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

Question 20

how are wireless packets often encrypted

Answer 20

using one of these WEP, WPA, or WPA2.

Question 21

what does WEP stand for

Answer 21

WEP (Wired Equivalent Privacy)

Question 22

what does WEP do

Answer 22

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

Question 23

what does WPA stand for

Answer 23

WPA (WiFi Protected Access)

Question 24

what does WPA do

Answer 24

introduced key management, which generates a new encryption key for each data packet. Larger keys also make the encrypted messages more challenging to decrypt

Question 25

what does WAP2 do

Answer 25

WPA2: an improvement on WPA that provides an even stronger encryption algorithm. Each message is encrypted several times, depending on the key size.

Question 26

what does SSID stand for

Answer 26

service set identifier (SSID)

Question 27

what does the SSID do

Answer 27

it allows a client to distinguish one network from another
The SSID often broadcast for all to see (however this can be a security risk so you can stop it from doing that it can still be found though)

Question 28

what is a WAP

Answer 28

wireless access point

Question 29

what are the 2 Frequency bands in a wireless network

Answer 29

2.4GHz
5.0GHz

Question 30

what does CSMA/CA stand for

Answer 30

carrier-sense multiple access with collision avoidance

Question 31

what does CSMA/CA do

Answer 31

CSMA/CA is a protocol used in wireless networking. It makes sure that network collisions (when two devices attempt to communicate at the same time) are avoided.

Question 32

how does carrier-sense in CSMA/CA work

Answer 32

The first step is to listen to the channel to check for the presence of any other signals. It is at this point that a decision is made whether to send the message or to try again at a later time.

Question 33

how does Collision avoidance in CSMA/CA work

Answer 33

Upon the detection of an existing transmission on a channel, the node that wanted to send will wait for a period of time before trying again.

Question 34

whats a node

Answer 34

an end device, which is either sending or receiving data across the network

Question 35

how does the transmission bit work in CSMA/CA

Answer 35

Once the channel is free, the data is sent. Then, the sender needs to receive an acknowledgement message from the receiver to verify that the data was received successfully. Otherwise, the sender will attempt to resend the message.

Question 36

whats the hidden node problem

Answer 36

this is where a devices is trying to check if a channel is clear however it can only do in its own range, so there could be a node that’s communicating but is outside of the devices range, making it a hidden node.

Question 37

what does RTS/CTS stand for

Answer 37

RTS- request to send
CTS- clear to send

Question 38

what instructions does RTS/CTS follow

Answer 38

check if channel is idle:
if False:
wait random time
else:
send request to send
wait for CTS
if received:
send Msg

Question 39

what does ISP stand for

Answer 39

internet service provider

Question 40

not a question but have 4.9.3.2 Internet security left on this and need to do 4.9.4 The Transmission Control Protocol/Internet Protocol (TCP/IP) protocol but gona do that in a diffrent thing as its such a big sub topic