Topic 2 -Data transmission

Question 1

how is data sent over long distances

Answer 1

broken uop into smaller parts, data packets,

Question 2

what does the data packet contain

Answer 2

header
payload
trialer

Question 3

header

Answer 3

IP address of sending , receiving device and sequernce number of packet

Question 4

payload

Answer 4

actual data

Question 5

trailer

Answer 5

method of identifying end of packet + some form of error checking

Question 6

what is packet switching and how it works

Answer 6

way of transmitting data.
message broken up into number of packets that can be sent indipendently, at the destination they will be reassambled in correct order
each packet will follow its own pathj based on traffic

Question 7

what routers do and why

Answer 7

determine which routye the packet needs to take, depends on n. of packets waiting to be processed at each node, shortes route always chosen

Question 8

advantages of packet switching

Answer 8

fast, efficient
high data transmission rate is possible
emails and text will work in a crisis or disaster
different speeds devices can communicate

Question 9

disadvantages

Answer 9

packets can be lost
this method only good for some type of data
there is a delay at destination (re-order)

Question 10

DATA TRANSMISSION

Answer 10

transmitting bits from one device to another

Question 11

serial transmission

Answer 11

less likely to do errors
slower, less efficient6
long distance

Question 12

parallel transmission

Answer 12

quicker, very effiecient
high error rate
short distance

Question 13

transmission mode

Answer 13

simplex= one direction
half duplex= both directions but one at the time
full duplex= both directions at the same time

Question 14

USB features

Answer 14

universal serial bus, serial data transmission form (half and full duplex)
4 wires,2 for power, 2 for data transmission

Question 15

USB advantages

Answer 15

standard in industry
error-free data transmission
easy to add more USB ports
devicesplugged in automatically detected

Question 16

USB disadvantages

Answer 16

max 5 metres
may not be supported by older computers

Question 17

when do errors occur in data transmission

Answer 17

interface
problems data switching
skewing of data
power surges

Question 18

what is parity check

Answer 18

extra bit added to ensure that n of bits is even or odd

Question 19

what is check digits

Answer 19

additional digit at the end of a string to check for mistakes, can be calculated using modulo 10 system

Question 20

checksum

Answer 20

block of data is sent alongside a calculated checksum value, receiving compoter calculates this value and the 2 values are compared to check fo error

Question 21

Automatic repeat requests(ARQ)

Answer 21

message sent to the sender indacating if data has been received correctly
tuime out= time allowed to elapse before an ackowlegmebnt is received