topic 2 - communication and internet tech Flashcards Preview

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Flashcards in topic 2 - communication and internet tech Deck (21)
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1
Q

data transmission types (5)

A
  • simplex
  • duplex
  • half-duplex
  • full-duplex
  • serial
  • parallel
2
Q

simplex

A

data transmitted one way only

3
Q

duplex

A

data transmitted in both way

4
Q

half-duplex

A

data transmitted in both ways but not at the same time

5
Q

full-duplex

A

data transmitted in both ways at the same time

6
Q

serial(2)

A
  • one bit sent at a time over a single wire (eg. computer to printer)
  • used to send data externally between devices
7
Q

parallel (2)

A
  • multiple bits sent at the same time using multiple wires

- used to send data internally

8
Q

why use serial instead of parallel when connecting device to PC

A
  • single wire reduces the cost
  • single wire means less chance of corruption
  • more reliable over time
    bits still synchronised after transmission
9
Q

asynchronous transmission (2)

A
  • Data is sent in form of byte or character

- time interval of transmission is random

10
Q

synchronous transmission (2)

A
  • Data is sent in form of blocks or frames

- time interval of transmission is constant

11
Q

USB (7)

A
  • universal serial bus
  • data transmission method
  • uses serial transmission
  • device automatically detected
  • only fits one way; it cant fit incorrectly
  • industry-standard
  • backwards-incompatible
12
Q

methods of error-checking (4)

A
  • parity check
  • checksum
  • ARQ; automatic repeat request
  • check digit
13
Q

how does parity check work (5)

A
  1. checks byte of data
  2. a parity bit is added
  3. counts num of 1s
  4. can be odd or even
  5. if parity incorrect, error is detected
14
Q

when will parity check not work (2)

A
  • multiple errors in same byte
  • ## 2 bits interchanged
15
Q

how does ARQ (automatic repeat request) work (6)

A
  1. uses acknowledgement
  2. check performed on receiving data
  3. if error detected request sent to respond data
  4. resend request repeated until data sent correctly
  5. send an acknowledgement that data is received
  6. if acknowledgement not received in set time data is resent
16
Q

checksum (4)

A
  1. values calculated from the data
  2. it is transmitted with the data
  3. value recalculated after transmission
  4. values compared after transmission to check for error
17
Q

what is an IP address

A

location of a device on a network

18
Q

what is a MAC address

A

number that uniquely identifies a device

19
Q

what does https

A

hypertext transfer protocol secure

20
Q

describe what browsers do (3)

A
  • interprets HTML
  • URL entered into browser
    HTTP protocol used
21
Q

requesting web pages

A
  1. request
    - web browser used
    - url entered into browser
    - http protocol used
  2. sent
    - url contains domain name
    - domain name used to locate IP address
    - DNS server stores index of IP address and domain names
    - web browser sends request to web server
  3. received
    - data stored on wbeserver
    - web server sends data to browser
    - browser translate html