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A Level CIE CS 9618 Paper 3 > U14 communication and network tech > Flashcards

U14 communication and network tech Flashcards

1
Q

what is a protocol

A
  • set of rules
  • for successful transmission and receiving of data
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2
Q

why are protocols essential for communication between computers

A
  • provides a set standard for transmission of data
  • that basically gives accepted set of rules for transmitting and receiving data
  • enables communication between different platforms
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3
Q

POP3/4

A

post office protocol: downloads email from server

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4
Q

HTTP

A

hypertext transfer protocol: responsible for correct transfer of hypertext files

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5
Q

FTP

A

file transfer protocol: allows files to be transferred from one computer to another

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6
Q

SMTP

A

simple mail transfer protocol: responsible for sending emails

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7
Q

IMAP

A

internet message protocol: same purpose as POP/receiving mails but does not get deleted and can be accessed from different devices

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8
Q

bit-torrent

A

protocol used for peer-to-peer file sharing

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9
Q

TCP/IP protocol suite

A
  • conceptual model for networking
  • consists of 4 layers: application, transport, network, data link
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10
Q

application layer

A
  • sends files to transport layer
  • contains all programs that exchange data
  • e.g: web browser
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11
Q

transport layer

A
  • data is broken into packets and are sent to network layer
  • uses TCP
  • ensures that packets arrive in sequence
  • without errors
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12
Q

transmission control protocol

A
  • uses positive acknowledgement with re-transmission
  • automatically resends the data packets if it has not received positive acknowledgement
  • connection oriented (connection is required b/w devices => host-to-host)
  • re-transmits missing packets
  • re-assembles packets in correct order
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13
Q

function of TCP

A
  • allows application to exchange data
  • establishes and maintains connection until exchange of data is completed
  • determines how to break application data into packets
  • sends packets to and accepts packets from the network layer
  • manages flow control of data to avoid congestion
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14
Q

function of IP

A
  • ensures correct routing of packets of data over the internet
  • takes a packet from your transport layer and adds its own header, including IP address of both recipient and sender
  • encapsulates data into datagram (felt cute might delete later)
  • passes datagram to the link layer for transmission on the LAN
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15
Q

purpose of packet header

A
  • to store data about packet
  • and its routing to ensure that it reaches its destination
  • to ensure that messages can be properly reconstructed
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16
Q

contents of TCP header

A
  • source port number
  • sequence of packets
17
Q

contents of IP header

A
  • IP address of sender
  • IP address of destination
  • IP version
18
Q

IP data packet contents

A
  • message data
  • IP version
  • size of packet
  • sequence number
  • source IP address
  • destination IP address
19
Q

link layer

A
  • protocols in this layer provide the means for the system to deliver data to the other devices
  • ethernet protocol, wifi protocol, bluetooth protocol
20
Q

function of swarm

A
  • all the connected peer computers
  • that have all or part of the file to be uploaded/downloaded
  • they share a torrent
21
Q

tracker

A
  • central server
  • stores details of other computers that have all/part of files to be downloaded
  • store IP addresses of other peers in swarm allowing them to connect
22
Q

leechers

A
  • peers who download much more data
  • and upload less data
  • negative impact on network
23
Q

data exchange using bit-torrent

A
  • torrent file is made available
  • file to be shared is split into pieces
  • bit-torrent client software is made available to other peers which allows them to work as seeds or leeches
  • once a peer has a piece of a file it can become a seed for the parts downloaded and leeches download much more than they upload
  • tracker keeps record of all the peers and the parts of the file they have and can pause and restart at any time
24
Q

packet switching

A
  • a circuit does not have to be established at the start of communication
  • data to be sent is divided into packets
  • can travel different routes
  • from node to node
  • packets are reassembled in the correct order at the receiver’s end
  • must wait until the last packet is received to put the data back together
25
Q

circuit switching

A
  • dedicated communications channel b/w 2 communicating devices
  • a circuit is established at the start of the communication
  • between sender and receiver
  • lasts for the duration of the call/data transfer
  • the link that makes up the circuit is then removed
26
Q

packet switching pros

A
  • packets can be re-routed if there are problems
  • packets can take the least congested route
  • transmission error can be detected
  • missing packets can be resent
27
Q

packet switching cons

A
  • packets can be delayed
  • a real time conversation is not possible
28
Q

pros of circuit switching

A
  • person communicating can see each other in real time
  • better synchronization // full bandwidth available
29
Q

cons of circuit switching

A
  • bandwidth // channel not available to other users
  • extra time required to set up circuit at start of conversation
  • alternative route not available without restarting the conversation
  • less secure as easier to intercept data if only one channel is used
  • failure in single route used means failure of transmission
29
Q

server

A

central computer that stores all files to be downloaded

29
Q

command

A

ensures that user can send instructions such as delete, copy which are carried out on the server

30
Q

anonymous

A

allows user to access files and user does not need to identify themselves to the server

31
Q

network layer

A
  • ensures correct routing of data over the internet
  • takes a packet from transport layer and adds its own header which includes the IP address of sender and recipient
  • encapsulates data into datagram
  • passes datagram to datalink layer for transmission on the LAN
32
Q

data link layer

A
  • protocols in this layer provide the means for the system to deliver data to other devices
  • ethernet protocol, wi-fi protocol, bluetooth protocol

A Level CIE CS 9618 Paper 3 (6 decks)

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