CHAPTER: COMMUNICATION & INTERNET TECHNOLOGIES Flashcards
1
Q
Protocols
A
- set of rules governing communication
2
Q
Why protocols are essential
A
- provides a standard set of accepted rules for transmitting and receiving data
- to enable communication between different platforms
3
Q
POP3/4 : Post Office Protocol
A
- download emails from server (4)
- a pull protocol that handles the receiving of emails (3)
4
Q
HTTP : HyperText Transfer Protocol
A
- access email in browser
- handles transmission of data to and from a website
5
Q
FTP : File Transfer Protocol
A
- handles transmission of files across a network
6
Q
SMTP : Simple Mail Transfer Protocol
A
- handles the sending of emails
7
Q
IMAP: Internet Messages Access Protocol
A
- downloading/recieiving emails (similar to POP3)
8
Q
TCP/IP Protocol Suite
A
- layer network model with 4 layers
- uses set of protocol for transmission of data
LAYERS: - application
- transport
- network/internet
- data link
9
Q
Application Layer:
A
- encodes the data being transferred
- encodes the data in the appropriate form (on sender’s side)
- receives messages performs operation required by sender (on reciever’s side)
10
Q
Transport Layer:
A
- data broken to packets and sent to network layer
- uses TCP protocol
- ensures packets arrive in sequence without any errors
11
Q
TCP Protocol
A
- uses positive acknowledgment with retransmission
- automatically resends data if packet acknowledgment is not received
- connection-oriented (connection is required for transmission)
12
Q
Network/Internet Layer:
A
- ensures correct routing of data packets over the internet
- takes the packet from the transport layer and adds its own header (IP address of sender and receiver)
- encapsulates data into datagram
- passes datagram to link layer for transmission on LAN
13
Q
Link Layer:
A
- protocols in layer to provide means to deliver data to other devices
eg; of protocols present - ethernet protocol
- WIFI protocol
- Bluetooth protocol
14
Q
Purpose of Packet holder:
A
- store data about packets and routing info so it reaches
- ensure message can also be reconstructed correctly
15
Q
Contents of TCP header:
A
- source port number
- ID Number
- sequence of packets
16
Q
Contents of IP header
A
- IP of sender
- IP of destination
- IP version
17
Q
Contents of IP data packet:
A
- message data
- size of packet
- source IP
- destination IP
- checksum
- protocol info
- sequence no. of packets
- IP version
18
Q
Bit Torrent
A
- allows fast sharing of files via P2P fule sharing
19
Q
How data shared in Bit Torrent
A
- torrent file is made available
- the file to be shared is split into pieces
- bit torrent client software is made available to other papers which allows them to work as seeds
- peer can acts as a seed and upload file
- another peer can download the file and can get different pieces of the file from other seeds simultaneously
- peers with downloaded files can become seeds
20
Q
Seed
A
- peer computer with 100% of file
21
Q
Swarm
A
- all connected peer computers have file parts to upload/download share torrent
22
Q
Tracker
A
- control/central server
- stores details of computers that have file to be downloaded
- shares IP addresses with other peers in swarm allowing them to control
23
Q
Leecher
A
a computer in the network that downloads more than it upload creating a negative impact on the swarm
24
Q
Circuit Switching
A
- circuit established at the start of the communication between the sender and the receiver
- lasts for the duration of call/file transfer
25
Packet Switching
- large message divided into equal groups of size called packets and each packet has a header and payload
- each packet is then dispatched independently and can travel along different routes
- they may arrive out of order but are then re-assembled to form original message (must wait for all messages to arrive before putting it back)
26
Router role
- examines packet header
- reads IP address of destination and uses the routing that router has access to and decides the next best route for packet
- sends the packet in the next hop
27
Benefits of Circuit Switiching
- real time
- better sync
- full bandwidth available
28
Drawback of Circuit Switching
- extra time to setup
- no alternate routes for data
- less secure and easy to intercept
- if route fails , entire transmission fails
29
Benefits of Packet Switching
- packets can be rerouted
- packets can take least congested route
- missing packets can be resent
30
Drawbacks of Packet Switching
- packets can be delayed
- unsuitable for realtime transmission
31
Why a company may use CS for voice calls
- dedicated channel and full bandwidth can be used
- two-way real-time communication
- no delay as no switching
- data arrives in the order it is sent
32
Why company may use PS for sending and receiving data
- asynchronous communication
- allows for error detection
- real time transmission not necessary
- smaller amount of data therefore high bandwidth or dedicated channel isn't required
33
What happens when there is a transmission from X to Y using Circuit switching
- X sends a connection request to Y
- Y sends ready or busy signal
- if busy X waits and resends request
- if available X sets the path between nodes
- X sends data, Y sends receipt signal
- sender then signals node to deallocate resources
34
LAN
Local Area Network
35
Switch
allows different netwrok to connect
36
Server
- provides medium for storage, sharing of files and application for its users
37
NIC's
- network interface cards
- consists of electronic circuitry required to communicate with other network/devices
38
