Topic 5 - Computer Networks Flashcards
What is a computer network?
Multiple devices connected together that can share resources
What are the advantages of a network?
Share resources, data and peripherals
Centralised back-ups
Centralised updates
Centralised security
Connect globally
User monitoring
What are the disadvantages of a network?
Expensive to set up
Requires specialists skills
Viruses spread through connections
Less secure
Explain the peer-to-peer model
Each device acts as a client and a server
What are the advantages of the peer-to-peer model?
Not dependant on single server
Cheap to set up
Resources easily shared
Fast -can request from closest device
What are the disadvantages of the peer-to-peer model?
Sharing peripherals slows down if too many requests
No centralised back-ups
No security
Explain the client server model
Client makes requests, server fulfils those requests
What are the advantages of the client server model?
Files stored on central serve
Client breaking won’t affect network
Centralised back-ups
More secure
What are the disadvantages of the client server model?
Expensive to set up
Requires specialist skills
If serve fails, network fails
Suspectable to hacking
What does PAN stand for?
Personal Area Network
What does LAN stand for?
Local Area Network
What does WAN stand for?
Wide Area Network
What is PAN used for?
A single user with multiple device
ie. smart watch and phone
What is LAN used for?
Multiple users in a single building
ie. small office
What is WAN used for?
Multiple devices connected across a large geographical area (sometimes multiple LAN’s)
ie. Large companies in multiple countries
What is a Wireless Access Point?
A device used to connect devices to a wired network ie internet
What does a router do?
It moves data from one network to another
Connects networks to the internet
What does a switch do?
It is responsible for connecting data to the right device in wired connections
What does a hub do?
Broadcasts data to all connected devices
What does a Network Interface Card do?
Enables a wired connection between a computer and networked devices
What does a Network Interface Card contain?
MAC address
What does a bridge do?
Connects two LAN’s together to reduce traffic
What is a MAC address?
A unique physical address used to locate devices on a network
How does a star topology work?
The central node represents a hub or switch
How does a bus topology work?
All nodes are connected on a single cable, data is sent to all nodes in both directions.
The terminators stop signals from being deflected back down the cable
How does a ring topology work?
Data is transferred in one direction to all nodes
How does a mesh topology work?
The most efficient route to transfer data is calculated
What are the advantages of the star topology?
Damaged link only affects one node
Easily add new nodes
Works well under heavy load
What are the disadvantages of the star topology?
Central node failing affects all nodes
Expensive due to cabling
What are the advantages of the bus topology?
Cheap - 1 cable
Simple to set up
Works well for small networks
What are the disadvantages of the bus topology?
Cable fail = network fail
Not secure - data transferred to all nodes
More nodes = reduced performance
What are the advantages of the ring topology?
Additional nodes don’t decrease performance
Fast data transmission
No data collision
Works well under heavy load
What are the disadvantages of the ring topology?
One node fail = network fail
Unsecure - data transferred to all nodes
Slow
Network has to be shut down to add node
What are the advantages of the mesh topology?
No single point of failure
Fast
New nodes added easily
Works well under heavy load
What are the disadvantages of the mesh topology?
Expensive due to cabling
Complicated to manage and maintain
What is transmission media?
Media used to transmit data from one device to another
How does a copper cable work?
It used electrical signals to transmit data
What are the advantages of copper cables?
Cheap to buy & install
More stable than wireless
Good for short distances
What are the disadvantages of copper cables?
Signal degenerates over distance
Slower than fibre optic
Prone to disturbances
Costly to expand
How does fibre optic work?
Uses light pulses to transmit data
What are the advantages of fibre optic?
Good for long distances
Fast
Less prone to disturbances
Stable
What are the disadvantages of fibre optic?
Expensive to buy & set up
Costly to expand
How does WiFi work?
It uses radio frequencies to connect devices to networks and the internet
What are the advantages of WiFi?
Transmit 50m
Multiple users
Cheap to expand
Portable
Cheap to install
What are the disadvantages of WiFi?
Prone to hacking
Distance decreases connectivity
Susceptible to interference
More devices = speed decreases
How does Bluetooth work?
Uses radio frequencies to transmit data
What are the advantages of Bluetooth?
Reduced interference
Cheap
Uses less power then WiFi
Portable
What are the disadvantages of Bluetooth?
Only transmit 10m
Vulnerable to hacking
Limited number of devices at one time
Slower than WiFi
What are the 4 factors that affect the speed of a network?
Bandwidth
Latency
Range
Number of devices
What is bandwidth?
The amount of data that can be transferred in a specific amount of time
What is latency?
The delay from the time a signal is sent to when it is received
What is range?
The maximum distance a signal can travel before its quality is lost
How does the number of devices affect the speed of a network?
Each device take some of the bandwidth available
What is the internet?
Global network of networks
Infrastructure used to share data and resources globally
What is the World Wide Web?
A collection of web pages
What is a protocol?
A set of rules for communicating
What is an IP address?
A set of unique numbers given by an internet service provider very time you go onto the internet
What is the URL?
A user friendly way of writing the IP address of the server that stores a website
What is the DNS?
Domain Name System
Links website address with IP address
Explain the 4 steps of DNS
1) Checks if you have visited the website before
2) Web browser connects with web server at IP address supplied by DNS
3) Web browser request webpage, server sends HTML page
4) Browser builds web page using HTML
What is Ethernet?
A family of protocols used in a wired network
What is WiFi? (Protocol)
A suite of protocols which enables the transmission of data through radio signals
What does UDP do?
Breaks data into packets and re-orders them at destination, without error checking
What is the difference between UDP and TCP?
TCP uses error checking
When is UDP used?
Streaming
Gaming
What is HTTP/S?
Hypertext Transfer Protocol
Identifies requests and transfers web pages
HTTPS is more secure
What is FTP?
File Transfer Protocol
Uploads & downloads files from a server
What is an advantage of FTP over HTTPS?
FTP allows for more control
What is POP?
Post Office Protocol
Retrieves and email from the sever & deletes email on the server
What is IMAP?
Internet Message Access Protocol
Retrieves email from server but leaves a copy at the server
What is SMTP?
Simple Mail Transfer Protocol
Sends emails to an email server
What does TCP do?
Breaks down data into packets and reorders them at the destination
What does IP do?
Makes sure data arrives at the correct destination
What is TCP/IP?
A suite of protocols that transmits data over the internet
What is the first layer of TCP/IP?
Application layer
Prepares data for sending & decodes received data
HTTP/S, FTP, IMAP, POP, SMTP
What is the second layer of TCP/IP?
Transport layer
Accept messages, splits it into segments and allocates ports
TCP, UDP
What is the third layer of TCP/IP?
Internet layer
Receives segments and packages them into IP packets which include sender and receivers address
IP
