1.3.3 networks

• Client server model

  client server

  what are the advantages

  -more secure as data is stored in one location

  -central backups are carried out so no need for indivisual back ups

  -data and resources can be shared between clients
• Client server model

  client server

  what are the disadvantages

  -relatively expensive to set up

  -functuality of terminals depends on the server; if this fails so does performance

  -trained staff are required to maintain the server
• client server model

  client server

  what does this mean

  where device are reliant on services provided and managed by a central server

  -the server hols all of the important information and resources
• Network security and threats

  firewalls

  what are packet filters and what do they limit

  and how does it work

  the preconfigured rules

  they limit network access in accordance with administrator rules and policies

  it examines the source Ip, destination Ip and protocals used and ports requested
• Network security and threats

  firewalls

  what can firewalls have 2 of

  two network interface cards(NIC) between user and internet. then passes the packets between the two and compares them against the rules.

  -the preoccupied rules are called packet filters
• Network security and threats

  firewalls

  what is this

  this is a device desgined to prevent unauthorised access to a network
• Network Hardware

  Gateway

  what is this

  this is used protocoles between networks are not the same, it translates the protocols so that networks can communicate with each other
• Network Hardware

  Network Interface Cards(NIC)

  what does this mean

  this is a card required to connect a device to a network

  -this is built into the device and assigns a unique Media Access Control(MAC)
• Network Hardware

  routers

  what are they

  they are used to connect two or more networs together. Routers allow private, home networks to connect to internet
• Network Hardware

  Switch

  what is this

  this is a device to direct the flow of data across a network

  -mostly used in networks using a star topology
• Network Hardware

  what is MAC(media access control)

  is a 48 bit value coded into the deivce and is written as 12 digit hexadecimal number

  hexadecimal- is a number which uses number 0-9 and letters A-F
• Network Hardware

  Wireless Access Point(WAP)

  what is this

  device which allows a device to connect to a network, mostly combined with a router to enable internet access
• Network

  bus topology

  what does this mean

  and look like

  'is a type of network topology in which all devices are connected to a single cable called 'bus'
• Network

  bus topology

  what is the advantages

  -cheap to set up

  -don't need any additional hardware
• Network

  bus topology

  what is the disadvantages

  -if backbone cable fails the entire network gets disconnected

  -as traffic increases, performance decreases

  -all computers can see the data transmission
• Network

  Local Area Network(LAN)

  what is this

  this is the name given to a network which is spread over a small geographical area or a single site

  example:school
• Network

  Mesh topology

  what is a node

  a point of connection with in data communication
• Network

  Mesh topology

  what is the advantages

  -no cable cost(if wireless network)

  -as the number of nodes incease, the reliability and speed become better

  -nodes don't go through a central switch, improving speed
• Network

  Mesh topology

  what is the disadvantages

  -(if using wireless network) device with wireless capability can increase cost as they need to be purchased

  -if using wire, alot of cable is used than the other topology

  -maintaining the network is difficult
• Network

  Mesh topology

  what is this

  every node is connected to every other node, mostly found in wireless tech such as wifi
• Network

  Star topology

  what is the advantages

  -easy ro add new stations

  -if one cable fails, onyl that station is affected

  -performance is consistent even with hravy network traffic
• Network

  Star topology

  what is the disadvantages

  -expensive due to switch and cabling

  -if the central switch fails, the rest of the network fails
• Network

  Star topology

  what is this

  all nodes, indirectly connect to each other through one or more switches
• Network

  there are 2 types of main networks

  name them

  -Local Area Network(LAN)

  -Wide Area Networl(WAN)
• Network

  there are 2 types of network topology

  name them

  -physical topology

  -logical topology
• Network

  what is a topology

  how the computers are laid out and connected together
• Network

  what is it

  is the name given to 2 or more computers connected together with the ability to transmit data between each other

  such as: computers, printers, servers
• Network

  what is logical topology

  the layout which shows how data flows
• Network

  what is physical topology

  the physical layout of wires and components which form the network

  example: Bus, Star, Mesh
• Network

  what is protocol

  is a set of rules defining how two computers communicate with each other

  example:

  HTTP - used for web page rendering

  PO3 and IMAP - used for email access
• Network

  what is the purpose

  the main purpose is to enable data sharing, resource sharing, communication and collaboration
• Network

  Wide Area Network(WAN)

  what is this

  is the name given to a network which is spread over a large geographical area

  example: mostly used by large offices in multiple locations so they can communicate different sites
• peer to peer model

  peer to peer

  what does this mean

  a network in which computers are connected to each other so that they can share files

  -each device acts as a client and server, as it can both provide and request resources
• peer to peer model

  peer to peer

  what is the advantage

  -cheaper to set up

  -allows users to share resources

  -easy to maintain, specialist staff not needed

  -not dependant on central server
• peer to peer model

  peer to peer

  what is the disadvantage

  -backups must be performed seperately

  -poorer security

  -maybe difficult to locate resources
• network security and threats

  encryption

  what is this

  this is a way of keeping data secure when transmitting it over the internet
• network security and threats

  proxies

  what are the benefits

  -the privacy of user is protected and they remain anonymous

  -proxies can reduce overall web traffic
• network security and threats

  proxies

  what does this do

  what does it provide

  and what does it prevent

  -a proxy server collects and sends data on behalf of the user

  -it provides a gateway between users and internet

  -it prevents cyber attackers from entering private networks
• The Internet Structure

  Domain Name System(DNS)

  what are domains used to

  to access link to server across the world
• The Internet Structure

  Domain Name System(DNS)

  what are smaller domains seperated from large domains by

  by a full stop