4. Networks

4. Networks

Definition: Collection of computers and other hardware connected to allow the communication and sharing of resources
Network types
1. LAN
  1. Occupy an office or building
2. WAN
  1. e.g Internet
Advantages
1. Allow software to be installed
2. Communication: email,IM
3. Sharing resources
  1. Share file access
  2. Share printers
  3. Internet connection
4. Network management
  1. Access to files wherever you log in(LAN)
Devices
1. Router
  1. Enables connection between LAN and internet
2. Hub
  1. Where multiple computers can be connected by ethernet cables.
  2. Computers can communicate with eachother
  3. Allows internet connection to be shared
3. Switch
  1. Same as hub, Learns location of the computers and other devices plugged in
    1. More efficient(fewer unnecessary signals
4. Network interface card (NIC)
  1. Where ethernet cable plugged in
  2. Wireless signals recieved
Topology
1. Bus
  1. 2 Terminators
  2. Backbone
  3. Advantages
    1. Cheap/Minimal cabling
    2. Easy to remove computers
  4. Disadvantages
    1. Slowed by by highway network traffic
    2. Main cable fails-entire network fails
2. Star
  1. Single central device(switch?hub)
  2. Advantages
    1. Faults easy to find
    2. Easy to add extra devices
    3. System is secure as data is only sent to needed device
    4. If 1 cable fails only that device at end fails
  3. Disadvantages
    1. Lots of cable(expensive)
3. Ring
  1. Connected in a "circle"
  2. Advantages
    1. Very high rates of transmission possible
    2. No collisions
  3. Disadvantages
    1. Failure of single device or cable brings entire network down
    2. Security not ensured
Protocols
1. Used in communication between computers and their periphaerals and between computers across a network
2. Set of rules that computers mus follow in order for successful communication
3. HTTP(Hyper Text Transfer Protocol)
  1. Set of rules governing how hypertext is moved around the internet from device to device
4. FTP(File transfer Protocol)
  1. How files are moved from one computer to the other across the internet
  2. Relies upon building websites,moving files from developer's computer to a server, from which they can be accessed publicly
5. TCP(Transmission Control Protocol)
  1. Used by email and web pages to ensure data is sent securely and in an orderly way.
6. IP(Internet Protocol)
  1. Provides computer with its own unique address
7. Protocol Stack
  1. Combination of pieces of software that allow multiple protocols to be used on a single computer in the correct order
Networks Security Measures
1. Passwords
  1. Strong passwords
    1. Symbols,Numbers, upper/lower case words
2. User access levels
  1. Different access and privileges levels according to user
  2. Student: Manage own files
  3. Trainee network technician: Install software + student level access
  4. Network manager: Format drives, delete/create user accounts + Trainee access
3. Encryption
  1. Turns readable data into apparent nonsense
  2. Decrypted after sent over internet
  3. Encryption key
    1. Samll program that encyptes or decrypts data
Network Policies
1. Acceptable use
  1. Sets out what users are allowed to do and not allowed to do in a networj
    1. e.g Whether users can play games
    2. e.g What personal information should be entered into a network
    3. Without employees signing this they may break laws by accident and cause their company legal problems
2. Backup
  1. States what data will be backed up from the network,how often it will be backed up, where it will be stored and how it would be used to restore any lost data
  2. Data is less likely to be lost
3. Archive
  1. Long-term storage for data that is not needed on a day-to-day basis
  2. Archive policy will stipulate what data is to be achieved,where it will be stored and how old data needs to be before it is archived
  3. For legal reasons, organisations need to keep data for longer than it is useful to them
4. Disaster recovery
  1. Describes how an organisation's IT infrastructure will keep it running in the event of a disaster
  2. Contains parts of the backup and failover policies
    1. Important because an organisation without an IT capability is likely to lose income
    2. Loose people's trust in their ability to operate

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	Created by Asia Dixon~Nyah! almost 9 years ago