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Data (Databases (Relational database (Relationships (One-to-many (Musk -…

- - - - One-to-many
        
        Musk - businesses
      - Many-to-many
        
        Player - items
      - One-to-one
        
        President - country
- - - - Ties up large area of network
      - Sends all in one route
      - All on same route, intercepted
      - Arrive in order sent
      - Establishes route for message duration
    - - Needs reorder
      - Own routes
      - No established route
      - Max use of network
      - No intercept
    - - Header
        
        IP addressees, protocol, number of packets, Time To Live
      - Trailer section, checksum (CRC)
        
        Detect errors, attaches hash from data and verified on other side
      - Payload
        
        Actual data in the packet
  - - - Use of routing algorithm, Dijkstra
  - - - Strip header data, new data added in format new network
  - - - Application
        
        Protocols relating to application
      - Transport
        
        TCP for end-to-end with recipient, split into packets w/number and port number
      - Network
        
        Adds IP from both ends. Port number and IP form socket, specifies device and app the packet is sent to.
      - Link
        
        Adds MAC address; identifies NIC from destination device.
      - When received:
        
        MAC, IP, port num stripped to reassemble in correct order
    - - High level protocol, in application layer
      - File management screen, dragging and dropping
    - - Post office protocol POP3
        
        Retrieving emails from temp mail server (deletes copy)
      - Internet message access protocol IMAP
        
        Keeps emails on server, syncs
      - Simple Mail Transfer SMTP
        
        Outgoing emails from one server to another, or from email client
  - - - Prevent unauthorised access to network, blocking connections
    - - Look at IPS from header, must be in "permitted list" for access.
      - Static filtering can block ports
    - - Hides network address from recipient
      - Keep cashe in case conncetion loss
      - Can filter requests by admin requirements
    - - Viruses and worms
        
        Viruses, needs to be executed to replicate/damage
        
        Worms replicate without executed
        
        Exploit "buffer overflow", writes to small locations and overwrites incorrect areas.
      - Trojan
        
        Hidden in file until executed, exploit backdoor, no replicate
      - Precautions
        
        Update anti-virus signature
        
        OS updates
- - - - Used once
      - Sender and receiver had key
    - - Binary value of first character in plain-text and first one-time pad char
- - - - Uses heap to store
      - Overflow if over max mem
      - Useful if data structure size isn't known
      - Append, remove, length, insert, search, pop
    - - Fixed size
      - Array can be used
        
        Size is pre-decided
    - - Items move up when data is removed (high processing time)
      - Variable with number of data items, and front and rear pointers, creates space at front
    - - Add item to rear
    - - Remove item from front, return it
    - - Check if empty
    - - Check if full
    - - When full, rear points points to last