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Topic 1.3 Network - Coggle Diagram

- - - - Full-Mesh
        
        Advantages
        
        Self-healing
        
        If a cable breaks the data will take a different path
        
        Easier to set up
        
        Disadvantages
        
        apart from lower speeds due to it being self-healing it is hard to find problems
        
        Very expensive to set up due to the amount of cables and servers required
        
        Every device is connected to every other device. There is no central device and a good example is the Internet
      - Star
        
        Disadvantages
        
        Is not self-healing so device will go down if a cable is broken
        
        harder to set up
        
        devices are arranged around a central switch/hub.This allows all devices to access the server efficiently. There are fewer data collisions then a bus or ring networks and will only fail if the switch breaks.
        
        Advantages
        
        Very easy to find problems as either one device is down or the whole network is
        
        Cheaper to build and replace due to little amount of cabling required
  - - - Transport
        
        FTP
        
        Controls the sending of files through use of the FTP protocol
      - Network
        
        TCP
        
        Splits the Data into packets and adds the error check and sequence number to the packet header
      - Application
        
        HTTPS,HTTP,SMTP,IMAP,POP
        
        Encodes the data being sent and controls the sending and receiving of websites/ information over the internet like emails through the use of web browsers and email clients
      - Link
        
        Assigns the IP and MAC address to each packet of the sender and destination
        
        IP
  - - - POP
        
        Retrieves emails from a mail server. Emails are downloaded and deleted from the server on user access
      - IMAP
        
        Retrieves emails from a mail server. Emails are downloaded by the client but are NOT deleted from the server unless the user does so.
      - SMTP
        
        Protocol to manage the sending of emails
    - - HTTP
        
        Used by web browsers to access websites. Allows the browser to communicate with the a web server
      - HTTPS
        
        A secure/encrypted version of HTTP
    - - IP
        
        Adds the Sender and destination IP address
      - TCP
        
        Splits data into packets and adds the error check and sequence number
      - FTP
        
        Transmits files across a network
- - - - Use light to transmit data across much longer distances then copper and with greater bandwidth
      - The backbone of the Internet uses fiber optic cables for fast speeds.
    - - Wired connections that assure maximum bandwidth, security and reliability.
      - They use twisted pair cables (wires twisted around each other) to avoid interference. There is usually one cable for receiving and one for sending
    - - Unshielded Twisted Pair
    - - insulated copper wire; used to carry high-speed data traffic and television signals
      - Examples
        
        (e.g. to TVs , freeview boxes or ariels)
  - - - Old
        
        Old ethernet cable is a backbone cable which uses a protocol called CSMA/CD
        
        needed to listen for A communication before transmitting and detecting when two computers transmit at the same time
      - New
        
        A twisted cable duplex is possible (sending and receiving at the same time).
        
        The CSMA/CD protocol is not needed as frames cannot collide
      - What is it
        
        is a standard for wired networks
- - - - What is encryption
        
        The process of using a key to scramble data
      - symmetric
        
        public key encryption, only one key is shared
      - asymmetric
        
        Where a pair of keys called the private and public keys is used
        
        public key- is given to anyone and can encrypt data but not decode it
        
        private key- is only given to the sender of the data and can decode data. This key is not given to anyone
  - - - advantages
        
        Data can be shared between people who are not geographically close
        
        Data can be stored centrally, this means it can be shared and backups can also be done centrally on any device
        
        Data can be transferred easily
        
        Security and anti-virus can be controlled centrally
        
        Users can be controlled
        
        Peripherals can be shared
      - disadvantages
        
        networks are hard to keep working and sometimes complex
        
        Networking means devices are vunerable to cyberthreats including hacking
    - - Wireless(WIFI)
        
        advantages/disadvantages
        
        advantages
        
        Unlike wired new nodes can be easily added without disruption
        
        Unlike wired, users can go from room to room
        
        Unlike wired, doesn't required you to buy and fit in cords so is easy to add users
        
        disadvantages
        
        WIFI signals can suffer from electromagnetic interference from other devices or signals
        
        WIFI can be blocked by obstructions such as walls leading to dead spots.
        
        WIFI signals only have a certain range (usually 50 meters)
        
        Each WAP only has so bandwidth it can share among connected nodes. The more connected the slower performance and connection becomes
        
        WIFI signals are risky as the frequency can be easily intercepted by unauthorised users. To fix this signals are encrypted.
        
        What is WIFI
        
        A standard for wireless connections
        
        frequency/ channels
        
        5GHz
        
        the lower hertz means that you can't go as far as 2.4GHz without performance issues.
        
        Due to having only one channel there is no overlapping frequencies
        
        A frequency that only has one channel so if multiple users are connected transmissions may infer with each other
        
        2.4GHZ
        
        The higher hertz allows for a further distance without performance issues
        
        although due to overlap in the channels multiple users may disturb the channels causing interference.
        
        A frequency that allows for multiple users to go through at once through the multiple channels
        
        How does a WAP use a Channel
        
        WAPs use channels to allow devices to connect wirelessly without their transmissions interfering with one other.
      - Wired (Ethernet)
        
        advantages/disadvantages
        
        disadvantages
        
        Hard to add devices as you have to buy and fit a cable
        
        Users can't instantly move a device from one location to another as there may not be a network connection available
        
        advantages
        
        generally much faster than wireless
        
        more difficult for unauthorised user to intercept
        
        much less likely to suffer from interference
  - - - A device external to the main computer system
    - - allow for connection to devices outside of the CPU
- - - - Covers a small geographical area
      - Hardware is owned by the individual/ organization that owns the network.
      - Usually connected via UTP, fiber optic or WIFI
    - - Security and back-ups are centrally managed
      - Uses a central server with many attached clients/devices
        
        Client
        
        a less powerful computer that asks for reasources
        
        Server
        
        powerful computer
      - One computer/server reviews requests from clients
    - - Over a geographical wide area
      - Hardware is leased from the telecommunication companies that manage it
      - Connected via fibber optic or copper telephone links or satellites
    - - Every computer
      - Security and Back-ups are a responsivity of the individual
  - - - Domain Name System
        
        Different types of Addresses
        
        IP addresses
        
        Why do we use IP Addresses
        
        There easier to understand for us humans
        Moving the address is easier to update and doesn't affect other users
        
        Types
        
        IPv4
        
        These addresses are limited so we are starting to run out of them for devices. There are almost as many devices as IPv4 addresses
        
        Uses 4 bytes worth of data (255 is the highest number)
        
        IPv6
        
        To deal with the rise in amount of devices IPv6 is used.
        
        IPv6 is made of 8 four digit hexadecimal separated by colons
        
        e.g.00EE:1234:4567:EEEE:4444:4544:5678:ACDE
        
        MAC addresses
        
        Why do we use MAC addresses
        
        so induvidual devices in a network can be found
        
        What is a MAC address
        
        MAC, or Media Access Control, uniquely identifies a device on the network. A MAC address is made up of 48-bit parts.
        
        What are the steps for the DNS (Domain Name Service
        
        The resolver then makes a request with the address
        of the top-level domain for .com
        
        The server then queries a DNS root name server
        
        The URl is received by a DNS resolver solver
        
        Then resolver then makes a request with the address of the top-level domain server for .com
        
        Lastly, the recursive resolver sends a query to the domain's name server
        
        The TlD server then responds with the IP address of the domain's name server
        
        The DNS resolver then responds to the web browser with the IP address for google.com
        
        The IP address google.com (8.8.8.8) us then returned to the resolver from the name server
        
        What is DNS
        
        When we buy a website, we buy the rights to the domain. The name is then added to a domain name server. The DNS has the IP address for the device that holds the domain name. The IP address is returned and the web page loads.
        
        What happens if the DNS doesn't find the address
        
        If it's not found there it goes to the International server
        
        If it's not found there it returns an error
        
        It goes to the national server
    - - A text-based address that points to a specific page on the internet.
      - Example
        
        WWW.ryedale-rlt.co.uk
        
        What is each component in this URL
        
        WWW.
        
        World wide web
        
        ryedale-rlt.
        
        Domain name- the name the company owns that takes you to the website
        
        co.uk
        
        Top Level Domain- where the website is stored
    - - This is a standardized way of transmitting data across a network using HTML
      - When was the WW made
        
        In the late 1980s, Tim Berners-Lee created the WWW