Networks

Created by: jacksie
Created on: 13-11-19 15:21

View mindmap

Factors of networks
- Networks
  - hardware
    - Nic
      - internal bit of hardware
      - usually on motherboard
      - allows device to connect to a network
    - Switch
      - switch transfers data in a network
        Transfers data with the right MAC address
    - Router
      - transfers data between networks
      - important in transferring data in the ineternet
        they transfer units called packets
  - wireless
    - wireless networks uses radio waves
      - they need a WAP, wireless access point
        to connect wirellessly, they need capability
        but you can use a dongle
        dmi dongle used for streaaming
    - WiFi
      - transfers around 2.4 to 5 ghz
        2.4 covers a larger range
        
        5 is quicker
      - the connection is split into a number of channels that overlap
  - peer-peer and client server
    - Clirnt server
      - stores data centrally in the server
      - The client makes a request, processed and executed by server
        server stores users, passwords, data
        some functions need a required password
      - pros and cons
        Central storage, easier to backup
        More secure
        
        however, hard to maintain
        needs IT specialist
    - peer-peer
      - P2P, is more for domestic LAN
      - No centralised management
        Backing up data has to be done individually
        May lead to multiple copies that aren't needed
      - doesn't rely on a server
        will run if a node fails
  - Topolgies
    - Star Network
      - A central switch in the middle
        Allows fewer data collisions than a bus
        
        More than one device can run
        
        Needs IT specialist
        
        in a wireless network, easy to add a node
        
        hardware may be expensive
        
        however may be expensive with an office with 50 terminals
        
        if switch or server crashes whole network fails
    - Ring and bus
      - problem of data collisions and the fact that only one device can transfer
    - Mesh
      - Ideal
        if a node fails, since there are other routes
        however, would cost a lot in a wired network
        becoming more wireless
  - Network Protocols
    - protocols are a set of rules of how to communicate
    - MAC
      - A mac is a 64 bit or 128 bit binary num,ber
        Created by the manufacturer
        they are the unique identifier
        
        permanent
        
        translated into hexadecimal
    - Ip adresses
      - communicate between networks
        IP/TCIP, are used over the internet
        there are two types: static and dynamic
        static IP
        they are permanent, meaning they don't change
        
        Big companies pay a lot for static ip
        This is because they don't wanthe Ip adress to change
        
        dynamic IP
        THis is changes
        used by ISPs
        internet service providers
        
        more cost effective
        
        either a 32 bit or 128 bit binary number
        32 bit is translated into four denary numkbers
        
        128 bit is 8 hexadecimal numbers numbers
        
        Packets
        when data is transferred it is plit into packets
        packets have 3 componenets
        header
        this contains the destination, this is like an envelope
        
        payload
        this is the contents of the packet
        liek the inside of a letter
        
        checsum
        this is a number at the end to check data is not corrupted
        
        Packet switching
        when transferring data
        data is split into packets
        a router reads the packet header and decides the way it travels depending on IP rules
        If a router recives to many packets it may priotise some
        Some packets may be lost, so it checks periodically all packets are there, if so a timeout message is sent
        the packets may not be order so they are arranged
        If the checksum is coorect, a reciept confirmation is sent
    - IP/TCP
      - TCP, is in charge of splitting data into packets
        Other protocols build upon IP/TCp
        HTTP
        hyper text transefr protocol
        transfer data from browser to web server
        
        HTTps
        encrypts all data
        
        FTP
        used to transfer files between devices on a network
        
        POP3
        Post office protocol
        retrieves email from a server
        deltes from the server once you download it
        
        IMAP
        intternet message aaccess protocol
        retrieves email
        deletes email when u delete
        web based clients
        
        SMTP
        used to send mails , and transfer emails between servers
      - Layers
        A layer is a group of protocols with A SIMILAR FUNCTION
        Layers are self-contained- they don@t know whats happening with other layers
        Layers servethe layer above them
        
        Layer 4- application
        This layer sets up data as websites and other applications
        https, smtp
        
        Layer 3- transfer
        this is in charge of data flow, splitting data into packets
        TCP
        
        Layer 2- Network
        connections between networks, directing packets. Used by routers
        IP
        
        Layer 1--link layer
        This converts data into the lectrical signals, transfer data into a physical network
        Ethernet
  - Internet
    - INternet is a netwrok of networks
      - WWW is a collection of hosted web pages on a server
        URL are adresses for a specific webpage or file
        DNS(Domain name server- converts ip adress into a domain name
    - Hosting is when a business stores files of another
      - the most common use is the @cloud'
        third party commpany
        Don't need to pay for hardware
        Don't need to pay an IT staff to manage data
        automated backups
        
        easy to increase your storage
        however, subject to an attack
        another company has access to your fild
        subscription to cloud software may be expensive
    - Virtual networks
      - this is networks made on software
        created by partitioning some bandwidth of a physical network
      - several virtual networks can exist on a physical network
        more cost efficient
        Each network has is its own security and fire wall
        can have access to some of the physical network but not the virtual network
      - VPN
        virtual private network
        this encrypts data making it secure
        used over WANs
        
        school intanet
      - virtual LAN
        breaks up a LAN into several networks on the same hardware
  - SEcurity
    - Passive attacks
      - they monitor quietly data being transferred and pick up sensitive software
        they use software like packet sniffers
      - best defnse is encryption
    - active attack
      - they actively attack with malware
        best defense is firewall
    - Insider attack
      - steals information within a network
    - Brute force attack
      - creates hundreds of likely passwords until it gets it right
        automated software
      - create a lockout after a certain number of attempts
    - Denial of serive
      - floods a network with data
    - Malware
      - delete or modify files
      - scareware
        says its infected with viruses
      - ransomware
        locks files
      - monitoring data and sends it to the hscker
        Untitled
      - viruses
        linked to file .exe
        spread when file is saved
        
        activated when file is open
        
        trojans
        data seems legitimate but isnt
        
        worms
        self replicate without user help
      - open backdoors for future attacks
- bandwidth
  - the amount of data that can be transferred
    - mbps
      - the better the bandwidth the greater the performance
- for wired networks
  - the hardware
    - Fibre optic cables are faster than copper wires
- The topology
  - peer-peer faster than client server
- bandwidth availability
  - heavy traffic and congestion slows down networks

Get Revising

Networks

Comments

Similar Computing resources: