Unit 4 Network.pdf

YEAR 10 UNIT 4 - NETWORKS & EFFECTS 4.1 NETWORKS COMPUTER NETWORK - Consist of 2 or more devices linked together to share data - Network can vary in size -...

YEAR 10 UNIT 4 - NETWORKS & EFFECTS 4.1 NETWORKS COMPUTER NETWORK - Consist of 2 or more devices linked together to share data - Network can vary in size - Computers not connected to a network are known as “stand-alone” computer ADDRESS INTERNET PROTOCOL (IP) ADDRESS - Each device on the internet is given a unique address - Assigned to computer by internet service provider (ISP) - Define the rules that must be agreed by senders and receivers of data communicating through the internet ★ Identifies location of a device on a network - Changes each at login at different location - IP address version: ➔ IPv4 - 32 bits, 4 groups of 8 bits ➔ IPv6 - 128 bits, 8 groups of hex digit MEDIA ACCESS CONTROL (MAC) ADDRESS - Physical address, never change - Based on NIC (if NIC change, MAC also changes) - 48 bits - six groups ★ Number which uniquely identifies device when connected to network - Data packet sent through switches have MAC address - Identifies source of data and MAC address which device will receive it NETWORK DEVICES NETWORK INTERFACE CARD (NIC) - Allow device to connect to network - Turns binary data into electrical signals allowing access to network (DAC) - Each NIC given a unique hard-coded MAC address at manufacturing stage - When installed NIC in device, it uniquely identifies the device - WNIC - use wireless conductivity - Acts as the connection point for a network cable or wireless signal DATA PACKETS - Data is moved around networks in the form of data packet - Split up into numbers of packets when sending data - Each packet is transmitted separately - Packets of data have header containing: ➔ Sender’s & Receiver’s IP address ➔ sequence/identity number of packets ➔ Packet size ➔ Data packets making up the whole message  YEAR 10 UNIT 4 - NETWORKS & EFFECTS HUB - Hardware device that have numbers of other devices connected to it - Hubs take data packet received and send it to all connected devices on the network - Used to connect devices together to form a LAN - Not secure - every device connected receives data - Slow bandwidth, unnecessary traffic in network SWITCHES - “Intelligent” version of hub - Only send data to specific device - Connect number of devices together to form a LAN - Switch stores MAC address of all devices connected - Uses look up table to match MAC address and directs it to correct device - More secure than dubs - Faster bandwidth, network traffic reduced SIMILARITY DIFFERENCES - Both used to connect devices to form a - Hubs sends data to every device LAN (Local area network - smaller - Switches sends to specific device network) - Security lower with hubs than switches - Both use data packets - Switch use look-up table to determine destination - Switch use MAC address to locate destination BRIDGES - Used to connect LANs together - Devices that connect one LAN to another LAN that uses the same protocol (communication rules) - Connects different parts of a LAN so they can act as single LAN, allowing communication with each other - Unlike routers, bridges cannot communicate with other external networks, such as the internet ROUTER - Used to route data packets from one network to another network, based on IP address - Each router has its own IP address - Used to join a LAN to the internet - Through wireless / cables - cables have more stable connections - Router read and decide where to send it, decides the fastest route, format data suitable for the network  YEAR 10 UNIT 4 - NETWORKS & EFFECTS ROUTER TRANSMISSION OF DATA PACKET - Router receives data packet at one of its port, it checks the destination of IP address against the stored routing table (stored in router’s RAM) - Determines whether the data packet is for its own network or for another - Data packet will be transmitted to a different router (external network) until IP address matches - Then data is routed to the local switch / hub - Allows router to determine packet’s next path - Data packet will pass through a number of routers before reaches its final destination ROUTER BRIDGES - Connect various type of network together - Connect LANs together - Scans device’s IP address - Scans device’s MAC address - Sent out data using data packets - Sent out data using data packets - Connected networks will use different - Connected networks will use the same protocols protocols - Routing table used to direct data - Does not use routing table - Has more than 2 ports - Only has 2 ports WI-FI & BLUETOOTH - Offer wireless communication between devices - Use electromagnetic radiation as carrier of data transmission BLUETOOTH - All centred on frequency of 2.45 GHz - Do not interfere with other devices as each communicating pair uses different channel - Spread-spectrum frequency hopping - devices constantly change channels used, to minimise the risk of interference with other devices - Useful when speed of data transmission is not critical - for low-bandwidth applications - Uses key encryption to create secure WPAN - Devices have to be close together WI-FI - Each band is further split into channels - The higher the GHz, the faster the data transfer rate but the shorter signal range - Best suited to operating full-scale network as it offers much faster data transfer rates, better range and security than bluetooth - Allow device to access internet wirelessly at any access point / hotspot to 100 metres away  YEAR 10 UNIT 4 - NETWORKS & EFFECTS SIMILARITY DIFFERENCES - Wireless - Wifi has higher bandwidth than BT - Use radio waves - Wifi has higher range than BT - Creates local connection - Wifi has higher cost than BT - Similar frequency of signal - Wifi is more complex to use than BT - Bluetooth is less secure CLOUD COMPUTING (STORAGE) - Method of data storage - data is stored on remote server - Data redundancy - same data stored on more than one server ➔ PUBLIC - client and cloud storage providers are different companies ➔ PRIVATE - client & cloud storage provider are in the same companies (operate as single entity) ➔ HYBRID - combination of both public & private ; some data resides in the privates cloud and less-sensitive data can be accessed from a public cloud storage provider ADVANTAGES DISADVANTAGES - Accessed anytime, anywhere as long as - Security risk internet connection is available - Cost can be high if large storage - No need to carry an external storage capacity is required device - Cannot access with slow and unstable - Remote backup of data - in the event of internet connection data loss - Potential failure of cloud storage ; risk - Allow recovery of data of loss of all data - Offers almost unlimited storage capacity (at a price) NETWORK ENVIRONMENTS INTERNET - international network - global network for everyone INTRANET - internal restricted access network - private network for specific organisation EXTRANET - secure extension of intranet for external collaboration  YEAR 10 UNIT 4 - NETWORKS & EFFECTS NETWORK TYPES LOCAL AREA NETWORK (LAN) - Network that connects devices within a small area, such as home, school, office - Consist number of computers and devices which will be connected to hubs/switches - Used for short-distances communication, may involve wired connection within a single building ADVANTAGES DISADVANTAGES - Allow sharing of resources such as hardware - Easier spread of viruses throughout the whole and software network - Easy communication between users of LAN - - Queues for shared resources (printer) using simple text messaging - Slower access to external networks - Use network administrator that ensures - Increased security risk compared to security - maintains passwords stand-alone comps - Use of LAN is constantly monitored - monitor - If main server breaks down → networks no data traffic within network longer functions properly WIRELESS LOCAL AREA NETWORK (WLAN) - Similar to LANs, but without wires / cables - Provide wireless network communications over fairly short distances using radio / infrared signals Access Point (APs): - Connected to wired networks at a fixed location - Used to extend wireless network coverage - Used spread-spectrum technology (30-50m) or infrared (1-2m, easily blocked) - Receives and transmits data between WLAN and wired network - End-users access WLAN through WLAN adapters which are built into their devices WLAN - WIRELESS LAN - WIRED Easier to expand network - no need to connect devices Cables provide more reliable & stable network as wireless using cables; Increases mobility for devices - provided connectivity are often interfered they are within range of AP No cables - safety improvement & flexibility A lot of wires is hazardous - tripping, overheating, fire, disconnection during cleaning Increased chance of interference from external sources Cheaper overall Data is less secure - easier to intercept radio waves Immobile - have to be closer together for cable Essential to protect data transmission using encryption connections Data transmission rate is slower Faster data transfer rate Signals may be stopped by thick walls No ‘dead spots’ - all connected by cables Areas may have different signal strength - ‘drop out’  YEAR 10 UNIT 4 - NETWORKS & EFFECTS WIDE AREA NETWORK (WAN) - WANs connect computers or networks that are FAR apart geographically - Can be formed by connecting multiple LANs using a router - WANs use public communication networks like network lines and satellites - Also use dedicated or leased communication lines - cheaper and more secure (lower risk) ★ WAN - 100km to 1000km ★ MAN - 1km to 1000km - metropolitan area network (LARGE CITY) ★ LAN - 10m to 1000m  YEAR 10 UNIT 4 - NETWORKS & EFFECTS 4.2 NETWORKS ISSUES & COMMUNICATIONS Security issues regarding data transfer: - Hacking - Phishing - Pharming - Viruses AUTHENTICATION METHODS PASSWORDS - Accessing email account - Carrying out online banking - Accessing social networking sites Ensure Password Protection - Run anti-spyware software to ensure that your password isn't stolen - Change password on a regular basis in case it as been cracked / accidentally release - Always use strong password containing: ➔ upper and lower case ➔ numerical value ➔ other keyword characters ➔ at least 8 characters ZERO LOGIN / BIOMETRICS - Login without password - Relies on smart technology to recognise user with biometrics and behavioural patterns - Builds a complex user profile based on biometrics / unique behaviour eliminating the need to key passwords - Biometrics - fingerprint, face recognition - Unique behaviour - how user normally uses device and swipe screen MAGNETIC STRIPE READER - Part of security system, the stripe on the back contains data such as name, ID, sex, date of birth - Swipe through magnetic stripe card reader to read data and identify user - Often have holographic image (hologram) embossed on the card - makes forgery difficult Advantages Disadvantages - Easy system to use - Less secure than biometrics - easy to - Not expensive to implement copy - Cards can be remotely deactivated if - Card wears out with use lost / stolen - If card reader head is contaminated, card cannot be read  YEAR 10 UNIT 4 - NETWORKS & EFFECTS SMART CARDS - Adding a microchip & antenna to a magnetic stripe card → smart contactless card - Device reads card from a distance of a few centimetres (NFC) - User may be invited to enter PIN to see if it matches to the one stored on the microchip PHYSICAL TOKEN - Type of hardware security device - form of authentication to prove user has possession of token - Solid object used by banks for remote account access - Contains internal clock that randomly generates an 8-digit number, changes every few minutes - Card inserted, user enters PIN and device generates a one-time password (OTP) - OTP must be entered on bank’s webpage for user to access their account CONNECTED physical token DISCONNECTED physical token - Device transmit OTP directly to computer - User has to key in OTP manually using USB port - No need manually enter data ELECTRONIC TOKEN - Software tokens, installed in user’s computer as an app - User opens the app which generates an OTP which is valid for a limited amount of time - User enters this OTP into the website and together with other forms of authentication such as fingerprint or face recognition → verified → access - The website server runs on the same software as the app - Both user and website use synchronised clocks thus generating the same OTP ANTI-MALWARE SOFTWARE MALWARE - A malicious software designed to harm computer and mobile devices - Steal personal information - Disrupt normal computer operations - Gain unauthorised access - Extort money by locking files VIRUSES A program which spreads & replicates; intention to delete, corrupt or alter files/data to prevent normal running of a computer SPYWARE Secretly monitors and gathers information about users TROJANS Pretends to be a legitimate software but harms users computer  YEAR 10 UNIT 4 - NETWORKS & EFFECTS ANTI-VIRUS SOFTWARE - A type of anti-malware software - Protects devices against potential virus attack - allow to run in the background Common Features: 1. All software and files are checked before they are run/loaded 2. Compares possible virus against database of known viruses 3. Carry out heuristic checking - check for behaviours that may indicate a possible virus 4. Any possible files/programs infected are place into quarantine - Allows virus to be automatically deleted - Allows user to make decision of deletion - User may know that the file is not infected - false positive 5. Kept up to date - new viruses constantly discovered 6. Full system check every once a week - some viruses can only be identified by full system scan ELECTRONIC CONFERENCING - 3 types of conferencing - video, audio, web VIDEO Conferencing - Uses video & sound - Uses: webcam, monitor, microphone, speaker - Substitute for face-to-face conferencing Advantages Disadvantages - Easier to access documents - Time lag in responses (delays) - No travelling - Images can jerk - poor internet - Reduce travelling cost - Expensive to set up - Better for environment - less pollution - Time zone difference - Relies on good network connection AUDIO Conferencing - Uses audio (sound) - Known as phone conference - done over telephone network - Possible to hold audio conference using computer - only requires speaker and microphone WEB Conferencing - Uses internet to permit conferencing - Focuses on interaction and collaboration - document sharing, presentation, share screen, etc - Requires computer with high-speed, stable internet connection - Meeting controlled by organiser