Networks

Networks

1. Networks

   • Is a set of connected computers and other devices in order to share resources
   • Advantages
     • Workgroups - Groups of users can easily send data to each other over networks
     • Shared databases - Allows different users to make and modify databases
     • Distributed systems - Possible to divide a problem into separate parts for other computers to solve, so the task can be done faster
     • Communications - Skype, email - better than letters and conferences
     • Device sharing - Jobs can be sent to devices (eg printers) from any computer
     • Software sharing and maintenance - Can update software on all computers at the same time
   • Disadvantages
     • Expertise - Building a server needs knowledge
     • Security - Can help unauthorised people get access to data

2. Network hardware

   • Network Interface Card (NIC) - Circuit that prepares and generates
   • Terminator - A device attached to the end of a bus network to prevent signals from bouncing
   • Repeaters - The signal weakens and the information it carries can be corrupted. A repeater cleans a message and sends it to the next segment of the network
   • Hubs - They are repeaters, but with more than one output port. They can boost signals and send it to all devices in the output ports
   • Bridges - They connect different network segments as well as different media. They can operate on packets and send them to the right segment. They speed up a networks performances
   • Switches - It is a high-speed bridge, it has a dedicated CPU designed to perform switching operations
   • Router - They work with data packets, a router allows data to be sent between departments or ISP's
   • Wireless access points - allows a WiFi device to connect to a wired network

3. Types of Networks

   • Peer-To-Peer
     • All computers are equal.
     • Security is up to each user
     • Often uses a hub
     • Difficult to keep track of who has what information
     • Suitable for a small office or home
   • Client Server
     • Most common network
     • Needs one computer dedicated as a server
   • Star topology
   • Ring topology
   • Bus topology

4. LAN vs WAN

   • LAN - Local area network. Located in one site. Short range.
   • WAN - Wide area network. LANs connecting to other LANs. Can be used to connect a companies LANs together even if they are in other countries

5. Terms

   • IP address - a unique string of numbers separated by full stops that identifies each computer
   • MAC address - A MAC address is given to a network adapter when it is manufactured. It is hardwired or hard-coded onto your computer's network interface card (NIC) and is unique to it
   • Packet - is a unit of data made into a single package that travels along a given network path
   • Protocols - rules used for devices to communicate

6. Security

   • People dont want data to fall into the wrong hands
   • Strong passwords are needed so they are hard to guess
   • Packets of data are encrypted so if they do fall into the wrong hands they cant be used
   • Levels of access are determined by user id - they stop unauthorised people from messing with the network

7. Network policies

   • Disasters - they happen - companies have procedures and plans with three steps - prevention, detection and correction
   • Failover - Automatic switching to a backup computer system in the event of system failure
   • Back-up - Data is copied regularly to a storage device in case some is deleted
   • Archiving - When data is no longer is used it is stored somewhere else but deleted from the primary system in case someone needs the data again

Images and files in the map