computer science 1.3.2.

computer science 1.3.2.

1. A local area network (LAN)

2. A local area network (LAN)

   • consists of a series of computers linked together to form a network in a circumscribed location.
     • example :networks employed by small businesses, small organisations, schools, colleges, universities and in homes.
   • A wide area network (WAN)
     • is a network that is spread over a wide geographical area. It can cover more than one site, or be spread across a country, or even the world. The WAN allows the head office to communicate and share data with the sub-offices and branches. Communication is done through national telephone infrastructures or via wireless transmission.
       • example Organisations that have more than one office or branch, such as banks, tend to use a WAN

3. Factors that affect the performance of networks

   • the number of devices on the network. the bandwidth of the transmission medium. the type of network traffic. network latency. the number of transmission errors.

4. Client-server and peer-to-peer networks

   • This type of network separates computers into one of two classifications - servers and clients.A server is a computer that manages and stores files, or one that provides services to other computers on the network
     • examples file servers - hold and maintain user files applications servers - allow programs to be run over a network web servers - hold and share web pages print servers - manage printing across a network mail servers - handle emails between users
   • in a peer-to-peer (P2P) network, all computers have equal status - no computer has control over the network. There are no servers or clients.
     • examples P2P networks are best suited to smaller organisations that have fewer computers, or where fewer computers need access to the same data.web servers - hold and share web pages print servers - manage printing across a network

5. lan

   • wireless access point
     • a device that creates a wireless local area network, or WLAN, usually in an office or large building. An access point connects to a wired router, switch,
   • Routers
     • A router can form a LAN by connecting devices within a building. It also makes it possible to connect different networks together.
     • Switches
       • A switch performs a similar role to a hub and a bridge but is more powerful. It stores the MAC addresses of devices on a network and filters data packets to see which devices have asked for them
         • Network interface card (NIC)
           • Network interface card (NIC)
             • NICs enable desktop and laptop computers to connect to a network.
               • NICs are small circuit boards that connect to the motherboard
   • transmission media carry data signals from one computer to another. Media are either wired or wireless.

6. DNS

   • DNS, or the Domain Name System, translates human readable domain names (
     • for example, www.amazon.com) to machine readable IP addresses (for example, 192.0.2.44).

7. Hosting

   • Hosting is the storing of files and data on a web server. The web server is referred to as a host.
     • EXAMPLE The URL (uniform resource locator) for a website includes the host name. For example, the host name bbc.co.uk is included in the URL www.bbc.co.uk..com .uk .net .gov .edu

8. The cloud

   • The cloud is a generic term for remotely accessed storage. This storage is accessed through the internet.
   • several advantages:
     • educed need to make backups the ability to access files,

9. Star networks

   • Any device connected to a network is referred to as a node
   • In a star topology all nodes indirectly connect to each other through one or more switches
   • Advantages and disadvantages of using a star topology
     • ach node is separately connected, therefore a failure of one node or its link, (transmission media), does not affect any other nodes
       • the whole network fails if the switch fails as no node can communicate
   • mesh tec
     • network which each node is connected to all the other node
     • Advantages and disadvantages of using a mesh topology
       • messages can be received more quickly if the route to the intended recipient is short
         • messages can be received more quickly if the route to the intended recipient is short