A router is a device that forwards packets from network type to another. The backbone of the Internet is made up of multiple networks of different types and therefore routers are used to forward the packets to their destination.
A gateway is a node in a LAN through which data is passed to the Internet. It is usually a router.
Servers are specific purpose computers design to provide services to other devices on the network (or to handle requests from other networks). There are lots of different types of server and one computer can provide multiple server services.
Examples of Servers Include:
This server stores user’s files and folders so that they can be accessed from any device on the network. Can also be used to perform backup functions if a separate back-up is not used.
A web server performs the function a web host, providing web page access to other clients across the internet. When you load up a page from the internet the web pages, images, etc that are display on your web browser are provided by a web server.
A proxy server is a server that acts as a middle man, forwarding packets from one computer to another. A proxy server can provide anonymity for web users(the originator’s IP address is replaced with the proxy server’s IP. They can also provide Internet filter for businesses and schools because only packets from authorised websites (known as white-listed sites) will be forwarded.
**Not specifically mentioned on the 9608 specification **
An authentication server is a server to that hols username, password and user access level (UAL) information. When you log on to a network the authentication server decides whether to autorise your logon request.
**Not on the 9608 syllabus but very useful to know **
Switches are devices within a network that forward packets within the network itself. They allow multiple computers to connect to a network through a single node and therefore reduce the wiring requirement. This is especially important in larger networks.
Switches operate at the Data Link Layer and forward data using MAC addresses, rather than IP addresses.
Network Interface Card
Devices that connect to a network require a network interface controller to do so. These can be wired or wireless.
Wireless NIC (Wifi / Bluetooth)
Larger networks are often broken down into smaller networks for performance reasons. Each of these network segments are connected together through the use of a network bridge.
If a LAN spans a long distance ( > 100m ) then transmitting the data along an ethernet cable will result in significant interference and therefore a reduction in network throughput. In order to deal with this issue network repeaters are used to boost the incoming signal before sending it on to the next ethernet cable.