Networks

LAN (Local Area Network)

Advantages:

• You can share peripheral devices like printers. This is cheaper than buying a printer for every node.
• You can save your work centrally on the network’s file server. This means that you can retrieve your work from any node on the network.
• Users can communicate with each other and transfer data between nodes very easily. 
• Distributed processing
• When there is an update it only has to be loaded onto the file server rather than every computer.

Disadvantages

• Special security measures are needed to stop users from using programs and data that they should not have access to.
• They can be difficult to set up and need to be maintained.
• If the file server develops a serious fault, all the users are affected, rather than just one user in the case of a stand-alone machine.

Hardware

NIC: This is a network interface controller, is a computer hardware component that connects a computer to a computer network (LAN).

Ethernet Hub: A device for connecting multiple Ethernet devices together and making them act as a single network.

Router: The piece of network hardware that allows communication between your local home network - i.e. your personal computers and other connected devices - and the Internet.

Switch:  A network switch is a small hardware device that joins multiple computers together within one local area network (LAN).

Wireless Access Point: A device that allows people to connect devices on a wireless LAN to a wire-based network.

Topology

"Ring- A network topology that is set up in a circular fashion in which data travels around the ring in one direction and each device on the right acts as a repeater to keep the signal strong as it travels. Each device incorporates a receiver for the incoming signal and a transmitter to send the data on to the next device in the ring. The network is dependent on the ability of the signal to travel around the ring.
 

Star-In local area networks with a star topology, each network host (for example a PC) is connected to a central hub with a point-to-point connection. All traffic on the network passes through the central hub. The hub acts as a signal booster or repeater. The star topology is considered the easiest topology to design and implement. An advantage of the star topology is the simplicity of adding additional nodes. The primary disadvantage of the star topology is that it may need a lot more cables, and if the hub breaks everything will stop working.
 

Bus-In local area networks where bus topology is used, each machine is connected to a single cable. Each computer or server is connected to the single bus cable through some kind of connector. A terminator is required at each end of the bus cable to prevent the signal from bouncing back and forth on the bus cable. A signal from the source travels in both directions to all machines connected on the bus cable until it finds the MAC address or IP address on the network that is the intended recipient. If the machine address does not match the intended address for the data, the machine ignores the data. Alternatively, if the data does match the machine address, the data is accepted. Since the bus topology consists of only one wire, it is cheap to implement compared to other topologies. However, there is a higher cost of managing the network. Additionally, since only one cable is used, if the network cable breaks the whole network will be shutdown."

simple.wikipedia.org/wiki/Network_topology

Types of Network

 

Homework 10/3/15: DNS

DNS (the domain name system) is the TCP/IP protocol (rule) used to translate domain names, like the example one, into binary IP addresses that the browser can use. Servers called DNS servers are used to do the converting as they have a database of IP addresses, when you request a URL it looks it up and returns the IP address or searches for it on other DNS servers. The advantages are people don't need to remember IP addresses as web addresses are much easier to use. It is also easily upgradeable without all web addresses needing to be the same. The disadvantages are DNS spoofing - returning someone to the wrong IP address - could lead to private data being taken. It is also centralised so if it goes down the whole internet does.