Networks

LAN

A LAN is useful for sharing resources like files, printers, games or other applications. A LAN in turn often connects to other LANs, and to the Internet. Local area networks are supplies networking capability to a group of computers in close proximity to each other such as in an office building, a school, or a home.

 

Advantages

• They are faster than wireless networks
• many computers in the same LAN have access to the same files, folders and peripherals like printers
• they are cheaper

Disadvantages

•  Special security measures are needed to stop users from using programs and data that they should not have access to;  
• Networks are difficult to set up and need to be maintained by skilled technicians.  
• 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

An adapter circuit board installed in a computer to provide a physical connection to a network.

 

Hub

In computer networking, a hub is a small, simple, inexpensive device that joins multiple computers together. Many network hubs available today support the Ethernet standard. Other types including USB hubs also exist, but Ethernet is the type traditionally used in home networking.

 

Router

A network device that forwards packets from one network to another. Based on internal routing tables, routers read each incoming packet and decide how to forward it. The destination address in the packets determines which line (interface) outgoing packets are directed to.

 

Switch

A network switch (sometimes known as a switching hub) is a computer networking device that is used to connect devices together on a computer network by performing a form of packet switching. A switch is considered more advanced than a hub because a switch will only send a message to the device that needs or requests it, rather than broadcasting the same message out of each of its ports.

Wireless access point

In computer networking, a wireless Access Point (AP) is a device that allows wireless devices to connect to a wired network using Wi-Fi, or related standards. The AP usually connects to a router (via a wired network) as a standalone device, but it can also be an integral component of the router itself.

Protocols

When data is exchanged through a computer network, the rules system which the computer follows is called a network protocol.

Topology

There are three main 

Bus topology:

the advantages of a bus topology are that there is one common linking cable,nodes connected off the cable and it is cheap

slows down with heavy traffic

lots of data collisions

breakage to cable affects whole network

limited distance possible

Star topology:

shared link to servers

most common

few data collisions

fast

can set up independent segments

Ring topology:

one common liknking cable

passes all nodes

one direction traffic

fast performance

Homework- 10/03/15

When a user types a certain website's domain name such as http://www.neatorama.com into their browser the DNS server translates this address into an IP address such as "23.239.6.122" in this instance. This IP adress is used to locate the server of that websit and give you access to it.

Within the DNS server there is a table of domain names that are linked to IP addresses. There are a lot of DNS servers for the internet so if your local DNS server does not have the domain name you want to access listed, the request can be forwarded to more servers.

The advantage of DNS servers is that you do not need to remember a long number to go to each website but only an address. However, disadvantages are that it is a centralized server that you have to connect to every time you access a new website. This also means that the breakdown of key DNS servers could seriously harm the world wide web. Finally, a common form of computer hacking is done by DNS spoofing, meaning you are sent to the wrong IP address and therefore website that could be malicious or harmful.