Computing Revision Cycle test 18th jan

Networks

Lan (Local area Network) Computers are connected together over a small geographical area such as a single building or a single sight.

Examples of LANS are House networks and School networks.

Wan (Wide area network) computers are connected over a large geographical area. This could be several sites town, wide, country wide or international. The biggest WAN would be a global connection of networks such as the internet.

Factors Effecting Networks

Network latency , Number of users, Network capacity.

Client server is a network that relies on a central server. All client devices request service from the server. Additional power may be needed such as high end powerful servers.

Peer to peer networks all computers have equal status each device can act as a client and a server all devices can request and provide network services. No additional hardware or network is needed to set it up.

The security used on these networks are antivirus and firewall.

Advantages of computer networks.

It makes file sharing easier.

It increases cost efficiency

It is flexible

It boost storage capacity

Disadvantages of computer networks

It allows more computer viruses and malware

It is expensive to setup

It posses security difficulties

It requires a professional to handle it

DNS

DNS stands for Domain name service

When you type in a URL into the web browser the computer will query a DNS server.

The DNS server has a list of all domain names and there associated IP addresses

Without the DNS server the user would have to type in a IP address to access the webpage.

Star and mesh topology

In star topology all of the devices connect to a central device usually a router or a switch.

In mesh topology devices are connected to lots of other devices with no central switch.

The pros of a star network is that it needs fewer cables it is easier to add or remove devices it is simple to understand and troubleshoot but the cons of it are that if the central switch fails then the entire network fails.

The pros of mesh topology is that it allows packets to be routed around bottlenecks and a single failure wont stop the rest of the network but the cons is that it needs more cables and also it is harder to trouble shoot and understand and it is hard to remove or add devices