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