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Summary IT A-Level, Covers all of topic 14 communications technologies
- Course
- ICT
- Institution
- 12th Grade
IT A-Level, Covers all of topic 14 communications technologies, Mostly for Cambridge students
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14 Communications Technology14.1 Networks
network: Two or more computers or devices connected together so they can communicate and
share data and resources.
Local Area Network (LAN):
A LAN is a network that is limited to a small geographic area, such as a single building, a
campus or a group of closely located buildings.
It has high data transfer speeds of upto 1 GB per second.
Data transmission errors are fewer because data is transferred over a short distance
Normally connected using copper wire, fibre optics cables or radio waves.
It can be kept more secure as a smaller number of devices need securing. The security is
also the responsibility of network owners.
There is usually private ownership as they are often owned, setup and maintained by
single organization or individual such as a business, school or government institution.
The organization has control over the LANs configuration and security.
Advantages:
Enables efficient sharing of files, printers and applications
Reduces costs by minimizing duplicate equipment
Has high data transfer rates which allows fast communication and data exchange
It has high scalability to accommodate the addition of new devices and network growth
Facilitates centralized data storage and management on servers for better organization
and security
Disadvantages:
Initial installation and setup can be expensive
, Has a limited physical range / confined to smaller geographical area
It relies on centralized hardware like servers and switches, making it prone to fail if the
central components fail
Easier to spread virus/more susceptible to security threats
Wide Area Network (WAN):
A WAN is a type of computer network that spans a large geographical area, connecting
multiple LANS and other network devices.
It can be within a country or can spread across several countries.
Internet is the largest WAN
It is often restricted to lower transfer speeds normally less than 200 mb.
It has greater chance of errors occurring as data is transferred over longer distance.
Connections could include physical connections such as copper wire,etc and others like
radio waves, microwaves, transmission towers and satellites.
It is more susceptible to security issues as a large number of devices need securing. The
organization will normally need to rely on the security measures of others for part of the
network, so they will not be able to control security in these areas.
Elements of the network are often owned by a third party, so they have to rely on the
control and maintenance of others.
Advantages:
It enables global connectivity and makes communication and resource sharing even
easier.
It is cost efficient since resources can be virtually shared
Has high scalability, WAN can seamlessly grow with organizational expansion
Enables remote access
Disadvantages:
It has low latency, as data is transmitted over long distances
Building and maintaining a WAN is expensive as a large geographical coverage needs to
be covered and maintained.
, WANS are alot more complex to design, implement and manage compared to LANs as
they require specialized knowledge and expertise.
There is very limited control in WANS as a large number of devices/users need to be
monitored and controlled and a lot of service is dependent on third parties/providers
Due to a larger network setup, there is a higher risk of unauthorized access and
breaches
Client-Server:
A client server network is the one that contains two types of computers, a client and a
server.
The server(s) in a client- server network are a central point of control and provide a
dedicated function for the network.
All other computers in the network are all connected to the server to allow it to perform
its dedicated function.
Most client server networks operate using a request response method.
A typical operation in this method is a client sends a request to a server to ask the server
to perform a task and the server responds by performing the task.
Server Type Function
File Server Stores and manages data files. This saves the need for extensive storage
space on client computers. They allow a user to use any client computer in
the network and still be able to access their files and also any publicly
shared files available. They also allow a central backup of all data to be
made.
Web Server Stores, processes and transmits web pages.
Mail Server Sends and receives emails. It stores incoming emails for the user that can
be downloaded when requested. It forwards outgoing messages to the
correct destination. Most mail servers have security checking software
that will scan emails for issues such as known viruses and malware. They
can also be set to check for inappropriate content and spam.
Application Server Installs and runs software applications. They provide a platform to run
both desktop and web applications.
Print Server Receives print jobs from client computers and sends them to the correct
printer. This allows many client computers in a network to use the range
of printers available. They can be set to print to a specific printer. They
can also be set to find the next available printer or the closest printer to
the client. If many jobs are sent to the print server at a time, it will queue
the jobs until it can deliver them to a printer.
, FTP Server Manages the transfer of data that uses the file transfer protocol (FTP). It
keeps a log of all activity involving FTP. Uses a lot in the transfer of files
over the internet.
Proxy Server Acts as an intermediary between clients and other servers by receiving
client requests and forwarding them on to the relevant server. It provides
an added level of security in a network, protecting clients directly
accessing resources on another server. For this reason, it can also be set
to act as a firewall.
Virtual Server Shares the hardware of another server. Created using virtualization
software on another server. Multiple virtual servers could be created on
one physical server. A virtual server can be given the capabilities of any of
the above physical servers. Businesses sometimes use third party
virtual servers that will act as a web server, for the business to host its
website. This allows the hosting company the ability to host several
businesses websites on the hardware of a single physical server.
Advantages:
Files can all be located in a single place and backed up on a regular basis. This means
each user doesn’t need to be responsible for this.
Security for the network can be controlled from a central point, meaning each user
doesn’t need to be responsible for this.
Levels of access can be applied o resources and data on servers, so only those that
should have access will do so. This is very beneficial when some data ad resources have
to be kept confidential.
Updates for any software or network peripherals can be rolled out from a central
location. Therefore, the business is not reliant on each user installing updates
Disadvantages:
Can be very expensive to set up due to the need to buy expensive equipment, such as
servers.
Expensive to maintain as specialist knowledge is required to setup and maintain the
servers.
Failure of a server will mean that functionality is unavailable for all users. For example;
no user can access their files if a file server fails.
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