Networks

LAN (Local Area Network)

LAN or Local Area Network is most commonly used as Ethernet LAN, Ethernet LAN is used with two or more Nodes (Nodes are devices connected to the network), LAN commonly used for things like: Sharing Files,  Multiplayer Video Games or other tasks.

Advantages

• They are often faster than wireless network connections
• Anyone who wants a file can join the network and access it.

 Disadvantages

• Anyone who can access the network can access everyone who is on the network
• Networks are difficult to maintain and require specialised technicians.
• The ability to expand the network is difficult compared to a wireless networks and Either cables have to be strung underfoot, or walls and floors ripped out and jacks added in to allow users to connect to the network.
  

  DNS servers

  Advantages of a DNS Server:

  An advantage of using DNS to redirect clients is that it is a natural way of informing the clients about the service addresses. It is used by many existing network services, and is very likely to be used by those to come as well.
  Moreover, DNS is supported by a huge infrastructure of millions of DNS servers, capable of caching the answers our redirector generates. Once we make this infrastructure work for us, both efficiency and availability of our redirector considerably increase. 
  One more important advantage of DNS is that it allows multiple replica addresses to be returned, enabling the client to choose one from them.
  Disadvantages of a DNS Server:

  On the other hand, using DNS-based redirection leads to a few difficulties. The first of them is caused by the fact that DNS queries carry no information about the client that triggered the name resolution.
  All that the service-side DNS server knows is the network address of the DNS server that asks about the service location.
  Therefore, we have to assume that clients always use a DNS server that is close to them, and approximate a client's location to that of its DNS server. Whether we consider it to be a drawback or not depends on the accuracy we want to achieve.

  Studies show that 64% of clients are located in the same network as their DNS servers. Thus, as long as we do not need strict per-client redirection, the location of the client DNS server approximates the client well enough.

  How a DNS server accesses a website

  DNS is a protocol within the set of standards for how computers exchange data on the Internet and on many private networks, known as the TCP/IP protocol suite. Its basic job is to turn a user-friendly domain name like "Google.com" into a IP address like 70.42.251.42 that computers use to identify each other on the network.

Hardware

NIC

An NIC or network interface controller, is a component of hardware that connects a computer to a computer network

Hub

A hub or network hub is used to connect multi Ethernet devices making them act as a single network segment.

Router

A Router is a device that forwards Data Packs between computer networks, creating an overlay internetwork.

Switch

A Network hub is a computer networking device that is used to connect devices together on a computer network by performing form of packet switching.

Servers

There are many requests that the server can provide for the client such as: The server component provides a function or service to one or many clients, which initiate requests for such services. For example, a web server serves web pages and a file server serves computer files. A shared resource may be any of the server computer's software and electronic components, from programs and data to processors and storage devices.

What is the Internet?

 The Internet is a massive public spiderweb of connections from different devices. It connects personal computers, mainframes, cell phones, GPS units, music players etc. All of these computer connections exist for the sake of free information sharing. All these devices together create the network of networks. The Internet is a system that changes in little ways as elements join and leave networks around the world. Some of those elements may stay fairly static and make up the backbone of the Internet.

What is WWW?

The World Wide Web is a network of computers that serve webpages. The World Wide Web is a major component of the Internet, along with email, ftp, and some other minor protocols. Documents on the World Wide Web are traditionally written in HTML, a major component of the web. HTML defines the appearance and content of what the website wants to be.

TCP/IP

TCP/IP (Transmission Control Protocol/Internet Protocol) is the basic communication language or protocol of the Internet. It can also be used as a communications protocol in a private network .When you are set up with direct access to the Internet, your computer is provided with a copy of the TCP/IP program just as every other computer that you may send messages to or get information from also has a copy of TCP/IP.

 Network Topology

There are three main Network Topology's and they are:

Bus Network

A Bus Network is a network of computers which has one common linking cable and nodes that are connected of the cable, another reason why this is often used is because it is cheap and easy to setup. Although it is easy to setup and cheap it doesn't work to well if you have high activity between devices as this would cause a lot of data collisions.

Star Network

A Star Network is a network of devices with a central hub system acting as a go between for all of the devices on the network, the advantages of the network work would be that it wouldn't cause many data collisions and would be a fast, reliable network. The main disadvantage and it is a big disadvantage is that if the central hub were to go down that would cause the network to be inoperable and the Network wouldn't be able to function while the central hub was down. Another disadvantage would be that all information travels through the main central hub so if the central hub was compromised that would mean that the whole networks information would be available.

Ring Network

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 ring 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. When a device sends data, it must travel through each device on the ring until it reaches its destination.



 

System Software

The 3 different types of software:

• System Software:

• Operating System
• Device Drivers
• Maintenance

• Developing Software

• Programming Languages
• Utilities

Developing software use Compilers, Compilers translate the high-level code used by the programmer into machine instructions required by the computer. They also use Interpreters, interpreters also translate high-level code but they translate it and execute it one instruction line at a time instead of translating the whole code. Assemblers are also used to translate assembly language but they translate it into Mnemonics instead of binary code, Mnemonics are a type of aid to help a person understand something. Linkers are used to connect sub programs using different language or tools the linker combines all these bits of code to make them work together. Developing software can also use a number of languages such as: C#, JavaScript, HTML, Python etc.

• Applications

• Steam
• Google Chrome

Multi-Tasking

A Multi-tasking operating System allows several processes at once to be in the RAM at the same.

• Running: The CPU is currently dealing with process and others must wait
• Runnable: The current programs are ready to go and are waiting for the to be completed
• Waiting: These programs are waiting to get into the Queue to become runnable

 

 Operating Systems:

Windows: Windows is the most well known operating system for computers and has be used since 1983

 

MacOS: The second most known Operating software is only available for Apple Computers since

1984 and is run on closed source software

 



Unix: Unix is not known about well and uses a command line interface.







 

 

 Security and Maintenance

 Security and Maintenance is used on all computers using things like backups, Defraggers and Anti-Virus used to protect the used information and protect from unwanted software or software that will slow down your computer. What Defraggers do is when you have some unorganised files and what a disk defragger does is sort them out and stores them. Disk Cleaners are also used to get rid of unused files or software that hasn't been used. Backup software makes a complete copy of selected data onto a second hard drive or external hard drive.