Computer Networks

Computer Networks

Definition

Computer networking is the scientific and engineering discipline concerned with communication between computer systems.

The word network can be used to describe a very large and complicated set of equipment. In its most accurate and simplest definition, a network refers to the cables and electronic components that amplify the signals going through the cables. The amplifying equipment is necessary to ensure accurate communication and make the signal stronger if it needs to go long distances.
Broader Definition
When many people talk about a network, they are talking about a network using a very broad concept. For instance, if someone cannot get to their email, they may say “the network is down”. Likewise, they may say this if they cannot surf the internet or get to their files. They may not stop to think that in each specific instance there is a single piece of equipment that may provide the capability which they are trying to use.
Most people who work on a corporate or organizational network think about the network in component parts. The three main parts are:
• The cabling and amplifiers mentioned in the first paragraph.
• The workstations which most members of the organization use to access resources.
Higher powered computers called servers – These are the machines that provide what network administrators call services. Services include the functions that most people try to use such as email, reading and writing files, printing, and getting to the internet. Whenever a user is trying to do something on the network, there is a service or machine providing the capability to do so. This even includes times when someone is trying to get to network resources from their home.
Services
Services include:
• Email service
File service – Allows users to use and share file space on a computer with a lot of file space.
Print service – Allows printing to printers connected on the network.
Web surfing – Allowing someone to open web pages and see web sites on the internet.
Filtering out undesired sites on the internet.
• Allowing someone to access the network from the outside (from home).
• Updating virus definitions on workstations
• Allowing someone to log onto the network.
• Even giving a workstation an address on the network is a service. If your computer does not have an address, it cannot access the internet or any other resource on the network.
A Typical Network
A typical corporate or organizational network is shown below:
The private network is, of course, the most secure part of the network. There are several servers on this network including:
• A login server (called a domain controller) which controls everyone permissions and access to the network resources such as files. Without this server, they cannot login to the network.
• An address server (called a DHCP server) which provides addresses to computers on the network so they can communicate as discussed earlier.
• A file server which provides common files and a private folder for users
• A remote access server which allows users to connect to the network by telephone from the outside.

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