Computer Networking Complete English Notes | All About Computer Network with steps

Computer Network

A computer network is multiple computers connected together using a telecommunication system for the purpose of communicating and sharing resources. A computer network may be described as the interconnection of two or more computers that may share files and folders, applications, or resources like printers, scanners, webcams etc. Internet is also a type of computer network which connects all the computers of the world having Internet facility on them.
A Simple computer network may be constructed from two computers by adding a network adapter (Network Interface Controller [NIC]) to each computer and then connecting them together with a special cable called a crossover cable. This type of network is useful for transferring information between two computers that are not normally connected to each other by a permanent network connection or for basic home networking applications.

Types of Network

Below is a list of the most common types of computer networks.

Personal Area Network (PAN)

A personal area network (PAN) is a computer network used for communication among computer devices (including telephones and personal digital assistants) close to one person. The reach of a PAN is typically a few meters. PANs can be used for communication among the personal devices themselves or for connecting to a higher level network and the Internet.
Personal area networks may be wired with computer buses such as USB A wireless personal area network (WPAN) can also be made possible with network technologies such as IrDA and Bluetooth.

Local Area Network (LAN)

A network that is limited to a relatively small spatial area such as a room, a single building, is called a local area network. Local area networks are sometimes called a single location network.
For administrative purposes, large LANs are generally divided into smaller logical segments called workgroups. A workgroup is a group of computers that share a common set of resources within a LAN.

Metropolitan Area Network (MAN)

A network that connects two or more Local Area Networks together but does not extended beyond the boundaries of the immediate town, city, or metropolitan area is a metropolitan area network. Multiple routers, switches & hubs are connected to create a MAN.

Wide Area Network (WAN)

A WAN is a data communications network that covers a relatively broad geograpghic area and that often uses transmission facilities provided by common carriers, such as telephone companies.

Advantages and Disadvantages of Network?

Advantage of Network

• Speed : Sharing and transferring files within Networks are vary rapid. Thus saving time, while maintaining the integrity of the file.
• Cost : Individually licensed copies of many popular software programs can be costly. Networkable versions are available at considerable saving. Shared programs, on a network allows for easier upgrading of the program on one single file server, instead of upgradfing individual workstations.
• Security : Sensitive files and programs on a network are password protected (established for specific directories to restrict access to authorized users) or designated as "copy inhibit" so that you do not have to worry about illegal copying of programs.
• Centralize Software Management : Software can be loaded on one computer (the file server) eliminating that need to spend time and energy installing updates and tracking files on independent computers throughout the building.
• Resource Sharing : Resources such as, printer, fax machines and modems can be shared.
• Electronic Mail : E-mail aids in personal and profession communication. Electronic mail on a LAN can enable staff to communicate within the building having not to leave their desk.
• Flexible Access : Access their files from computers throughout the firm.
• Workgroup Computing : Workgroup software (such as Microsoft BckOffice) allows many users to work on a document or project concurrently.

Disadvantages of Network

• Server faults stop application being available
• Network fault can cause loss of data
• Network fault could lead to loss of resources
• User work dependent upon network
• System open to hackers
• Decision tend to become centralized
• Could become inefficient
• Could degrade in performance
• Resources could be located too far from users
• Network management can become difficult

Transmission Media

Transmission media are the components specially wireds which are used for network wiring for the transmission of data within any network. Network media is the actual path over which an electrical signal travels as its moves from one component to another.

Twisted-pair cable

A type of cable that consists of two independently insulated wires twisted around one another. The use of two wires twisted together helps to reduce crosstalk and electromagnetic induction. While twisted-pair is used by older telephone networks and is the least expensive type of LAN cable, most network contain some twisted pair cabling at some point along the network.

Unshielded Twisted Pair (UTP) Cable

Twisted pair cabling comes in two varieties: shielded and unshielded. Unshielded twisted pair (UTP) is the most popular and is generally the best option for school and small business networks.

Coaxial Cable

Coaxial cabling has a single copper conductor at its center. A plastic layer provides insulation between the center conductor and a braided metal shield. The metal shield helps to block any outside interference from fluorescent lights, motors, and other computers.

Fiber Optic Cable

Fiber optic cabling consists of a center glass core surrounded by several layers of protective materials. It transmits light rather than electronic signals eliminating the problem of electrical interference. This makes it ideal for certain environments that contain a large amount of electrical interference. It has also made it the standard for connecting networks between buildings, due to its immunity to the effects of moisture and lighting.
Fiber optic cable has the ability to transmit signals over much longer distances than coaxial and twisted pair. It also has the capability to carry information at vastly greater speeds. This capacity broadens communication possibilities to include services such as video conferencing and interactive services. The cost of fiber optic cabling is comparable to copper cabling; however, it is more difficult to install and modify. 10BaseF refers to the specifications for fiber optic cable carrying Ethernet signals.

Preparing UTP cables for networking

Parallel Cabling

Parallel cabling is made when there is a need of creating a network of more than 2 computer requiring a switch. All the cables are crimped the same way in both of the RJ 45 ends. The color configuration for parallel cabling is given below

RJ45 End 1	RJ45 End 2
Green	Green
Green White	Green White
Orange	Orange
Orange White	Orange White
Blue	Blue
Blue White	Blue White
Brown	Brown
Brown White	Brown White

Cross Cabling

Cross  cabling is made when there is a need of creating a network of only 2 computer without requiring a switch. Only the 4 cables numbered ( 1, 2, 3, 6) are crossed over with each other in the opposite ends of the RJ 45 connectors. The color configuration for cross cabling is given below

RJ45 End 1	RJ45 End 2
Green	Blue White
Green White	Orange
Orange	Green White
Orange White	Orange White
Blue	Blue
Blue White	Green
Brown	Brown
Brown White	Brown White

Note:

• Using the crimping tool, remove the insulator from the UTP cable and separate the colored wires.
• Now straighten the wires using both of your thumbs in any of the two cabling methods.
• Using the crimping tool now cut the wires and insert them in the RJ 45 connector.
• Now crim the wires in the RJ 45 connector. Remember that the insulator must be pressed by the lock of the RJ 45 connector.
• Prepare the cable in another end of the RJ 45 connector as well.
• Use Cable tester to test your cables.

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IP Address

An IP (Internet Protocol) address is a 32-bit unique identification number that is assigned to each computer in a network. It is divided into 4 parts separated by dots and each part is assigned 8 bits (1 byte) and the limitation for each part range from 0-255. Part of an IP address denotes the network address and part of the IP address denotes the node address.
Example: 192.168.0.1
Usually, computers in a network are identified by their names, but they are automatically resolved or translated into its IP address. There are different classed of IP addressed.

Class A IP address

The class A IP address has the format network.node.node.node and the range is 1.0.0.0-255.255.255.255.

Class B IP address

The class B IP address has the format network.network.node.node and the range is 128.0.0.0-191.255.255.255.

Class C IP address

The class C IP address has the format network.network.network.node and the range is 192.0.0.0-223.255.255.255.

Viewing an IP address

Open the command prompt ( Winkey+R type cmd and press Enter )
Type "ipconfig" or "ipconfig /all" and press Enter.
The "ipconfig" command shows the IP address, the subnet mask, and the default gateway. The subnet mask hides the network part and the node part of an IP address and it also shows which class of IP address is being used. The gateway is the computer through which the other computers within a network connect to another network. The "ipconfig /all" command shows all the detailed information about the networked computer.

LAN's Physical Address

Similarly to IP address, each LAN Card has its own physical address that is unique in its and other LAN card in the whole world has the same physical address.
Viewing the LAN's Physical Address
Open the command prompt
Type "getmac" and press Enter. The command returns the physical address of the LAN device.

Assigning the IP address

To assign the IP address, open Run command (winkey + R), type ncpa.cpl and press Enter
In the Local Area Connection Icon, right click on it and select properties.
Select the Internet Protocol (TCP/IP) and click on Properties.
We can assign IP address both automatically and manually. to select an IP address manually, click on "use the following IP address" radio button and give your desired IP address and the default gateway. The "Obtain IP address automatically" option assigns IP address, Subnet mask and default gateway for a computer in a network automatically.

Sharing files and folders

We can share files within a folder that can be accessed by user and computers across a network provided that they have enough permissions.
Steps :

• To share a folder/drive, right click on it and select "Properties" and select "sharing and security or sharing".
• In the sharing tab of the folder properties dialog box, click on "Share this folder / Share" radio button.
• Give the share name and comment for the folder if required
• Click on drop down menu and select user or everyone.
• Click on Permission and apply desired permissions for the users.
• Click Apply and OK.

Viewing Shared files/folders

Steps :

• Click on Start>>Run (Winkey+R). Type the IP address or the hostname of the computer where the shared files are located. The IP address should be followed after two back-slashes. Eg. \\192.168.0.1
• You can also view all the shared files/folders accross a network by simply double clicking on My Network Places Icon on the desktop.
• Click on "view workgroup computers' if you want to view all computers on a network and the shared files/folders on them.

Confidential Sharing

This type of sharing is done when there is a need of sharing file/folder but still want them to hide and deny access from all users. Only the usere who knows the share name of the confidently shared folder can access it. We have to add an extra "$" behind the share name of the folder.
Steps :

• Open the sharing and security dialog box for the folder to which you wish to apply the confidental sharing.
• Add an extra "$" sign after the share name. It will be better if you keep the share name of the folder different from the folder name. Click Apply and Ok.
• To view the confidentially shared folder, give the exact share name with the "$" sign after the IP address.

Eg, \\192.168.0.1\sharename$

Sharing Resources

Various computer resources like Printer, CD-ROM's, Scanners, Webcams can be shared and accessed throughout the network.

Sharing Printers

Steps :

• First make sure that the printer's driver is correctly installed in the computer that has the printer.
• Open the "printer and faxes" properties from the control panel.
• Right click on the printer that you wish to share and select sharing.
• Apply the share printer options in the wizard that appears and click finish.

Adding the shared printer in computers across the network

Steps :

• Open the "Printers and faxes" properties from the control panel.
• Click on "Add Printer" option. In the wizard that appears, click on 'a network printer, or a printer attached to another computer" option and click next.
• You can browse for a printer in the workgroup or provide the exact name and location (name/IP address) of the printer. In some cases, the system may prompt you to enter a password to access the printer. Click Finish when done.
• Now, right click on the just added printer and select properties. Click on "print test page" button to check whether the network printer has beed added successfully or not.

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Managing Users in a Workgroup

Creating Users
Steps :

• Click on Start>>Run (Winkey+R). 
• Type "lusrmgr.msc" and press enter.
• A new window for the local users and groups appear which shows the current users and the group. Click on the users option in the left panel of the window.
• In the right pannel of the user option, right click and select 'new user' or from the menu, select "Action>>New User"
• Now you can create a new user by giving his/her username, full name, description and password. You can also enable/disable options like users needing to change password at next login, user not allowed to change password, password expiration, account disabling etc.
• Click Apply and Ok when done.

Assigning User Privileges

Steps :

• Open the local users and groups window and select the user to which you wish to apply some privileges.
• Right click on the user and select properties.
• Click on "Member of" tab and add your desired privileges to the user.
• Click Apply and OK when done.

Reset / Change / Add User Password

Steps :

• Open the local user and groups window and select the users whose password you wish to reset/change/add.
• Right click on the user ans select "Set Password"
• A window may alert you to change the password by another method. In that case, click on "Proceed". You can also change the password by pressing "Ctrl + Alt + Del" in some cases.
• Provide the new password in the new dialog box that appears and click OK.

Disable a user account

Steps :

• Open the local users and groups window and select the user that you wish to disable the account.
• Right click on it and select properties.
• In the general tab, click to check "account is disabled" checkbox to disable the user account.
• Click OK to finish.

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Using the tracert (Traceroute) command

The tracert command finds out at how many hops distance the next computer is located. This command is appliedto either the hostname or the IP address. It returns the hostname if we provide the IP addresses and vice versa, only if it is connected. It also counts the hops (maximum of 30) distance and gives a statistical result with total time taken in milliseconds.
Syntax: tracert IP address or tracert hostname
Eg: tracert 192.168.0.1

Turning off the firewall

Steps :

• Click on Start>>Run (Winkey + R)
• In the run command, type firewall.cpl and press Enter. Or, got to control panel and double click on "Windows Firewall"
• In the windows firewall dialog box, click on Off to disable the windows firewall, but this is not always recommended.
• Click OK to finish.

Sending Messages

We can send messages to the computer to the computers throughout the network using the net send command. The message can be unicasted or broadcasted if the messenger services in all computers is up and running.
Starting the messenger services
Steps :

• Open the Windows Services Console. (Type services.msc in the Run Command and press enter)
• Double Click on The Messenger services from the list of services in the right panel of the window.
• Set the Messenger services to automatic and click start (if necessary). This will start the messenger services in the computer. Click on Apply and OK and close the Services Window.

Sending Messages using the net send command

Steps :

• Open the command propt window
• Type the following command to send a "Hello" message to 192.168.0.1 and press Enter.
• net send 192.168.0.1 "Hello"
• Type the following command to send the same "Hello" message to all computers throughout the network.
• net send  * "Hello"

Mapping a network drive

We can map a shared folder of another computer as a drive in our computer as a drive if we need to access the same shared folder quite frequently.
Steps :

• First make sure that the shared folder has enough permissions for your computer to map it as a network drive.
• Now in the computer where you wish to map a network drive, right click on my computer and select "Map Network Drive"
• In the wizard that appears, select your network drive letter and either browse your desired shared folder or directly input the location of the shared folder. Make sure that the 'reconnect at login" option is checked.
• Give username/password if required and click on Finish.
• Double click on my computer to view the network drive you just mapped.

Disconnecting a Mapped Network Drive

Steps :

• Right click on My Computer and select "Disconnect Network Drive" in the computer from which you wish to disconnect the mapped network drive.
• Select the network drive and click OK.

Cyber Networking

An Internet Cyber usually consists of an internet server and many other client computers. The internet server receives the internet connection from any ISP (Internet Service Provider) and share the connection among the clients. If the Internet Service is accessing the cable or dialup internet, following factors should be taken into considerations.
IP address of the local area network should always be assigned as 192.168.0.1
IP address of other client computer can be configured automatically or manually. If automatic IP addressing is used, then we do not have to configure anything. If manual IP address is used, then the gateway should be assigned as 192.168.0.1 and the preferred and alternate DNS servers (if the ISP manages them) should also be assigned in each client computers.
Either the internet connection or the local area network should be shared depending on the type of internet service used.
Steps :

• Right click on the Local Area connection (in network connections) and select properties.
• In the advance tab, select "allow other network users to connect through this computer's internet connection" option and click OK.

Furthermore, proxy servers and port numbers should also be given (if required) in the internet options of client computer if the IPS used them. A proxy server is a type of intermediate server that receives requests from client computers and again transfers those request to another server. A port is a special number present in the header of a data packet. Ports are typically used to map data to a particular process running on a computer. HTTP uses port 80, FTP uses 21 and telnet uses 23.
Steps :

• Open the internet explorer, and click on Tools>>Internet Options or, from run command, type inetcpl.cpl and Press Enter.
• In the internet properties dialog box, click on Connections tab and click on LAN settings button.
• In the LAN settings dialog box that appears, click on 'Use a Proxy Server for your LAN" option and provide the correct Proxy Server's IP and the port number. Do not select the 'Bypass proxy server for local addressed" option.
• Click OK.

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What is Telnet? Definition of Telnet

Telnet is used to access and control a computer remotely within a network. Usually, telnet is done via the command line, but nowadays GUI based telnet program are also available. Before using the telnet program on a network, both of the connecting computers should have the telnet services up and running.
Starting the telnet services
Steps :

• Click on Start>>Run (Winkey + R). Type services.msc and press Enter to open Windows Services Console.
• In the right panel, double click on telnet services.
• Click on start button to start the telnet services. If the services is disabled, select either automatic or manual from the drop down menu and start the telnet service.
• Close the Windows Services Console.

Using the telnet command

Steps :

• First make sure the telnet services is running on both computers
• Open the command prompt type the command as per the syntax given below
• Syntax: telnet IP Address and press enter
• The connection may prompt you to provide a username and password. After that you can access and control the connected computer.

Remote Desktop

In windows Operating system, we can use the remote desktop feature to access and manage a remote computer within a network. To connect to a remote computer, the remote desktop feature should be selected in the remote computer.
Enabling Remote Desktop
In the remote computer, right click on My Computer and select Properties.
In the system properties, select the remote tab.
Select "Turn on remote assistance and allow invitions to be sent from this computer" and "Enable Remote desktop on this computer" option and click OK.

Accessing the remote computer

Click on Start>> Programs>> Accessories>> Communications>> Remote Desktop Connection or Type "mstsc.exe" in run command box and press enter.
In the dialog box that appears, input the IP address and Click on connect.
You may need to provide a privileged username and password to access the computer. After that you will be able to access the control a remote computer.
Click on Close button on the top bar of the desktop to disconnect.

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Viewing Workgroup

Open the system properties (Right click on My Computer and select Properties, or press Winkey + Pause Break)
Select "Computer Name" tab from the System Properties.
The name beside the workgroup is the workgroup name of that computer.

Changing Workgroup

Open the system properties (Right click on My Computer and select Properties, or press Winkey + Pause Break)
Select "Computer Name" tab from the System Properties.
Click on change button. To change the workgroup name, we should login with administrator's account.
In the "member of" selection select the "workgroup" radio button and type the workgroup name and click OK.
Again click Apply and OK and Restart your Computer.

Useful Commands (Command prompt)

arp (address resolution protocpl) This command returns all the connected computers in a network along with their physical address
Syntax: arp -a Note : type arp /? for more information

Cleanmgr Automatically clears temporary files and recycle bin
Syntax: cleanmgr and select the drive you wish to clean

Shutdown
This command is used to shutdown/restart a computer
shutdown -s : immediate shutdown with timeout
shutdown -r : shutdown and restart
shutdown -a : abort shutdown/restart
shutdown -p : shutdown with no timeout
shutdown -h : hibernate the computer

Hostname
Returns the hostname of the computer

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