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NETWORK BASICS

Network A system of interconnected computers and computerized peripherals such as printers is called computer network. This interconnection among computers facilitates information sharing among them. Computers may connect to each other by either wired or wireless media. A computer network consists of a collection of computers, printers and other equipment that is connected together so that they can communicate with each other.  


Network application
A Network application is any application running on one host and provides a communication to another application running on a different host, the application may use an existing application layer protocols such as: HTTP(e.g. the Browser and web server), SMTP(e.g. the email-client). And may be the application does not use any existing protocols and depends on the socket programming to communicate to another application. So the web application is a type of the network applications. 
There are lots of advantages from build up a network, but the th…

NETWORK IMPLEMENTATION & OSI MODEL

NETWORK IMPLEMENTATION  & OSI MODELShared resources, also known as network resources, refer to computer data, information, or hardware devices that can be easily accessed from a remote computer through a local area network (LAN) or enterprise intranet. Successful shared resource access allows users to operate as if the shared resource were on their own computer. The most frequently used shared network environment objects are files, data, and multimedia and hardware resources like printers, fax machines and scanners. 
Shared LAN points are used by a variety of system resources, such as hard drives, printers, scanners and network cards.  

File and printer sharing occur via two network communication mechanisms: peer-to-peer (P2P) sharing and the client-server network model. 

Sharing network resources requires abiding by certain constraints, as follows: 

  • Security: Organizations present ongoing opportunities for unauthorized shared resources. Security mechanisms should be implemented to provide efficient parameters. 
  • Compatibility: Various client-server operating systems may be installed, but the client must have a compatible OS or application to access shared resources. Otherwise, the client may encounter issues that create communication delays and requires troubleshooting.  
  • Mapping: Any shared OS hardware drive, file or resource may be accessed via mapping, which requires a shared destination address and naming conventions. 
  • File Transfer Protocol (FTP) and File Sharing: FTP is not affected by shared resources because the Internet is FTP’s backbone. File sharing is an LAN concept. 
File sharing is the public or private sharing of computer data or space in a network with various levels of access privilege. While files can easily be shared outside a network (for example, simply by handing or mailing someone your file on a diskette), the term file sharing almost always means sharing files in a network, even if in a small local area network. File sharing allows a number of people to use the same file or file by some combination of being able to read or view it, write to or modify it, copy it, or print it. Typically, a file sharing system has one or more administrators. Users may all have the same or may have different levels of access privilege. File sharing can also mean having an allocated amount of personal file storage in a common file system. 



Determine if your computer belongs to a home group, work-group, or domain. To begin the process of sharing folders and to follow the proper steps, you must find out which network you belong to.  
  • Find out if your computer is part of a home group by clicking the "Start" button or Windows logo in the bottom-left corner of your screen. Click on "Control Panel." In the  
  • Search box in the upper-right corner, type in "Network" and click on the "Network and Sharing Center" link when the search results appear. Check the status next to the "Home group" field. If the status is "Joined," then your computer belongs to a home group. 
  • Find out if your computer is part of a work-group or domain by clicking the "Start" button or Windows logo in the bottom-left corner of your screen. Right-click on "Computer" and select "Properties." Under the section for "Computer name, domain, and work-group settings," you will see either the word "Work-group" or "Domain" followed by its name. 

Add a shared folder to a home group. Locate the folder you want to share and right-click on it. Point to "Share with" and choose your desired sharing option from Home group (Read), Home group (Read/Write), or Specific People.  
  • Select "Home group (Read)" to share the folder with every computer in the home group in a read-only format. Nobody else will have the ability to modify or delete the folder and its contents. 
  • Select "Home group (Read/Write)" to give every computer in the home group permission to read, modify and delete the folder and its contents. 
  • Select "Specific People" to open the File Sharing Wizard, which will allow you to designate the users you want to share files with. When the wizard opens, type in a user's name or click on the arrow to display a drop-down menu that displays all names in the home group. Designate the desired permission level by choosing from "Read" or "Read/Write." "Read" will allow users to read the files but will not allow them to modify or delete them. "Read/Write" will allow users to read, modify, and delete the files. Click on the "Share" button at the bottom of the wizard to finish. 

Add a shared folder to a work-group or domain. Locate the folder you want to share and right-click on it. Point to "Share with" and then click "Specific People" to open the File Sharing Wizard.  
  • If you have a work-group computer, click on the arrow next to the text box and select the correct name from the list. Click "Add" to add a shared folder to that work-group. 
  • If your computer is part of a domain, click on the arrow next to the text box and select "Find People." Type the correct name into the dialog box next to "Select Users or Groups" and click "Check Names." Click on "OK" to proceed. 
  • Designate the desired permission level by choosing from "Read" or "Read/Write." Under the "Permission Level" column, designate the desired option. "Read" will allow users to read the files but will not allow them to modify or delete them. "Read/Write" will allow users to read, modify, and delete the files. Click on the "Share" button at the bottom of the wizard to proceed. Depending on how the network is set up, you may be prompted to enter an administrator password or provide confirmation.
  • Notify the users you've shared with of the new shared items. Click on "E-mail" to send users a link to the shared folder if you have an e-mail program installed or click "Copy" to copy the displayed link to the Windows Clipboard and paste it into an e-mail, instant message, or other program. Click "Done" to finish the process of adding a shared folder to the domain. 

Check to see if a folder is shared. To view the sharing details of a folder or file, open Windows Explorer by clicking on the Start button or Windows logo on the bottom-left corner of your screen. Click on your user name to display your folders and files. Click on any folder or file to display sharing details in the bottom window pane. 


Remove shared folders. If you want to stop sharing a folder, right-click the folder you want to stop sharing, click on "Share with," then click "Nobody." 


Windows Server 2008 is a server operating system it is not surprising that a primary function of this operating system is to serve files to users on other systems on a network. 
Standard and Public File Sharing  
Windows Server 2008 supports two types of file sharing, referred to as public file sharing and standard file sharing.  
In the case of public file sharing any files to be shared must be copied to the server's Public folder located at %System-drive%\Users\Public. Once placed in this folder the files are accessible to any users logged locally onto the machine and, if enabled, to any network users. Public sharing provides some control over access to the files. For example, when the server belongs to a work-group the public folder can be password protected. In addition, network access to files within the public folder can be restricted to reading and executing only or given permission to read, write, create and delete files. Standard file sharing, which is only permitted on NTFS volumes, allows individual folders files and volumes to be shared to specific users. This provides far greater levels of security over network access through a combination of NTFS file and folder permissions and share permissions, and avoids the necessity to move files from their existing location in order to share them.  


From the Network and Sharing Center, accessed by selecting Start -> Network and clicking on the Network and Sharing Center button in the toolbar. 
To enable public file sharing, click on the down arrow next to the Public folder sharing in the section entitled Sharing and discovery. This will provide the following list of public folder sharing options:  
  • Turn on sharing so anyone with network access can open files - Allows network users to open, but not delete, modify or create files in the server's public folder.  
  • Turn on sharing so anyone with network access can open, change and create files - Allows network users to open, modify, delete and create files in the public folder.  
  • Turn off sharing (people logged on to this computer can still access this folder) - Allow public folder access only to those users locally logged on to the server. Network users are denied access.  
Similarly, standard file sharing can be configured by click the down arrow next to File sharing. When unfolded, this panel provides the option to either enable or disable standard file sharing on this server. When enabled, a dialog will appear providing the option to make the shared folders available only to the private network on which the system resides, or to make sharing available to public networks. The choice here depends on the requirements of the organization but for security purposes it is typically best to limit sharing to the private network unless external access is required.  

The Network and Sharing Center also allows password access to shared folders to be configured. When the arrow next to Password protected sharing is selected the options to enable or disable password protection sharing are provided. When enabled on work-group servers, only users with user accounts and passwords on the server will be able to access shared files and folders. 


Shared folders can be configured using Windows Explorer, simply by navigating to the folder to be shared, right clicking on the folder and selecting Properties from the menu. In the properties dialog, click on the Sharing tab to display and modify the current shared folder settings. 


Within the sharing property panel, click on the Share Button to access the File Sharing dialog. Within this dialog, the users who may access this shared folder are specified. If file sharing has been restricted to users with local accounts and passwords, a list of users can be obtained by clicking on the down arrow. In this situation, select and add users, or select everyone if access is to be made available to all users with local accounts: 
 

Once these settings are complete, click on the Share button to initiate the file sharing process. Once this initial phase of the share setup is complete a dialog will appear announcing this fact, listing the full Universal Naming Convention (UNC) path to the shared folder and providing the option to email users to notify them of this fact. 


To configure these settings, click on the Advanced Sharing button to display the following dialog.  


Once this has been selected the Share name field and associated button will activate enabling a share name to be entered. By default the name of the folder being shared will be displayed, although this may be changed to another name if desired. If the number of concurrent users accessing a shared folder is of concern, modify the number of simultaneous users accordingly. Enter optional comments about the share before clicking on Caching to configure the off-line file settings. This will invoke the Offline Settings dialog where a number of options are available including allowing each user to specify which files they would like to be able to access off-line, only having files that users actually access available off-line and disabling offline sharing all together. 


After starting Computer Management on the local system, right click on Computer Management in the left panel tree and select Connect to another computer. In the resulting dialog box either enter the name of the remote computer or click on Browse and then Advanced. to search the network or domain for the remote system. Once a connection has been established to the remote server the Computer Management interface will refresh and the Computer Management link in the tree will also display the name of the selected remote server. Once Computer Management is configured to administer a remote server, the next step is to begin the folder sharing process. Begin by unfolding the System Tools, then Shared Folders branches of the tree in the left panel. Select Shares to obtain a list of current shares configured on the remote system.  


The creation of a new shared folder on the remote server (although as previously mentioned this can also be used on local computers) involves the use of something called the Create a Shared Folder Wizard, which, as the name suggests provides a user friendly way of configuring shared folders. To invoke this wizard, simply right click on New Share. Then click on Next on the wizard's welcome screen. In the resulting Folder Path screen, either type in the path of the folder to be shared, or browse the file systems to locate it. With the required folder path selected click on Next to configure the name and description settings. On this screen, specify the share name by which the folder will be accessed from remote computers together with an optional description of the shared folder. Next, configure the off-line file settings for the folder contents by clicking on Change. 


Once these settings are configured, click on Next once again to configure the share permissions for the selected folder. Either select one of the pre-configured options or select Customize permissions and click on Custom to configure share permissions on a per user basis. Finally, click on finish to complete the sharing process. If the configuration is successful a summary screen. 


Internet connection sharing is a method for connecting multiple computers in a LAN to the Internet through a single connection and a single IP address. ICS typically uses NAT technologies to achieve this and works with most connection technologies, including DSL, cable, ISDN, dial-up and satellite. The device with the modem or broadband interface that establishes the connection to the Internet is called the ICS host, or gateway while the other devices that connect to the Internet via the network and the ICS host are called ICS clients. If the ICS host fails, then all of the ICS clients lose their Internet connection. Sharing an Internet connection can be achieved through either software or hardware solutions. All versions of Windows from Windows 98 and on have ICS software included in the operating system. However, there are also products such as Win-gate and Win Proxy, which are third-party shareware alternatives that will turn a computer into a gateway or proxy server. Hardware solutions involve a NAT-based hardware router that is connected directly to the Internet connection adapter, and each ICS client is then connected to the router.  



Choose Start Control Panel→Network and Internet. Click the Network and Sharing Center link. The Network and Sharing Center opens.  


In the resulting Network and Sharing Center window, click the Manage Wireless Network's link. The window that appears lets you "Manage Wireless Networks That Use (Wireless Network Connect)." 


Click a connection and then click the Adapter Properties link. The Connection Properties dialog box appears. 


Click the Sharing tab. This tab doesn't give you a whole lot of options


Select the Allow Other Network Users to Connect through This Computer’s Internet Connection check box. You might also be able to select the Allow Other Network Users to Control or Disable the Shared Internet Connection check box (Optional). This setting lets other people on your network control the shared Internet connection by enabling or disabling it. 


Click OK and then close the Manage Wireless Networks window to save the shared connection settings. Before they can start using your shared connection, users on your network need to configure their TCP/IP settings so that they get an IP connection automatically. 

Sharing Internet Connection via Proxy Server  

Introduction on Sharing Internet Connection and Proxy Server Software - Cc-proxy  
Most small businesses have more than one PC but with only one Internet connection. How to make all of the computers connected to the Internet? Many households are facing same problem too. Proxy server can help you sharing Internet connection with your colleagues and home members even if you have only one modem. 
There are many proxy server software’s for you to build your own proxy server for sharing an Internet connection. CCProxy is such a proxy server software, it's easy-to-use, powerful and efficient. With CCProxy you can implement Internet connection share solution in minutes. As a Windows proxy server software, CCProxy can be installed on various Windows OS versions, it's compatible with Windows XP, Windows 7, Windows Server 2003, and Windows Server 2008 etc., both 32 bit and 64 bit. CCProxy is mostly used for Windows Internet sharing. The point is CCProxy server is also available for clients with other OS such as Linux, Apple, and Mobile OS etc.  
For personal users and family users, CCProxy is a free proxy server software, the 3 user free version works the same as registered version. The only limitation is it can support only 3 clients, but for most uncommercial user it's enough.  
Proxy Server Installation and Configuration for Sharing Internet Connection  
Step 1 Proxy Server Setup and Initialization  
  • Suppose the proxy server address is 192.168.0.1.  
  • Download CCProxy from the download center, run ccproxysetup.exe and keep clicking the "Next" button to finish the installation.  
  • Launch CCProxy on the server for sharing Internet connection  
 If you get problem in launch CCProxy, please refer to "CCProxy Start Problem".
  
Step 2 Create Accounts for Clients on CCProxy Server  

After set up proxy server with CCProxy, you can create accounts and specify the authentication type for your own proxy server in the "Account Manager" dialog box of CCProxy as bellow. 

There are 2 authentication types for you to select:  

Anonymous - please select "Permit All" for "Permit Category"  

Authentication required - please select "Permit only" for "Permit Category" and then select proper "Auto Type" as you wish.  CCProxy supports several authentication types such as "IP Address", "MAC Address", "User/Password" and some combined auto types as you can see in the "Account Manager" dialog box. For sharing Internet connection, we recommend "IP Address" authentication type.  

Step 3 - Make proxy server settings for IE on client  
  • Go to client computer and open IE window.  
  • Open "Tools" menu, select "Internet Options" and open the "Internet Options" dialog box.  
  • Select "Connections" tab, click "LAN Settings" button and open the "Local Area Network (LAN) Settings" dialog box.  
  • Check "Use a proxy server for your LAN", Fill "192.168.0.1" in "Address" and "808" in "Port"  
  • Click "OK" button in "Local Area Network (LAN) Settings" and "Internet Options" dialog boxes.  
  • Now you can browser Internet web sites in IE at the client. 

Install computer as per the requirement. 


Make sure that OS should installed in all computer. 


Take a new connection from nearest ISP (Internet service provider) 


Buy & install a switch. Make sure that the no of port available in the network switch should match with no of computer installed for LAN connection. 


Plug in the LAN cable provided by the ISP into any port of the switch.  


Connect all computer with the switch through LAN cable (Cat 5, Cat 5e, Cat 6 etc.).Make sure if Windows Xp is installed in computer then Network driver need to be installed, else if windows 7, windows 8 or windows 10 is installed network driver is pre-installed. 


Open the browser & & check your internet connectivity. Make sure that LAN cable should be connected in both end (switch, computer). 


By using Command prompt you can also check the internet connectivity. Press windows key & “R” button together & type ping www.google.com & press enter. 


You will get the screen mentioned below. 


OSI (Open Systems Interconnection) is reference model for how applications can communicate over a network. A reference model is a conceptual framework for understanding relationships. The purpose of the OSI reference model is to guide vendors and developers so the digital communication products and software programs they create will interoperate, and to facilitate clear comparisons among communications tools. Most vendors involved in telecommunications make an attempt to describe their products and services in relation to the OSI model. And although useful for guiding discussion and evaluation, OSI is rarely actually implemented, as few network products or standard tools keep all related functions together in well-defined layers as related to the model. The TCP/IP protocols, which define the Internet, do not map cleanly to the OSI model. 
The main concept of OSI is that the process of communication between two endpoints in a telecommunication network can be divided into seven distinct groups of related functions, or layers. Each communicating user or program is at a computer that can provide those seven layers of function. So in a given message between users, there will be a flow of data down through the layers in the source computer, across the network and then up through the layers in the receiving computer. The seven layers of function are provided by a combination of applications, operating systems, network card device drivers and networking hardware that enable a system to put a signal on a network cable or out over Wi-Fi or other wireless protocol). The Open system Interconnection (OSI) model defines a networking framework to implement protocols in seven layers. Control is passed from one layer to the next, starting at the application layer in one station, and proceeding to the bottom layer, over the channel to the next station and back up the hierarchy. 
There is really nothing to the OSI model. In fact, it's not even tangible. The OSI model doesn't perform any functions in the networking process. It is a conceptual framework so we can better understand complex interactions that are happening. 

This layered model is a conceptualized view of how one system should communicate with the other, using various protocols defined in each layer. 


This layer conveys the bit stream - electrical impulse, light or radio signal — through the network at the electrical and mechanical level. It provides the hardware means of sending and receiving data on a carrier, including defining cables, cards and physical aspects. Fast Ethernet, RS232, and ATM are protocols with physical layer components. 
  • Layer 1 Physical examples include Ethernet, FDDI, B8ZS, V.35, V.24, and RJ45. 

At this layer, data packets are encoded and decoded into bits. It furnishes transmission protocol knowledge and management and handles errors in the physical layer, flow control and frame synchronization. The data link layer is divided into two sub layers: The Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. The MAC sub layer controls how a computer on the network gains access to the data and permission to transmit it. The LLC layer controls frame synchronization, flow control and error checking. 
  • Layer 2 Data Link examples include PPP, FDDI, ATM, IEEE 802.5/ 802.2, IEEE 802.3/802.2, HDLC, and Frame Relay.  

This layer provides switching and routing technologies, creating logical paths, known as virtual circuits, for transmitting data from node to node. Routing and forwarding are functions of this layer, as well as addressing, inter-networking, error handling, congestion control and packet sequencing. 
  • Layer 3 Network examples include AppleTalk DDP, IP, and IPX. 
Transport (Layer 4) 
This layer provides transparent transfer of data between end systems, or hosts, and is responsible for end-to-end error recovery and flow control. It ensures complete data transfer. 
  • Layer 4 Transport examples include SPX, TCP, and UDP. 

This layer establishes, manages and terminates connections between applications. The session layer sets up, coordinates, and terminates conversations, exchanges, and dialogues between the applications at each end. It deals with session and connection coordination. 
  • Layer 5 Session examples include NFS, Net-BIOS names, RPC, SQL. 

This layer provides independence from differences in data representation (e.g., encryption) by translating from application to network format, and vice versa. The presentation layer works to transform data into the form that the application layer can accept. This layer formats and encrypts data to be sent across a network, providing freedom from compatibility problems. It is sometimes called the syntax layer. 

Layer 6 Presentation examples include encryption, ASCII, EBCDIC, TIFF, GIF, PICT, JPEG, MPEG, and MIDI. 


This layer supports application and end-user processes. Communication partners are identified, quality of service is identified, user authentication and privacy are considered, and any constraints on data syntax are identified. Everything at this layer is application-specific. This layer provides application services for file transfers, e-mail, and other network software services. Telnet and FTP are applications that exist entirely in the application level. Tiered application architectures are part of this layer. 
  • Layer 7 Application examples include WWW browsers, NFS, SNMP, Telnet, HTTP, FTP 
  • Share a file over a network  
  • Give permission to various shared file or folders.  
  • Share a LAN without proxy setting.  
  • Share LAN using proxy setting.  


a) LAN  
b) WAN 
c) MAN  
d) none of the mentioned 


a) 2  
b) 4  
c) 7  
d) 8  


a) Packet Filtering  
b) Internet-work communication  
c) Path selection  
d) All of the above  


a) Network  
b) Presentation  
c) Data link  
d) Transport  


a) Application  
b) Physical  
c) Transport  
d) Data link  

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