What is domain name

Domain names are used to identify one or more IP addresses.  For example, the domain name microsoft.com represents about a dozen IP addresses.  Domain names are used in URLs to identify particular Web pages.  For example, in the URLhttp://wwwpcwebopedia.com/index.html, the domain name is pcwebopedia.com.

Every domain name has a suffix that indicates which top level domain (TLD) it belongs to. There are only a limited number of such domains. For example:

gov - Government agencies

edu - Educational institutions

org - Organizations (nonprofit)

mil - Military

com - commercial business

net - Network organizations

ca - Canada

th - Thailand

Because the Internet is based on IP addresses, not domain names, every Web server requires a Domain Name System (DNS) server to translate domain names into IP addresses.

What is Internet Addressing System

Internet address is made up of a code or series or letters, numbers and /or symbols by which  the Internet identifies you or a location where information is stored.  Through the use of this addresses, people can send you e-mail look at your Web site and send or receive files and documents.

what is Packet Switching

In this scheme, no dedicated path is reserved between source and destination.  The data to be sent is 'wrapped up' in a packet and launched into the network.  Circuit is switching is extensively  used in the public telephone networks, with each conversation between users traveling over a dedicated path from one telephone through the central switch to the other party.

Hardware requirement of LAN

There are mainly 4 hardware devices which are required to establish linkage between geographically separated computers.  These are:

• Bridges
• Routers
• Gateways
• x.25 Standard Interface

Bridge-  These are used to connect two LANs that use the indentical protocols over a wide area.  The bridge acts as an address filters which picks up packets from one LAN that are intended for a destination on another LAN and passes these packets on the network. The amount of processing required at the bridge is minimal because all the devices use the same protocols.  In case the distance between two LANs is very large then the user is required to employ two identical bridges at either end of the communication link.

Routers-  It is special type of device that can be used to connect networks that may not be similar.  Such type of device provide connectivity between two LANs and two WANs over large geographical distances.  These device operate at the Network Layer of the OSI model.  These devices participate in a routing protocol to access the network topology, and on the basis  of this information routers compute the best route from a sender to the receiver.

Gateways-  These are used dsto connect two dissimilar LANs.  The terms Gateways and Routers are used interchangeably, though there is discriminating difference between the two.  A router  operates at the networklayer whereas a gateway operates on the application layer of the OSI model.  

x.25 Standard Interface-  X.25 is a protocol  for interfacing to a Public Packet Switched Network.  It is not a protocol used for immplementing a network.  Two systems that support X.25 can't necessarily be connected back-to-back.  They can only be connected through a DCE in a Public Packet Switched Inernational Telegraph and Telephone Consultative committee (ITTCC) developed X.25 as the standard interface between the Data Terminal Equipment (DTE)and Data Circuit Terminating Equipment (DCTE).  This recommendation has been widely accepted as the industry standard for public packet switched networks.

Server and Workstations

One of the major benefits of implementation of LAN is sharing expensive resources such as storage devices, printers, etc. This is achieved through providing servers on  the LAN.  It is dedicated computer that controls one or more resources.  This contains both hardware and software interface  for LAN.  Three major categories of services used in LANs are.

• File Server
• Printer Server
• Modem Server

In networking file server is used to share storage for files.  Besides providing storage space for files in a LAN environment, it is used for taking periodical backup, and also to provide gateway to other servers with and between LANs.  Similarly printer server is used to handle printing works of all workstation connected in the network or simply to use a telephone.  A modem server is used to share this expensive resource by all connected workstations in a network ring.

 

Hardware for LAN

The following are the major hardware components/devices for establishing LAN:

• Transmission Channel
• Network Interface Unit or NIU
• Servers
• Workstations

Asynchronous Transfer Mode (ATM)

It is new in term of modes available for networking.  It can carry both voice and data. It is also based on packet data technology. On an ATM network, every station transmits continuously.  ATM is a circuit based network, in that a virtual circuit is set up between two devices to communicate over the network.