Q. Illustrate Domain Name System?
Domain name is a name which is given to a network for ease of reference. Domain refers to a group of computers which are known by a single common name. Somebody has to transfer these domain names in IP addresses. It is decided on physical location of the web server as well as where domain name is registered. Some generic domain names are:
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Domain name
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Description
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Com
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Commercial organization
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Edu
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Educational organization
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Gov
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Government organization
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Mil
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Military group
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Org
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Non-profit organization
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Hence, humans use domain names when referring to computers on the Internet, while computers work only with IP addresses, which are numeric. DNS was developed as a distributed database. Database contains the mappings between domain names and IP addresses scattered across different computers. This DNS was consulted whenever any message is to be sent to any computer on Internet. DNS is based on the creation of hierarchical domain based naming architecture, which is implemented as a distributed database. It's used for mapping host names & email addresses to IP addresses. Every organization operates a domain name server which contains list of all computers in that organization along with their IP addresses. When an application program needs to translate a computer's name into computer's IP address, application becomes a client of the DNS. It contacts a domain name server and sends the server an alphabetic computer name then server returns the correct IP address. Domain name system works like a directory.
A given server doesn't store the names and addresses of all possible computers in Internet. Every server stores the name of computers at only one enterprise or company.