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DNS
is a host name to IP address translation service
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DNS
is a distributed database implemented in a hierarchy of name servers, an application
level protocol for message exchange between clients and servers
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A
lookup mechanism for translating objects into other objects
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A
globally distributed, loosely coherent, scalable, reliable, dynamic database
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Comprised
of three components
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A “name
space”
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Servers
making that name space available
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Resolvers
(clients) which query the servers about the name space
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It
is easier to remember a host name than it is to remember an IP address.
Ø
A
name has more meaning to a user than a 4 byte number.
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Applications
such as FTP, HTTP, email, etc., all require the user to input a destination.
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The
user generally enters a host name.
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The
application takes the host name supplied by the user and forwards it to DNS for
translation to
an IP address.
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DNS
works by exchanging messages between client and server machines.
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A
client application will pass the destination host name to the DNS process to get
the IP address.
Ø The
application then sits and waits for the response to return.
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