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Presented by:- Vishal Mittal15-CSE-2835

DOMAIN NAME SYSTEM

OverviewIntroduction to the DNSDNS ComponentsDNS Structure and HierarchyThe DNS in Context

What is DNS?Domain Name System (Server) An Internetservice that translatesDomain Namesinto IP addresses. Because domain names are alphabetic & they are easier to remember.

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1. What is the IP address of udel.edu ?DNS 1. What is the host name of 128.175.13.74It is 128.175.13.92It is strauss.udel.edu

DNS Components

5There are 3 components:Name Space: Specifications for a structured name space and data associated with the namesResolvers:Client programs that extract information from Name Servers.Name Servers:Server programs which hold information about the structure and the names.

Name Space

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ResolversA Resolver maps a name to an address and vice versa.7

Query

Response

ResolverName Server

Recursive Resolution8

clientrecursive requestWhat is the IP address of www.google.com?

udel server

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edu server

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root server

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com server4

googleserver5recursive responseThe IP address of www.google.com is 216.239.37.99.

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Name servers store information about the name space in units called zonesUsually, more than one name server are authoritative for the same zoneThis ensures redundancy and spreads the loadAlso, a single name server may be authoritative for many zonesName Servers

Block Diagram10

User ProgramForeign Name ServerCacheResolver

QueryQueryReference

ResponseAdditionResponse

Acknowledgements www.cis.udel.edu Wikipediawww.webopedia.com

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Questions