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HIGHER COMPUTER NETWORKING
Lesson 4: Domain Name Service
Description of domain names and name resolution
Domain name servers and domain name resolution
© McLean 2006
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HIGHER COMPUTER NETWORKING
What You Should Know About DNS
Domain names
•
IP addresses are difficult to remember so Domain Names
are used to identify them instead.
•
When we connect to a remote computer using a domain
name such as google.com, a system known as the
Domain Name Service (DNS) translates the domain
name into an IP address
•
This is a technique known as Name Resolution.
© McLean 2006
2
HIGHER COMPUTER NETWORKING
What You Should Know About DNS
Domain name servers
•
A hierarchy of Domain Name Servers store the IP
Addresses of all Domain Names used on the Internet.
•
When a client of a DNS requests a connection to a Domain
Name e.g. google.com the local DNS on a LAN searches
through it’s database and returns the associated IP
Address e.g. 216.239.39.99.
•
If the local DNS does not contain the IP Address for the
requested Domain Name then the request is passed to
another DNS server on the Internet and so on until it is
resolved.
© McLean 2006
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HIGHER COMPUTER NETWORKING
What You Should Know About DNS
Domain name syntax
Domain Names are divided into 2 parts e.g. google.com
The company or organisation Domain Name followed by a suffix or
Domain Name Ending. Some of the most common DN suffixes
are listed below.
DN Ending
.com
.net
.gov
.edu
.org
Meaning
Commercial business, a company
Network or Internet Service Provider
Governmental agency
Educational institution
Non-profit institution
© McLean 2006
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